Galilei, Galileo, The systems of the world, 1661

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Author: Galilei, Galileo
Title: The systems of the world
Date: 1661

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1
THE
SYSTEME
OF THE
WORLD:
IN FOUR
DIALOGUES.
Wherein the Two
GRAND SYSTEMES
Of PTOLOMY and COPERNICUS
are largely diſcourſed of:
And the REASONS, both Phyloſophical and Phyſical,
as well on the one ſide as the other, impartially
and indefinitely propounded:
By GALILEUS GALILEUS LINCEUS,
A Gentleman of FLORENCE: Extraordinary Profeſſor of
the Mathematicks in the UNIVERSITY of PISA; and
Chief Mathematician to the GRAND DUKE of TVSCANY.
Ingliſhed from the Original Italián Copy, by THOMAS SALUSBURY.
ALCINOUS,
Δεῑ δ̓ ἐλευγέριον εἰ̄ναι τῃ̄ γνωμῃ̄ ρ̀ν μέλλοντα φιλοσοφεῑν.
SENECA,
Inter nullos magis quam inter PHILOSOPHOS eſſe debet aqua LIBERTAS.
LONDON,
Printed by WILLIAM LEYBOURNE. MDCLXI.
1
[Empty page]
1
To the moſt Serene Grand DUKE
OF
TUSCANY.
Though the difference between Men and other
living Creatures be very great, yet happly he that
ſhould ſay that he could ſhew little leſs between
Man and Man would not ſpeak more than he
might prove. What proportion doth one bear to
athouſand? and yet it is a common Proverb, One Man is
worth athouſand, when as a thouſand are not worth one. This difference
hath dependence upon the different abilities of their
ctuals; which I reduce to the being, or not being a
pher; in regard that Philoſophy as being the proper food of
ſuch as live by it, diſtinguiſheth a Man from the common
ſence of the Vulgar in a more or leſs honourable degree
ing to the variety of that diet. In this ſence he that hath the
higheſt looks, is of higheſt quality; and the turning over of
the great Volume of Nature, which is the proper Object of
Philoſophy is the way to make one look high: in which Book,
although whatſoever we read, as being the Work of
mighty God, is therefore moſt proportionate; yet
ſtanding that is more abſolute and noble wherein we more
plainly deſerne his art and skill. The Conſtitution of the Vnivers,
among all Phyſical points that fall within Humane
henſion, may, in my opinion, be preferred to the Precedency:
for if that in regard of univerſal extent it excell all others, it
ought as the Rule and Standard of the reſt to goe before
them in Nobility. Now if ever any perſons might challenge
to be ſignally diſtinguiſhed for Intellectuals from other men;
1Ptolomey and Copernicus were they that have had the honour to
ſee fartheſt into, and diſcourſe moſt profoundly of the Worlds
Syſteme. About the Works of which famous Men theſe
lous being chiefly converſant, I conceived it my duty to
dicate them only to Your Highneſs. For laying all the weight
upon theſe two, whom I hold to be the Ableſt Wits that
have left us their Works upon theſe Subjects; to avoid a
ciſmein Manners, I was obliged to addreſs them to Him, who
with me, is the Greateſt of all Men, from whom they can
ceive either Glory or Patrociny. And if theſe two perſons
have ſo farre illuminated my Underſtanding as that this my
Book may in a great part be confeſſed to belong to them, well
may it alſo be acknowledged to belong to Your Highneſs, unto
whoſe Bounteous Magnificence I owe the time and leaſure I
had to write it, as alſo unto Your Powerful Aſſiſtance, (never
weary of honouring me) the means that at length I have had
to publiſh it. May Your Highneſs therefore be pleaſed to accept
of it according to Your accuſtomed Goodneſs; and if any
thing ſhall be found therein, that may be ſubſervient towards
the information or ſatisfaction of thoſe that are Lovers of
Truth; let them acknowledge it to be due to Your Self, who are
ſo expert in doing good, that Your Happy Dominion cannot
ſhew the man that is concerned in any of thoſe general
mities that diſturb the World; ſo that Praying for Your
rity, and continuance in this Your Pious and Laudable
ſtome, I humbly kiſs Your Hands;
Your Moſt Serene Highneſſes
Moſt Humble and moſt devoted
Servant and Subject
GALILEO GALILEI.
1
THE AUTHOR'S
INTRODUCTION.
Judicious Reader,
There was publiſhed ſome years ſince in Rome a ſalutiferous Edict, that, for
the obviating of the dangerous Scandals of the preſent Age, impoſed a
ſonable Silence upon the Pythagorean Opinion of the Mobility of the Earth.
There want not ſuch as unadviſedly affirm, that that Decree was not the
ction of a ſober Scrutiny, but of an ill informed Paſsion; & one may hear ſome
ter that Conſultors altogether ignorant of Aſtronomical Obſervations ought not
to clipp the Wings of Speculative Wits with raſh Prohibitions. My zeale
not keep ſilence when I hear theſe inconſiderate complaints. I thought fit, as being thoroughly
quainted with that prudent Determination, to appear openly upon the Theatre of the World as a
neſs of the naked Truth. I was at that time in Rome; and had not only the audiences, but applauds of
the moſt Eminent Prelates of that Court; nor was that Decree Publiſhed without Previous Notice given
me thereof. Therefore it is my reſolution in the preſent caſe to give Foraign Nations to ſee that this
point is as well under stood in Italy, and particularly in Rome, as Tranſalpine Diligence can imagine
it to be: and collecting together all the proper Speculations that concern the Copernican Syſteme,
to let them know, that the notice of all preceded the Cenſure of the Roman Court; and that there
proceed from this Climate not only Doctrines for the health of the Soul, but alſo ingenious Diſcoveries
for the recreating of the Mind.
To this end I have perſonated the Copernican in this Diſcourſe; proceeding upon an Hypotheſis
purely Mathematical; ſtriving by all artificial wayes to repreſent it Superiour, not to that of the
mobility of the Earth abſolutely, but according as it is mentioned by ſome, that retein no more, but the
name of Peripateticks, and are content, without going farther, to adore Shadows, not philoſophizing
with requiſit caution, but with the ſole remembrance of four Principles, but badly under ſtood.
We ſhall treat of three principall heads. Firſt I will endeavour to ſhew that all Experiments that can
be made upon the Earth are inſufficient means to conclude it's Mobility, but are indifferently applicable
to the Earth moveable or immoveable: and I hope that on this occaſion we ſhall diſcover many
vable paſſages unknown to the Ancients. Secondly we will examine the Cœleſtiall Phœnomena
that make for the Copernican Hypotheſis, as if it were to prove abſolutely victorious; adding by the
way certain new Obſervations, which yet ſerve only for the Aſtronomical Facility, not for Natural
Neceßity. In the third place I will propoſe an ingenuous Fancy. I remember that I have ſaid many
years ſince, that the unknown Probleme of the Tide might receive ſome light, admitting the Earths
Motion. This Poſition of mine paſsing from one to another had found charitable Fathers that
adopted it for the Iſſue of their own wit. Now, becauſe no ſtranger may ever appear that defending
ſelf with our armes ſhall charge us with want of caution in ſo principal an Accident, I have thought
good to lay down thoſe probabilities that would render it credible, admitting that the Earth did
move. I hope, that by theſe Conſider ations the World will come to know, that if other Nations have
Navigated more than we, we have not ſtudied leſs than they; & that our returning to aſſert the Earths
Stability, and to take the contrary only for a Mathematical Capriccio, proceeds not from inadvertency
of what others have thought thereof, but (had we no other inducements) from thoſe Reaſons that
ty, Religion, the Knowledge of the Divine Omnipotency, and a conſciouſneſs of the incapacity of mans
Vnderſtanding dictate unto us.
1
With all I conceived it very proper to expreſs theſe conceits by way of Dialogue, which, as not being
bound up to the riggid obſervance of Mathematical Laws, gives place alſo to Digreſsions that are
ſometimes no leſs curious than the principal Argument.
I chanced to be ſeveral years ſince, at ſeveral times, in the Stupendious Citty of Venice, where I
converſed with Signore Giovan Franceſco Sagredo of a Noble Extraction, and piercing wit. There
came thither from Florence at the ſame time Signore Filippo Salviati, whoſe leaſt glory was the
nence of his Blood, and Magnificence of his Eſtate: a ſublime Wit that fed not more hungerly upon
any pleaſure than on elevated Speculations. In the company of theſe two I often diſcourſed of theſe
matters before a certain Peripatetick Philoſopher who ſeemed to have no geater obſtacle in
ing of the Truth, than the Fame he had acquired by Ariſtotelical Interpretations.
Now, ſeeing that inexorable Death hath deprived Venice and Florence of thoſe two great Lights in
the very Meridian of their years, I did reſolve, as far as my poor ability would permit, to perpetuate
their lives to their honour in theſe leaves, bringing them in as Interlocutors in the preſent Controverſy.
Nor ſhall the Honest Peripatetick want his place, to whom for his exceſsive affection to wards the
mentaries of Simplicius, I thought fit, without mentioning his own Name, to leave that of the Author
he ſo much reſpected. Let thoſe two great Souls, ever venerable to my heart, pleaſe to accept this
blick Monument of my never dying Love; and let the remembr ance of their Eloquence aſsiſt me in
delivering to Poſterity the Conſider ations that I have promiſed.
There caſually happened (as was uſuall) ſeveral diſcourſes at times between theſe Gentlemen, the
which had rather inflamed than ſatisfied in their wits the thirſt they had to be learning; whereupon
they took a diſcreet reſolution to meet together for certain dayes, in which all other buſineſs ſet aſide,
they might betake themſelves more methodically to contemplate the Wonders of God in Heaven, and in
the Earth: the place appointed for their meeting being in the Palace of the Noble Sagredo, after the
due, but very ſhort complements; Signore Salviati began in this manner.
1
GALILÆUS
Galilæus Lyncæus,
HIS
SYSTEME
OF THE
WORLD.
The Firſt Dialogue.
INTERLOCVTORS.
SALVIATUS, SAGREDUS, and SIMPLICIUS.
SALVIATUS.
It was our yeſterdayes reſolution, and
greement, that we ſhould to day diſcourſe
the moſt diſtinctly, and particularly we
could poſſible, of the natural reaſons, and
their efficacy that have been hitherto
ledged on the one or other part, by the
maintainers of the Poſitions, Aristotelian,
and Ptolomaique; and by the followers

of the Copernican Syſteme: And becauſe
Copernicus placing the Earth among the moveable Bodies of
ven, comes to conſtitute a Globe for the ſame like to a Planet; it
would be good that we began our diſputation with the
tion of what, and how great the energy of the Peripateticks
guments is, when they demonſtrate, that this Hypotheſis is
1ſible: Since that it is neceſſary to introduce in Nature, ſubſtances

different betwixt themſelves, that is, the Cœleſtial, and
ry; that impaſſible and immortal, this alterable and corruptible.
Which argument Ariſtotle handleth in his book De Cœlo,
ating it firſt, by ſome diſcourſes dependent on certain general
ſumptions, and afterwards confirming it with experiments and
ticular demonſtrations: following the ſame method, I will
pound, and freely ſpeak my judgement, ſubmitting my ſelf to
your cenſure, and particularly to Simplicius, a Stout Champion
and contender for the Ariſtotelian
Copernicus
teth the earth œ
Globe like to a
net.
Cœleſtial
ces that are
rable, and
tary that be
rable, are neceſſary
in the opinion of
Ariſtotle.
Ariſtotle maketh
the World perfect,
becauſe it hath the
threefold
on.
And the firſt Step of the Peripatetick arguments is that, where
riſtotle proveth the integrity and perfection of the World, telling
us, that it is not a ſimple line, nor a bare ſuperficies, but a body
adorned with Longitude, Latitude, and Profundity; and becauſe
there are no more dimenſions but theſe three; The World having
them, hath all, and having all, is to be concluded perfect. And
again, that by ſimple length, that magnitude is conſtituted, which
is called a Line, to which adding breadth, there is framed the
perficies, and yet further adding the altitude or profoundity, there
reſults the Body, and after theſe three dimenſions there is no
paſſing farther, ſo that in theſe three the integrity, and to ſo ſpeak,
totality is terminated, which I might but with juſtice have
red Ariſtotle to have proved to me by neceſſary conſequences, the
rather in regard he was able to do it very plainly, and ſpeedily.
SIMPL. What ſay you to the excellent demonſtrations in the

2. 3. and 4. Texts, after the definition of Continual? have you it
not firſt there proved, that there is no more but three dimenſions,
for that thoſe three are all things, and that they are every where?
And is not this confirmed by the Doctrine and Authority of the

Pythagorians, who ſay that all things are determined by three,
ginning, middle, and end, which is the number of All? And where
leave you that reaſon, namely, that as it were by the law of
ture, this number is uſed in the ſacrifices of the Gods? And why
being ſo dictated by nature, do we atribute to thoſe things that
are three, and not to leſſe, the title of all? why of two is it ſaid
both, and not all, unleſs they be three? And all this Doctrine you
have in the ſecond Text. Afterwards in the third, Ad pleniorem

ſcientiam, we read that All, the Whole, and Perfect, are formally
one and the ſame; and that therefore onely the Body, amongſt
magnitudes is perfect: becauſe it is determined by three, which is
All, and being diviſible three manner of waies, it is every way
viſible; but of the others, ſome are dividible in one manner, and
ſome in two, becauſe according to the number aſſixed, they have
their diviſion and continuity, and thus one magnitude is

ate one way, another two, a third, namely the Body, every way.
1Moreover in the fourth Text; doth he not after ſome other
ctrines, prove it by another demonſtration? Scilicet, That no
ſition is made but according to ſome defect (and ſo there is a
ſition or paſſing from the line to the ſuperficies, becauſe the line is
defective in breadth) and that it is impoſſible for the perfect to
want any thing, it being every way ſo; therefore there is no
ſition from the Solid or Body to any other magnitude. Now
think you not that by all theſe places he hath ſufficiently proved,
how that there's no going beyond the three dimenſions, Length,
Breadth, and Thickneſs, and that therefore the body or ſolid,
which hath them all, is perfect?
Ariſtotles
ſtrations to prove
the dimenſions to be
three and no more.
The number three
celebrated among ſt
the Pythagorians
Omne, Totum &
Perfectum.
Or Solid.
SALV. To tell you true, I think not my ſelf bound by all theſe
reaſons to grant any more but onely this, That that which hath
beginning, middle, and end, may, and ought to be called perfect: But
that then, becauſe beginning, middle, and end, are Three, the
ber Three is a perfect number, and hath a faculty of conferring
Perfection on thoſe things that have the ſame, I find no inducement
to grant; neither do I underſtand, nor believe that, for example,
of feet, the number three is more perfect then four or two, nor do
I conceive the number four to be any imperfection to the
ments: and that they would be more perfect if they were three.
Better therefore it had been to have left theſe ſubtleties to the
Rhetoricians, and to have proved his intent, by neceſſary
tion; for ſo it behoves to do in demonſtrative ſciences.
SIMPL. You ſeem to ſcorn theſe reaſons, and yet it is all the
Doctrine of the Pythagorians, who attribute ſo much to numbers;
and you that be a Mathematician, and believe many opinions in
the Pythagorick Philoſophy, ſeem now to contemn their
ſteries.
SALV. That the Pythagorians had the ſcience of numbers in
high eſteem, and that Plato himſelf admired humane
ing, and thought that it pertook of Divinity, for that it

ſtood the nature of numbers, I know very well, nor ſhould I be
far from being of the ſame opinion: But that the Myſteries for
which Pythagoras and his ſect, had the Science of numbers in ſuch
veneration, are the follies that abound in the mouths and writings

of the vulgar, I no waies credit: but rather becauſe I know that they,
to the end admirable things might not be expoſed to the
tempt, and ſcorne of the vulgar, cenſured as ſacrilegious, the

liſhing of the abſtruce properties of Numbers, and
ſurable and irrational quantities, by them inveſtigated; and
vulged, that he who diſcovered them, was tormented in the other
World: I believe that ſome one of them to deter the common
ſort, and free himſelf from their inquiſitiveneſs, told them that the
myſteries of numbers were thoſe trifles, which afterwards did ſo
1ſpread amongſt the vulgar; and this with a diſcretion and ſubtlety
reſembling that of the prudent young man, that to be freed
from the importunity of his inquiſitive Mother or Wife, I know
not whether, who preſſed him to impart the ſecrets of the Senate,
contrived that ſtory, which afterwards brought her and many
ther women to be derided and laught at by the ſame Senate.
Plato held that
humane
ſtanding partook
of divinity, becauſe
it understood
bers.
The Myſtery of
Pythagorick
bers fabulous.
De Papyrio
textato, Gellius
2. 3.
SIMPL. I will not be of the number of thoſe who are over
ous about the Pythagorick myſteries; but adhering to the point
in hand; I reply, that the reaſons produced by Ariſtotle to prove
the dimenſions to be no more than three, ſeem to me
dent, and I believe, That had there been any more evident
ſtrations thereof, Ariſtotle would not have omitted them.
SAGR. Put in at leaſt, if he had known, or remembred any more.
But you Salviatus would do me a great pleaſure to alledge unto
me ſome arguments that may be evident, and clear enough for me
to comprehend.
SALV. I will; and they ſhall be ſuch as are not onely to be
prehended by you, but even by Simplicius himſelf: nor onely
to be comprehended, but are alſo already known, although
ly unobſerved; and for the more eaſie underſtanding thereof,
we will take this Pen and Ink, which I ſee already prepared for

ſuch occaſions, and deſcribe a few figures. And firſt we will note
[Fig. 1. at the end of this Dialog.] theſe two points AB, and draw
from the one to the other the curved lines, ACB, and ADB, and the
right line A B, I demand of you which of them, in your mind, is
that which determines the diſtance between the terms AB, & why?
A Geometrical
monſtration of the
triple dimenſion.
SAGR. I ſhould ſay the right line, and not the crooked, as well
becauſe the right is ſhorter, as becauſe it is one, ſole, and
minate, whereas the others are infinit, unequal, and longer; and my
determination is grounded upon that, That it is one, and certain.
SALV. We have then the right line to determine the length
tween the two terms; let us add another right line and parallel to
AB, which let be CD, [Fig. 2.] ſo that there is put between them a
ſuperficies, of which I deſire you to aſſign me the breadth, therefore
departing from the point A, tell me how, and which way you will
go, to end in the line C D, and ſo to point me out the breadth
prehended between thoſe lines; let me know whether you will
terminate it according to the quantity of the curved line A E, or
the right line A F, or any other.
SIMPL. According to the right A F, and not according to the
crooked, that being already excluded from ſuch an uſe.
SAGR. But I would take neither of them, ſeeing the right line
A F runs obliquely; But would draw a line, perpendicular to C
D, for this ſhould ſeem to me the ſhorteſt, and the propereſt of
infinite that are greater, and unequal to one another, which may be
1produced from the term A to any other part of the oppoſite line
C D.
SALV. Your choice, and the reaſon you bring for it in my
ment is moſt excellent; ſo that by this time we have proved that
the firſt dimenſion is determined by a right line, the ſecond
ly the breadth with another line right alſo, and not onely right,
but withall, at right-angles to the other that determineth the
length, and thus we have the two dimenſions of length and
breadth, definite and certain. But were you to bound or
nate a height, as for example, how high this Roof is from the
ment, that we tread on, being that from any point in the Roof,
we may draw infinite lines, both curved, and right, and all of
verſe lengths to infinite points of the pavement, which of all theſe
lines would you make uſe of?
SAGR. I would faſten a line to the Seeling, and with a plummet
that ſhould hang at it, would let it freely diſtend it ſelf till it
ſhould reach well near to the pavement, and the length of ſuch a
thread being the ſtreighteſt and ſhorteſt of all the lines, that could
poſsibly be drawn from the ſame point to the pavement, I would
ſay was the true height of this Room.
SALV. Very well, And when from the point noted in the
ment by this pendent thread (taking the pavement to be levell
and not declining) you ſhould produce two other right lines, one
for the length, and the other for the breadth of the ſuperficies of
theſaid pavement, what angles ſhould they make with the ſaid
thread?
SAGR. They would doubtleſs meet at right angles, the ſaid
lines falling perpendicular, and the pavement being very plain and
levell.
SALV. Therefore if you aſſign any point, for the term from whence
to begin your meaſure; and from thence do draw a right line, as
the terminator of the firſt meaſure, namely of the length, it will
follow of neceſſity, that that which is to deſign out the largeneſs
or breadth, toucheth the firſt at right-angles, and that that which is
to denote the altitude, which is the third dimenſion, going from the
ſame point formeth alſo with the other two, not oblique but right
angles, and thus by the three perpendiculars, as by three lines, one,
certain, and as ſhort as is poſſible, you have the three dimenſions
A B length, A C breadth, and A D height; and becauſe, clear it
is, that there cannot concurre any more lines in the ſaid point, ſo
as to make therewith right-angles, and the dimenſions ought to
be determined by the ſole right lines, which make between
ſelves right-angles; therefore the dimenſions are no more but
three, and that which hath three hath all, and that which hath all,
is diviſible on all ſides, and that which is ſo, is perfect, &c.
1
SIMPL. And who ſaith that I cannot draw other lines? why
may not I protract another line underneath, unto the point A,
that may be perpendicular to the reſt?
SALV. You can doubtleſs, at one and the ſame point, make no
more than three right lines concurre, that conſtitute right angles
between themſelves.
SAGR. I ſee what Simplicius means, namely, that ſhould the
ſaid D A be prolonged downward, then by that means there might
be drawn two others, but they would be the ſame with the firſt
three, differing onely in this, that whereas now they onely touch,
then they would interſect, but not produce new
In phyfical proofs
geometrical
neſs is not
ry.
SIMPL. I will not ſay that this your argument may not be
cludent; but yet this I ſay with Ariſtotle, that in things natural
it is not alwaies neceſſary, to bring Mathematical demonſtrations.
SAGR. Grant that it were ſo where ſuch proofs cannot be had,
yet if this caſe admit of them, why do not you uſe them? But it
would be good we ſpent no more words on this particular, for I
think that Salviatus will yield, both to Ariſtotle, and you,
out farther demonſtration, that the World is a body, and perfect,
yea moſt perfect, as being the greateſt work of God.
SALV. So really it is, therefore leaving the general contempla­

tion of the whole, let us deſcend to the conſideration of its parts,
which Ariſtotle, in his firſt diviſion, makes two, and they very
rent and almoſt contrary to one another; namely the Cœleſtial,
and Elementary: that ingenerable, incorruptible, unalterable,
paſſible, &c. and this expoſed to a continual alteration,
on, &c. Which difference, as from its original principle, he
rives from the diverſity of local motions, and in this method he
proceeds.
Parts of the world
are two, according
to Ariſtotle,
ſtial and
tary contrary to
one another.
Leaving the ſenſible, if I may ſo ſpeak, and retiring into the
Ideal world, he begins Architectonically to conſider that nature
being the principle of motion, it followeth that natural bodies be

indued with local motion. Next he declares local motion to be
of three kinds, namely, circular, right, and mixt of right and
cular: and the two firſt he calleth ſimple, for that of all lines the

circular, and right are onely ſimple; and here ſomewhat
ſtraining himſelf, he defineth anew, of ſimple motions, one to be
circular, namely that which is made about the medium, and the
other namely the right, upwards, and downwards; upwards, that
which moveth from the medium; downwards, that which goeth
wards the medium. And from hence he infers, as he may by and

ceſſary conſequence, that all ſimple motions are confined to theſe
three kinds, namely, to the medium, from the medium, and about
the medium; the which correſponds ſaith he, with what hath been
ſaid before of a body, that it alſo is perfected by three things, and ſo
1is its motion. Having confirmed theſe motions, he proceeds ſaying,
that of natural bodies ſome being ſimple, and ſome compoſed of
them (and he calleth ſimple bodies thoſe, that have a principle
of motion from nature, as the Fire and Earth) it follows that
ſimple motions belong to ſimple bodies, and mixt to the
pound; yet in ſuch ſort, that the compounded incline to the part
predominant in the compoſition.
Local motion of
three kinds, right,
circular, & mixt.
Circular, and
ſtreight motions
are ſimple, as
ceeding by ſimple
lines.
Ad medium, à
dio, & circa
um.
SAGR. Pray you hold a little Salviatus, for I find ſo many
doubts to ſpring up on all ſides in this diſcourſe, that I ſhall be
conſtrained, either to communicate them if I would attentively
hearken to what you ſhall add, or to take off my attention from
the things ſpoken, if I would remember objections.
SALV. I will very willingly ſtay, for that I alſo run the ſame
hazard, and am ready at every ſtep to loſe my ſelf whilſt I ſail
tween Rocks, and boiſterous Waves, that make me, as they ſay, to
loſe my Compaſs; therefore before I make them more, propound
your
The definition of
Nature, either
perfect, or
nable, produced by
Ariſtotle.
SAGR. You and Ariſtotle together would at firſt take me a
little out of the ſenſible World, to tell me of the Architecture,
wherewith it ought to be fabricated; and very appoſitly begin to
tell me, that a natural body is by nature moveable, nature being
(as elſewhere it is defined) the principle of motion. But here I
am ſomewhat doubtfull why Ariſtotle ſaid not that of natural
dies, ſome are moveable by nature, and others immoveable, for
that in the definition, nature is ſaid to be the principle of Motion,
and Reſt; for if natural bodies have all a principle of motion,
either he might have omitted the mention of Reſt, in the
on of nature: or not have introduced ſuch a definition in this place.
Next, as to the declaration of what Ariſtotle intends by ſimple
motions, and how by Spaces he determines them, calling thoſe
ple, that are made by ſimple lines, which are onely the right, and

circular, I entertain it willingly; nor do I deſire to tenter the
inſtance of the Helix, about the Cylinder; which in that it is in
very part like to it ſelf, might ſeemingly be numbred among
ple lines. But herein I cannot concurre, that he ſhould ſo
ſtrain ſimple motions (whilſt he ſeems to go about to repeat the
ſame definition in other words) as to call one of them the motion
about the medium, the others Surſum & Deorſum, namely
wards and downward; which terms are not to be uſed, out of the
World fabricated, but imply it not onely made, but already
habited by us; for if the right motion be ſimple, by the ſimplicity
of the right line, and if the ſimple motion be natural, it is made on
every ſide, to wit, upwards, downwards, backwards, forwards, to
the right, to the left, and if any other way can be imagined,
vided it be ſtraight, it ſhall agree to any ſimple natural body; or
1if not ſo, then the ſuppoſion of Ariſtotle is defective. It appears

moreover that Ariſtotle hinteth but one circular motion alone to
be in the World, and conſequently but one onely Center, to
which alone the motions of upwards and downwards, refer. All
which are apparent proofs, that Ariſtotles aim is, to make white
black, and to accommodate Architectur to the building, and not
to modle the building according to the precepts of Arthitecture:
for if I ſhould ſay that Nature in Univerſal may have a
ſand Circular Motions, and by conſequence a thouſand
ters, there would be alſo a thouſand motions upwards, and
downwards. Again he makes as hath been ſaid, a ſimple motion,
and a mixt motion, calling ſimple, the circular and right; and
mixt, the compound of them two: of natural bodies he calls ſome
ſimple (namely thoſe that have a natural principle to ſimple
tion) and others compound: and ſimple motions he attributes
to ſimple bodies, and the compounded to the compound; but by
compound motion he doth no longer underſtand the mixt of right
and circular, which may be in the World; but introduceth a mixt
motion as impoſſible, as it is impoſſible to mixe oppoſite motions
made in the ſame right line, ſo as to produce from them a motion
partly upwards, partly downwards; and, to moderate ſuch an
ſurdity, and impoſſibility, he aſſerts that ſuch mixt bodies move

according to the ſimple part predominant: which neceſſitates
others to ſay, that even the motion made by the ſame right line is
ſometimes ſimple, and ſometimes alſo compound: ſo that the
plicity of the motion, is no longer dependent onely on the
plicity of the line.
The Helix about
the Cylinder may
be ſaid to be a
ple line.
Ariſtotle
modates the rules of
Architecture to
the frame of the
World, and not the
frame to the rules.
Right motion,
times ſimple, ard
ſometimes mixt
cording to Ariſt.
SIMPL. How? Is it not difference ſufficient, that the ſimple and
abſolute are more ſwift than that which proceeds from
nion? and how much faſter doth a piece of pure Earth deſcend,
than a piece of Wood?
SAGR. Well, Simplicius; But put caſe the ſimplicity for this
cauſe was changed, beſides that there would be a hundred
ſand mixt motions, you would not be able to determine the
ple; nay farther, if the greater or leſſe velocity be able to alter
the ſimplicity of the motion, no ſimple body ſhould move with a
ſimple motion; ſince that in all natural right motions, the
ty is ever encreaſing, and by conſequence ſtill changing the
city, which as it is ſimplicity, ought of conſequence to be
table, and that which more importeth, you charge Ariſtotle with
another thing, that in the definition of motions compounded, he
hath not made mention of tardity nor velocity, which you now
inſert for a neceſſary and eſſential point. Again you can draw
no advantage from this rule, for that there will be amongſt the
mixt bodies ſome, (and that not a few) that will move ſwiftly,
1and others more ſlowly than the ſimple; as for example, Lead, and
Wood, in compariſon of earth; and therefore amongſt theſe
tions, which call you the ſimple, and which the mixt?
SIMPL. I would call that ſimple motion, which is made by a
ſimple body, and mixt, that of a compound body.
SAGR. Very well, and yet Simplicius a little before you ſaid,
that the ſimple, and compound motions, diſcovered which were
mixt, and which were ſimple bodies; now you will have me by
ſimple and mixt bodies, come to know which is the ſimple, and
which is the compound motion: an excellent way to keep us
rant, both of motions and bodies. Moreover you have alſo a little
above declared, how that a greater velocity did not ſuffice, but
you ſeek a third condition for the definement of ſimple motion, for
which Ariſtotle contented himſelf with one alone, namely, of the
ſimplicity of the Space, or Medium: But now according to you,
the ſimple motion, ſhall be that which is made upon a ſimple line,
with a certain determinate velocity, by a body ſimply moveable.
Now be it as you pleaſe, and let us return to Ariſtotle, who
neth the mixt motion to be that compounded of the right, and
cular, but produceth not any body, which naturally moveth with
ſuch a motion.
SALV. I come again to Ariſtotle, who having very well, and
Methodically begun his diſcourſe, but having a greater aim to
reſt at, and hit a marke, predefigned in his minde, then that to
which his method lead him, digreſſing from the purpoſe, he comes
to aſſert, as a thing known and manifeſt, that as to the motions
directly upwards or downwards, they naturally agree to Fire, and
Earth; and that therefore it is neceſſary, that beſides theſe bodies,
which are neer unto us, there muſt be in nature another, to which
the circular motion may agree: which ſhall be ſo much the more
excellent by how much the circular motion is more perfect, then the
ſtreight, but how much more perfect that is than this, he
mines from the greatneſs of the circular lines perfection above the

right line; calling that perfect, and this imperfect; imperfect,
cauſe if infinite it wanteth a termination, and end: and if it be
nite, there is yet ſomething beyond which it may be prolonged.
This is the baſis, ground work, and maſter-ſtone of all the Fabrick
of the Aristotelian World, upon which they ſuperſtruct all their
other properties, of neither heavy nor light, of ingenerable
ruptible, exemption from all motions, ſome onely the local, &c.
And all theſe paſſions he affirmeth to be proper to a ſimple body
that is moved circularly; and the contrary qualities of gravity,
levity, corruptibility, &c. he aſſigns to bodies naturally moveable
in a ſtreight line, for that if we have already diſcovered defects in
the foundation, we may rationally queſtion what ſoever may
1ther built thereon. I deny not, that this which Ariſtotle hitherto
hath introduced, with a general diſcourſe dependent upon
ſal primary principles, hathbeen ſince in proceſs of time, re-inforced
with particular reaſons, and experiments; all which it would be
neceſſary diſtinctly to conſider and weigh; but becauſe what hath
been ſaid hitherto preſents to ſuch as conſider the ſame many and
no ſmall difficulties, (and yet it would be neceſſary, that the
mary principles and fundamentals, were certain, firm, and
ed, that ſo they might with more confidence be built upon) it
would not be amiſs, before we farther multiply doubts, to ſee if
haply (as I conjecture) betaking our ſelves to other waies, we may
not light upon a more direct and ſecure method; and with better
conſidered principles of Architecture lay our primary
tals. Therefore ſuſpending for the preſent the method of
tle, (which we will re-aſſume again in its proper place, and
cularly examine;) I ſay, that in the things hitherto affirmed by

him, I agree with him, and admit that the World is a body
ing all dimenſions, and therefore moſt perfect; and I add, that as
ſuch, it is neceſſarily moſt ordinate, that is, having parts between
themſelves, with exquiſite and moſt perfect order diſpoſed; which
aſſumption I think is not to be denied, neither by you or any
other.
The circular line
perfect, according
to Ariſtotle, and
but the right
perfect, and why.
The world is
poſed by the
thor to be perfectly
ordinate.
SIMPL. Who can deny it? the firſt particular (of the worlds
dimenſions) is taken from Ariſtotle himſelf, and its
on of ordinate ſeems onely to be aſſumed from the order which it
moſt exactly
Streight motion
impoſſible in the
world exactly
dinate.
SALV. This principle then eſtabliſhed, one may immediately
conclude, that if the entire parts of the World ſhould be by their
nature moveable, it is impoſſible that their motions ſhould be
right, or other than circular; and the reaſon is ſufficiently eaſie,
and manifeſt; for that whatſoever moveth with a right motion,
changeth place; and continuing to move, doth by degrees more
and more remove from the term from whence it departed, and
from all the places thorow which it ſucceſſively paſſed; and if
ſuch motion naturally ſuited with it, then it was not at the
ginning in its proper place; and ſo the parts of the World were
not diſpoſed with perfect order. But we ſuppoſe them to be
fectly ordinate, therefore as ſuch, it is impoſſible that they ſhould
by nature change place, and conſequently move in a right moti­

on. Again, the right motion being by nature infinite, for that
the right line is infinite and indeterminate, it is impoſſible that

any moveable can have a natural principle of moving in a right
line; namely toward the place whither it is impoſſible to arrive,

there being no præ-ſinite term; and nature, as Ariſtotle himſelf
ſaith well, never attempts to do that which can never be done,
1nor eſſaies to move whither it is impoſſible to arrive. And if any
one ſhould yet object, that albeit the right line, and
ly the motion by it is producible in infinitum, that is to ſay, is
terminate; yet nevertheleſs Nature, as one may ſay, arbitrarily
hath aſſigned them ſome terms, and given natural inſtincts to
its natural bodies to move unto the ſame; I will reply, that this

might perhaps be fabled to have come to paſs in the firſt Chaos,
where indiſtinct matters confuſedly and inordinately wandered;
to regulate which, Nature very appoſitely made uſe of right

tions, by which, like as the well-conſtituted, moving, diſdorder
themſelves, ſo were they which were before depravedly diſpoſed
by this motion ranged in order: but after their exquiſite
tion and collocation, it is impoſſible that there ſhould remain
tural inclinations in them of longer moving in a right motion,
from which now would enſue their removal from their proper and
natural place, that is to ſay, their diſordination; we may
fore ſay that the right motion ſerves to conduct the matter to erect
the work; but once erected, that it is to reſt immoveable, or if

moveable, to move it ſelf onely circularly. Unleſs we will ſay
with Plato, that theſe mundane bodies, after they had been made
and finiſhed, were for a certain time moved by their Maker, in a
right motion, but that after their attainment to certain and
terminate places, they were revolved one by one in Spheres,
ſing from the right to the circular motion, wherein they have
been ever ſince kept and maintained. A ſublime conceipt, and

worthy indeed of Plato: upon which, I remember to have heard
our common friend the ^{*}Lyncean Academick diſcourſe in this
ner, if I have not forgot it. Every body for any reaſon
ted in a ſtate of reſt, but which is by nature moveable, being ſet

at liberty doth move; provided withal, that it have an
tion to ſome particular place; for ſhould it ſtand indifferently
fected to all, it would remain in its reſt, not having greater
ducement to move one way than another. From the having of
this inclination neceſſarily proceeds, that it in its moving ſhall

tinually increaſe its acceleration, and beginning with a moſt ſlow
motion, it ſhall not acquire any degree of velocity, before it
ſhall have paſſed thorow all the degrees of leſs velocity, or
ter tardity: for paſſing from the ſtate of quiet (which is the

finite degree of tardity of motion) there is no reaſon by which
it ſhould enter into ſuch a determinate degree of velocity, before
it ſhall have entred into a leſs, and into yet a leſs, before it entred
into that: but rather it ſtands with reaſon, to paſs firſt by thoſe
degrees neareſt to that from which it departed, and from thoſe to
the more remote; but the degree from whence the moveable

began to move, is that of extreme tardity, namely of reſt.
1
Now this acceleration of motion is never made, but when the
moveable in moving acquireth it; nor is its acquiſt other than an
approaching to the place deſired, to wit, whither its natural
clination attracts it, and thither it tendeth by the ſhorteſt way;
namely, by a right line. We may upon good grounds therefore
ſay, That Nature, to confer upon a moveable firſt conſtituted in
reſt a determinate velocity, uſeth to make it move according to

a certain time and ſpace with a right motion. This preſuppoſed,
let us imagine God to have created the Orb v. g. of Jupiter, on
which he had determined to confer ſuch a certain velocity, which
it ought afterwards to retain perpetually uniform; we may with
Plato ſay, that he gave it at the beginning a right and accelerate
motion, and that it afterwards being arrived to that intended

gree of velocity, he converted its right, into a circular motion,
the velocity of which came afterwards naturally to be uniform.
Right motion by
nature infinite.
Motion by a right
line naturally
poſſible.
Nature attempts
not things
ble to be effected.
Right motion might
perhaps be in the
firſt Chaos.
Right motion is
commodious to
range in order,
things ous of
der.
Mundane bodies
moved in the
ginning in a right
line, and
wards circularly?
according to Plato.
* Thus doth he
vertly and
ly ſtile himſelfe
throughout this
work.
A moveable
ing in a ſtate of
reſt, ſhall not move
unleſs it have an
inclination to ſome
particular place.
The moveable
celerates its
on, going towards
the place whither
it hath an
tion.
The moveable
ſing from reſt,
eth thorow all the
degrees of tardity.
Reſt the inſinioe
degree of tardity.
The moveable doth
not accelerate, ſave
only as it
eth nearer to its
term.
Nature, to
duce in the
able a certain
gree of velocity,
made it move in a
right line.
Vniform velocity
convenient to the
circular motion.
SAGR. I hearken to this Diſcourſe with great delight; and I
believe the content I take therein will be greater, when you have
ſatisfied me in a doubt: that is, (which I do not very well
prehend) how it of neceſſity enſues, that a moveable departing

from its reſt, and entring into a motion to which it had a natural
inclination, it paſſeth thorow all the precedent degrees oſ tardity,
comprehended between any aſſigned degree of velocity, and the
ſtate of reſt, which degrees are infinite? ſo that Nature was not
able to confer them upon the body of Jupiter, his circular
on being inſtantly created with ſuch and ſuch
Betwixt reſt, and
any aſſigned degree
of velocity, infinite
degrees of leſs
locity interpoſe.
Nature doth not
immediately
fer a determinate
degree of velocity,
howbeit ſhe could.
SALV. I neither did, nor dare ſay, that it was impoſſible for
God or Nature to confer that velocity which you ſpeak of,
diately; but this I ſay, that de facto ſhe did not doit; ſo that the
doing it would be a work extra-natural, and by confequence
raculous.
SAGR. Then you believe, that a ſtone leaving its reſt, and
tring into its natural motion towards the centre of the Earth,
ſeth thorow all the degrees of tardity inferiour to any degree of
velocity?
SALV. I do believe it, nay am certain of it; and ſo certain,
that I am able to make you alſo very well ſatisfied with the truth
thereof.
SAGR. Though by all this daies diſcourſe I ſhould gain no
more but ſuch a knowledge, I ſhould think my time very well
beſtowed.
SALV. By what I collect from our diſcourſe, a great part of
your ſcruple lieth in that it ſhould in a time, and that very ſhort,
paſs thorow thoſe infinite degrees of tardity precedent to any
locity, acquired by the moveable in that time: and therefore
fore we go any farther, I will ſeek to remove this difficulty, which
1ſhall be an eaſie task; for I reply, that the moveable paſſeth by
the aforeſaid degrees, but the paſſage is made without ſtaying in

any of them; ſo that the paſſage requiring but one ſole inſtant
of time, and every ſmall time containing infinite inſtants, we ſhall
not want enough of them to aſſign its own to each of the infinite
degrees of tardity; although the time were never ſo ſhort.
The moveable
parting from reſv
paſſeth thorow all
degrees of velocity
without ſtaying in
any.
SAGR. Hitherto I apprehend you; nevertheleſs it is very much
that that Ball ſhot from a Cannon (for ſuch I conceive the
dent moveable) which yet we ſee to fall with ſuch a precipice,
that in leſs than ten pulſes it will paſs two hundred yards of
titude; ſhould in its motion be found conjoyned with ſo ſmall a
degree of velocity, that, ſhould it have continued to have moved
at that rate without farther acceleration, it would not have paſt
the ſame in a day.
SALV. You may ſay, nor yet in a year, nor in ten, no nor in a
thouſand; as I will endeavour to ſhew you, and alſo happily
out your contradiction, to ſome ſufficiently ſimple queſtions that
I will propound to you. Therefore tell me if you make any
ſtion of granting that, that that ball in deſcending goeth
ſing its impetus and velocity.
SAGR. I am moſt certain it doth.
SALV. And if I ſhould ſay that the impetus acquired in any
place of its motion, is ſo much, that it would ſuffice to re-carry
it to that place from which it came, would you grant it?
SAGR. I ſhould conſent to it without contradiction, provided
waies, that it might imploy without impediment its whole impetus
in that ſole work of re-conducting it ſelf, or another equal toit, to

that ſelf-ſame height as it would do, in caſe the Earth were bored
thorow the centre, and the Bullet fell a thouſand yards from the
ſaid centre, for I verily believe it would paſs beyond the centre,
aſcending as much as it had deſcended; and this I ſee plainly in
the experiment of a plummet hanging at a line, which removed
from the perpendicular, which is its ſtate of reſt, and afterwards
let go, falleth towards the ſaid perpendicular, and goes as far
yond it; or onely ſo much leſs, as the oppoſition of the air, and
line, or other accidents have hindred it. The like I ſee in the
ter, which deſcending thorow a pipe, re-mounts as much as it had
deſcended.
The ponderous
ver deſcending
quireth impetus
ſufficient to
carry it to the like
height.
SALV. You argue very well. And for that I know you will not
ſcruple to grant that the acquiſt of the impetus is by means of the
receding from the term whence the moveable departed, and its
proach to the centre, whither its motion tendeth; will you ſtick
to yeeld, that two equal moveables, though deſcending by divers
lines, without any impediment, acquire equal impetus, provided
that the approaches to the centre be equal?
1
SAGR. I do not very well underſtand the queſtion.
SALV. I will expreſs it better by drawing a Figure: therefore
I will ſuppoſe the line A B [in Fig. 3.] parallel to the Horizon,
and upon the point B, I will erect a perpendicular B C; and after
that I adde this ſlaunt line C A. Underſtanding now the line C
A to be an inclining plain exquiſitely poliſhed, and hard, upon
which deſcendeth a ball perfectly round and of very hard matter,
and ſuch another I ſuppoſe freely to deſcend by the perpendicular
C B: will you now confeſs that the impetus of that which
ſcends by the plain C A, being arrived to the point A, may be
equal to the impetus acquired by the other in the point B, after
the deſcent by the perpendicular C
The impetuoſity of
moveables equally
approaching to the
centre, are equal.
SAGR. I reſolutely believe ſo: for in effect they have both the
ſame proximity to the centre, and by that, which I have already
granted, their impetuoſities would be equally ſufficient to re-carry
them to the ſame height.
SALV. Tell me now what you believe the ſame ball would do
put upon the Horizontal plane A B?
Vpon an
tall plane the
able lieth ſtill.
SAGR. It would lie ſtill, the ſaid plane having no declination.
SALV. But on the inclining plane C A it would deſcend, but
with a gentler motion than by the perpendicular C B?
SAGR. I may confidently anſwer in the affirmative, it
ing to me neceſſary that the motion by the perpendicular C B
ſhould be more ſwift, than by the inclining plane C A; yet
vertheleſs, iſ this be, how can the Cadent by the inclination
rived to the point A, have as much impetus, that is, the ſame
gree of velocity, that the Cadent by the perpendicular ſhall have
in the point B? theſe two Propoſitions ſeem contradictory.
The veloeity by the
inclining plane
qual to the
ty by the
oular, and the
tion by the
dicular ſwifter
than by the
nation.
SALV. Then you would think it much more falſe, ſhould I
ſay, that the velocity of the Cadents by the perpendicular, and
inclination, are abſolutely equal: and yet this is a Propoſition
moſt true, as is alſo this that the Cadent moveth more ſwiftly by
the perpendicular, than by the inclination.
SAGR. Theſe Propoſitions to my ears ſound very harſh: and
I believe to yours Simplicius?
SIMPL. I have the ſame ſenſe of them.
SALV. I conceit you jeſt with me, pretending not to
hend what you know better than my ſelf: therefore tell me
plicius, when you imagine a moveable more ſwift than
ther, what conceit do you fancy in your mind?
SIMPL. I fancie one to paſs in the ſame time a greater ſpace
than the other, or to move equal ſpaces, but in leſſer time.
SALV. Very well: and for moveables equally ſwift, what's
your conceit of them?
SIMPL. I fancie that they paſs equal ſpaces in equal times.
1
SALV. And have you no other conceit thereof than this?
SIMPL. This I think to be the proper definition of equal
tions.
Velocities are ſaid
to be equal, when
the ſpaces paſſed
are proportionate to
their time.
SAGR. We will add moreover this other: and call that equal
velocity, when the ſpaces paſſed have the ſame proportion, as the
times wherein they are paſt, and it is a more univerſal definition.
SALV. It is ſo: for it comprehendeth the equal ſpaces paſt in
equal times, and alſo the unequal paſt in times unequal, but
portionate to thoſe ſpaces. Take now the ſame Figure, and
ing the conceipt that you had of the more haſtie motion, tell me
why you think the velocity of the Cadent by C B, is greater
than the velocity of the Deſcendent by C A?
SIMPL. I think ſo; becauſe in the ſame time that the Cadent
ſhall paſs all C B, the Deſcendent ſhall paſs in C A, a part leſs
than C B.
SALV. True; and thus it is proved, that the moveable moves
more ſwiftly by the perpendicular, than by the inclination. Now
conſider, if in this ſame Figure one may any way evince the
ther conceipt, and finde that the moveables were equally ſwift
by both the lines C A and C B.
SIMPL. I ſee no ſuch thing; nay rather it ſeems to contradict
what was ſaid before.
SALV. And what ſay you, Sagredus? I would not teach you
what you knew before, and that of which but juſt now you
duced me the definition.
SAGR. The definition I gave you, was, that moveables may
be called equally ſwift, when the ſpaces paſſed are proportional
to the times in which they paſſed; therefore to apply the
tion to the preſent caſe, it will be requiſite, that the time of
ſcent by C A, to the time of falling by C B, ſhould have the
ſame proportion that the line C A hath to the line C B; but I
underſtand not how that can be, for that the motion by C B is
ſwifter than by C A.
SALV. And yet you muſt of neceſſity know it. Tell me a little,
do not theſe motions go continually accelerating?
SAGR. They do; but more in the perpendicular than in the
inclination.
SALV. But this acceleration in the perpendicular, is it yet
withſtanding ſuch in compariſon of that of the inclined, that
two equal parts being taken in any place of the ſaid
lar and inclining lines, the motion in the parts of the
lar is alwaies more ſwift, than in the part of the inclination?
SAGR. I ſay not ſo: but I could take a ſpace in the
on, in which the velocity ſhall be far greater than in the like ſpace
taken in the perpendicular; and this ſhall be, if the ſpace in the
1perpendicular ſhould be taken near to the end C, and in the
clination, far from it.
SALV. You ſee then, that the Propoſition which ſaith, that
the motion by the perpendicular is more ſwift than by the
nation, holds not true univerſally, but onely of the motions,
which begin from the extremity, namely from the point of reſt:
without which reſtriction, the Propoſition would be ſo deficient,
that its very direct contrary might be true; namely, that the
tion in the inclining plane is ſwifter than in the perpendicular:
for it is certain, that in the ſaid inclination, we may take a ſpace
paſt by the moveable in leſs time, than the like ſpace paſt in the
perpendicular. Now becauſe the motion in the inclination is in
ſome places more, in ſome leſs, than in the perpendicular;
fore in ſome places of the inclination, the time of motion of the
moveable, ſhall have a greater proportion to the time of the motion
of the moveable, by ſome places of the perpendicular, than the
ſpace paſſed, to the ſpace paſſed: and in other places, the
portion of the time to the time, ſhall be leſs than that of the
ſpace to the ſpace. As for example: two moveables departing
from their quieſcence, namely, from the point C, one by the
pendicular C B, [in Fig. 4.] and the other by the inclination C A,
in the time that, in the perpendicular, the moveable ſhall have
paſt all C B, the other ſhall have paſt C T leſſer. And therefore
the time by C T, to the time by C B (which is equal) ſhall have
a greater proportion than the line C T to C B, being that the
ſame to the leſs, hath a greater proportion than to the greater.
And on the contrary, if in C A, prolonged as much as is
ſite, one ſhould take a part equal to C B, but paſt in a ſhorter
time; the time in the inclination ſhall have a leſs proportion to
the time in the perpendicular, than the ſpace to the ſpace. If
therefore in the inclination and perpendicular, we may ſuppoſe
ſuch ſpaces and velocities, that the proportion between the ſaid
ſpaces be greater and leſs than the proportion of the times; we
may eaſily grant, that there are alſo ſpaces, by which the times
of the motions retain the ſame proportion as the ſpaces.
SAGR. I am already freed from my greateſt doubt, and
ceive that to be not onely poſſible, but neceſſary, which I but
now thought a contradiction: but nevertheleſs I underſtand not
as yet, that this whereof we now are ſpeaking, is one of theſe
poſſible or neceſſary caſes; ſo as that it ſhould be true, that the
time of deſcent by C A, to the time of the fall by C B, hath the
ſame proportion that the line C A hath to C B; whence it may
without contradiction be affirmed, that the velocity by the
nation C A, and by the perpendicular C B, are equal.
SALV. Content your ſelf for this time, that I have removed
1your incredulity; but for the knowledge of this, expect it at
ſome other time, namely, when you ſhall ſee the matters
ning local motion demonſtrated by our Academick; at which
time you ſhall find it proved, that in the time that the one
ble falls all the ſpace C B, the other deſcendeth by C A as far
as the point T, in which falls the perpendicular drawn from the
point B: and to find where the ſame Cadent by the
cular would be when the other arriveth at the point A, draw from
A the perpendicular unto C A, continuing it, and C B unto the
interfection, and that ſhall be the point ſought. Whereby you
ſee how it is true, that the motion by C B is ſwifter than by the
inclination C A (ſuppoſing the term C for the beginning of the
motions compared) becauſe the line C B is greater than C T,
and the other from C unto the interſection of the perpendicular
drawn from A, unto the line C A, is greater than C A, and
therefore the motion by it is ſwifter than by C A But when we
compare the motion made by all C A, not with all the motion
made in the ſame time by the perpendicular continued, but with
that made in part of the time, by the ſole part C B, it hinders
not, that the motion by C A, continuing to deſcend beyond, may
arrive to A in ſuch a time as is in proportion to the other time,
as the line C A is to the line C B. Now returning to our firſt
purpoſe; which was to ſhew, that the grave moveable leaving
its quieſcence, paſſeth defcending by all the degrees of tardity,
precedent to any whatſoever degree of velocity that it aequireth,
re-aſſuming the ſame Figure which we uſed before, let us
ber that we did agree, that the Deſcendent by the inclination C
A, and the Cadent by the perpendicular C B, were found to have
acquired equal degrees of velocity in the terms B and A: now to
proceed, I ſuppoſe you will not ſcruple to grant, that upon
ther plane leſs ſteep than A C; as for example, A D [in Fig. 5.]
the motion of the deſcendent would be yet more ſlow than in the
plane A C. So that it is not any whit dubitable, but that there
may be planes ſo little elevated above the Horizon A B, that the
moveable, namely the ſame ball, in any the longeſt time may
reach the point A, which being to move by the plane A B, an
nite time would not ſuffice: and the motion is made always more
ſlowly, by how much the declination is leſs. It muſt be therefore
confeſt, that there may be a point taken upon the term B, ſo near
to the ſaid B, that drawing from thence to the point A a plane,
the ball would not paſs it in a whole year. It is requiſite next
for you to know, that the impetus, namely the degree of
city the ball is found to have acquired when it arriveth at the
point A, is ſuch, that ſhould it continue to move with this ſelf-ſame
degree uniformly, that is to ſay, without accelerating or retarding;
1in as much more time as it was in coming by the inclining plane, it
would paſs double the ſpace of the plane inclined: namely (for
example) if the ball had paſt the plane D A in an hour,
tinuing to move uniformly with that degree of velocity which it
is found to have in its arriving at the term A, it ſhall paſs in an
hour a ſpace double the length D A; and becauſe (as we have
ſaid) the degrees of velocity acquired in the points B and A, by
the moveables that depart from any point taken in the
lar C B, and that deſcend, the one by the inclined plane, the
ther by the ſaid perpendicular, are always equal: therefore the
cadent by the perpendicular may depart from a term ſo near to B,
that the degree of velocity acquired in B, would not ſuffice (ſtill
maintaining the ſame) to conduct the moveable by a ſpace
ble the length of the plane inclined in a year, nor in ten, no nor
in a hundred. We may therefore conclude, that if it be true,
that according to the ordinary courſe of nature a moveable, all
external and accidental impediments removed, moves upon an
clining plane with greater and greater tardity, according as the
inclination ſhall be leſs; ſo that in the end the tardity comes to be
infinite, which is, when the inclination concludeth in, and joyneth
to the horizontal plane; and if it be true likewiſe, that the
gree of velocity acquired in ſome point of the inclined plane, is
equal to that degree of velocity which is found to be in the
able that deſcends by the perpendicular, in the point cut by a
parallel to the Horizon, which paſſeth by that point of the
ning plane; it muſt of neceſſity be granted, that the cadent
parting from reſt, paſſeth thorow all the infinite degrees of
dity, and that conſequently, to acquire a determinate degree of
velocity, it is neceſſary that it move firſt by right lines,
ing by a ſhort or long ſpace, according as the velocity to be
red, ought to be either leſs or greater, and according as the plane
on which it deſcendeth is more or leſs inclined; ſo that a plane
may be given with ſo ſmall inclination, that to acquire in it the
aſſigned degree of velocity, it muſt firſt move in a very great ſpace,
and take a very long time; whereupon in the horizontal plane, any
how little ſoever velocity, would never be naturally acquired,
ſince that the moveable in this caſe will never move: but the

motion by the horizontal line, which is neither declined or
ned, is a circular motion about the centre: therefore the
lar motion is never acquired naturally, without the right motion
precede it; but being once acquired, it will continue perpetually
with uniform velocity. I could with other diſcourſes evince and
demonſtrate the ſame truth, but I will not by ſo great a
fion interrupt our principal argument: but rather will return to
it upon ſome other occaſion; eſpecially ſince we now aſſumed the
1ſame, not to ſerve for a neceſſary demonſtration, but to adorn a
Platonick Conceit; to which I will add another particular
vation of our Academick, which hath in it ſomething of
ble. Let us ſuppoſe amongſt the decrees of the divine Architect,
a purpoſe of creating in the World theſe Globes, which we
hold continually moving round, and of aſſigning the centre of
their converſions; and that in it he had placed the Sun immoveable,
and had afterwards made all the ſaid Globes in the ſame place,
and with the intended inclinations of moving towards the Centre,
till they had acquired thoſe degrees of velocity, which at firſt
med good to the ſame Divine Minde; the which being acquired,
we laſtly ſuppoſe that they were turned round, each in his Sphere
retaining the ſaid acquired velocity: it is now demanded, in
what altitude and diſtance from the Sun the place was where the
ſaid Orbs were primarily created; and whether it be poſſible that
they might all be created in the ſame place? To make this
ſtigation, we muſt take from the moſt skilfull Aſtronomers the
magnitude of the Spheres in which the Planets revolve, and
wiſe the time of their revolutions: from which two cognitions is
gathered how much (for example) Jupiter is ſwifter than
turne; and being found (as indeed it is) that Jupiter moves more
ſwiftly, it is requiſite, that departing from the ſame altitude,
piter be deſcended more than Saturne, as we really know it is, its
Orbe being inferiour to that of Saturne. But by proceeding
wards, from the proportions of the two velocities of Jupiter and
Saturne, and from the diſtance between their Orbs, and from the
proportion of acceleration of natural motion, one may finde in
what altitude and diſtance from the centre of their revolutions,

was the place from whence they firſt departed. This found out,
and agreed upon, it is to be ſought, whether Mars deſcending
from thence to his Orb, the magnitude of the Orb, and the
locity of the motion, agree with that which is found by
tion; and let the like be done of the Eartb, of Venus, and of
Mercury; the greatneſs of which Spheres, and the velocity of
their motions, agree ſo nearly to what computation gives, that it
is very admirable.
The circular
tion is never
quired naturally,
without right
tion precede it.
Circular motion
perpetually
form.
The magnitude of
the Orbs, and the
velocity of the
tion of the Planets,
anſwer
ably, as if
ed from the ſame
place.
SAGR. I have hearkened to this conceit with extreme delight;
and, but that I believe the making of theſe calculations truly
would be a long and painfull task, and perhaps too hard for me
to comprehend, I would make a trial of them.
SALV. The operation indeed is long and difficult; nor could
I be certain to finde it ſo readily; therefore we ſhall refer it to
other time, and for the preſent we will return to our firſt
ſal, going on there where we made digreſſion; which, if I well
remember, was about the proving the motion by a right line of no
1uſe, in the ordinate parts of the World; and we did proceed to
ſay, that it was not ſo in circular motions, of which that which is
made by the moveable in it ſelf, ſtill retains it in the ſame place,

and that which carrieth the moveable by the circumference of a
circle about its fixed centre, neither puts it ſelf, nor thoſe about it
in diſorder; for that ſuch a motion primarily is finite and terminate
(though not yet finiſhed and determined) but there is no point

in the circumference, that is not the firſt and laſt term in the
culation; and continuing it in the circumference aſſigned it, it
leaveth all the reſt, within and without that, free for the uſe of
others, without ever impeding or diſordering them. This being
a motion that makes the moveable continually leave, and

tinually arrive at the end; it alone therefore can primarily be
niform; for that acceleration of motion is made in the moveable,
when it goeth towards the term, to which it hath inclination;
and the retardation happens by the repugnance that it hath to
leave and part from the ſame term; and becauſe in circular
tion, the moveable continually leaves the natural term, and
tinually moveth towards the ſame, therefore, in it, the
nance and inclination are always of equal force: from which
quality reſults a velocity, neither retarded nor accelerated, i. e. an
uniformity in motion. From this conformity, and from the being

terminate, may follow the perpetual continuation by ſucceſſively
reiterating the circulations; which in an undeterminated line,
and in a motion continually retarded or accelerated, cannot

turally be. I ſay, naturally; becauſe the right motion which is
retarded, is the violent, which cannot be perpetual; and the
celerate arriveth neceſſarily at the term, if one there be; and if
there be none, it cannot be moved to it, becauſe nature moves
not whether it is impoſſible to attain. I conclude therefore, that
the circular motion can onely naturally conſiſt with natural
dies, parts of the univerſe, and conſtituted in an excellent
ſure; and that the right, at the moſt that can be ſaid for it, is

aſſigned by nature to its bodies, and their parts, at ſuch time as
they ſhall be out of their proper places, conſtituted in a depraved
diſpoſition, and for that cauſe needing to be redured by the
eſt way to their natural ſtate. Hence, me thinks, it may
nally be concluded, that for maintenance of perfect order among ſt
the parts of the World, it is neceſſary to ſay, that moveables are
moveable onely circularly; and if there be any that move not

circularly, theſe of neceſſity are immoveable: there being
thing but reſt and circular motion apt to the conſervation of
der. And I do not a little wonder with my ſelf, that Ariſtotle,
who held that the Terreſtrial globe was placed in the centre of
the World, and there remained immoveable, ſhould not ſay, that
1of natural bodies ſome are moveable by nature, and others
veable; eſpecially having before defined Nature, to be the
ciple of Motion and Reſt.
Finite and
nate circular
tions diſorder not
the parts of the
World.
In the circular
tion, every point in
the circumference
is the begining and
end.
Circular motion
onely is uniform.
Circular motion
may be continued
perpetually.
Right motion
not naturally be
perpetual.
Right motion
ſigned to natural
bodies, to reduce
them to perfect
der, when removed
from their places.
Reſt onely, and
circular motion are
apt to conſerve
der.
SIMPL. Ariſtotle, though of a very perſpicacious wit, would
not ſtrain it further than needed: holding in all his

tations, that ſenſible experiments were to be preferred before
any reaſons founded upon ſtrength of wit, and ſaid thoſe which
ſhould deny the teſtimony of ſenſe deſerved to be puniſhed with

the loſs of that ſenſe; now who is ſo blind, that ſees not the
parts of the Earth and Water to move, as being grave,
ly downwards, namely, towards the centre of the Univerſe,
ſigned by nature her ſelf for the end and term of right motion
deorſùm; and doth not likewiſe ſee the Fire and Air to move
right upwards towards the Concave of the Lunar Orb, as to the
natural end of motion ſurſùm? And this being ſo manifeſtly ſeen,
and we being certain, that eadem est ratio totius & partium, why
may we not aſſert it for a true and manifeſt propoſition, that the
natural motion of the Earth is the right motion ad medium, and
that of the Fire, the right à medio?
Senſible
ments are to be
ferred before
mane argument
tions.
He who denies
ſenſe, deſerves to
be deprived of it.
Senſe ſheweth that
things grave move
to the medium, and
the light to the
concave.
SALV. The moſt that you can pretend from this your
courſe, were it granted to be true, is that, like as the parts of the
Earth removed from the whole, namely, from the place where
they naturally reſt, that is in ſhort reduced to a depraved and
ordered diſpoſure, return to their place ſpontaneouſly, and
fore naturally in a right motion, (it being granted, that eadem
ſit ratio totius & partium) ſo it may be inferred, that the
Terreſtrial Globe removed violently from the place aſſigned

it by nature, it would return by a right line. This, as I have
ſaid, is the moſt that can be granted you, and that onely for want
of examination; but he that ſhall with exactneſs reviſe theſe
things, will firſt deny, that the parts of the Earth, in returning to
its whole, move in a right line, and not by a circular or mixt; and
really you would have enough to do to demonſtrate the
ry, as you ſhall plainly ſee in the anſwers to the particular reaſons
and experiments alledged by Ptolomey and Ariſtotle. Secondly,
If another ſhould ſay that the parts of the Earth, go not in their
motion towards the Centre of the World, but to unite with its
Whole, and that for that reaſon they naturally incline towards the
centre of the Terreſtrial Globe, by which inclination they
ſpire to form and preſerve it, what other All, or what other Centre
would you find for the World, to which the whole Terrene

Globe, being thence removed, would ſeek to return, that ſo the
reaſon of the Whole might be like to that of its parts? It may be
added, That neither Ariſtotle, nor you can ever prove, that the
Earth de facto is in the centre of the Univerſe; but if any Centre
1
may be aſligned to the Univerſe, we ſhall rather find the Sun
placed in it, as by the ſequel you ſhall underſtand.
It is queſtionable
whether deſcending
weights move in a
right line.
The Earth
cal by the
ration of its parts
to its Centre.
The Sun more
bably in the centre
of the Vniverſe,
than the Earth.
Now, like as from the conſentaneous conſpiration of all the
parts of the Earth to form its whole, doth follow, that they with

equal inclination concurr thither from all parts; and to unite
themſelves as much as is poſſible together, they there ſphelically
adapt themſelves; why may we not believe that the Sun, Moon,
and other mundane Bodies, be alſo of a round figure, not by
ther than a concordant inſtinct, and natural concourſe of all the
parts compoſing them? Of which, if any, at any time, by any
violence were ſeparated from the whole, is it not reaſonable to
think, that they would ſpontaneouſly and by natural inſtinct
turn? and in this manner to infer, that the right motion agreeth
with all mundane bodies alike.
Natural
tion of the parts of
all the globes of
the World to go to
their centre.
SIMPL. Certainly, if you in this manner deny not onely the
Principles of Sciences, but manifeſt Experience, and the Senſes
themſelves, you can never be convinced or removed from any
pinion which you once conceit, therefore I will chooſe rather to
be ſilent (for, contra negantes principia non eſt diſputandum)
than contend with you. And inſiſting on the things alledged by
you even now (ſince you queſtion ſo much as whether grave
ables have a right motion or no) how can you ever rationally

ny, that the parts of the Earth; or, if you will, that ponderous
matters deſcend towards the Centre, with a right motion;
as, if from a very high Tower, whoſe walls are vcry upright and
perpendicular, you let them fall, they ſhall deſcend gliding and
ſliding by the Tower to the Earth, exactly in that very place
where a plummet would fall, being hanged by a line faſtned above,
juſt there, whence the ſaid weights were let fall? is not this a
more than evident argument of the motions being right, and

wards the Centre? In the ſecond place you call in doubt,
ther the parts of the Earth are moved, as Ariſtotle affirms,
wards the Centre of the World; as if he had not rationally
monſtrated it by contrary motions, whilſt he thus argueth; The
motion of heavie bodies is contrary to that of the light: but the
motion of the light is manifeſt to be directly upwards, namely,
towards the circumference of the World, therefore the motion of
the heavie is directly towards the Centre of the World: and it

happens per accidens, that it be towards the centre of the Earth,
for that this ſtriveth to be united to that. The ſeeking in the
next place, what a part of the Globe of the Sun or Moon would
do, were it ſeparated from its whole, is vanity; becauſe that

by that is ſought, which would be the conſequence of an
bility; in regard that, as Ariſtotle alſo demonſtrates, the cœleſtial
bodies are impaſſible, impenetrable, and infrangible; ſo that ſuch
1a caſe can never happen: and though it ſhould, and that the

parated part ſhould return to its whole, it would not return as
grave or light, for that the ſame Ariſtotle proveth, that the
leſtial Bodies are neither heavie nor light.
The right motion
of grave bodies
manifeſt to ſenſe.
Arguments of
riſtotle, to prove
that grave bodies
move with an
clination to arrive
at the centre of the
Vniverſe.
Heavie bodies
move towards the
centre of the Earth
per accidens.
To ſeek what
would follow upon
an impoſſibility, is
folly.
Cœleſtial bodies
neither heavie nor
light, according to
Ariſtotle.
SALV. With what reaſon I doubt, whether grave bodies move
by a right and perpendicular line, you ſhall hear, as I ſaid
fore, when I ſhall examine this particular argument. Touching
the ſecond point, I wonder that you ſhould need to diſcover the
Paralogiſm of Ariſtotle, being of it ſelf ſo manifeſt; and that
you perceive not, that Ariſtotle ſuppoſeth that which is in
on: therefore take notice.
SIMPL. Pray Salviatus ſpeak with more reſpect of Ariſtotle:
for who can you ever perſwade, that he who was the firſt, only,
and admirable explainer of the Syllogiſtick forms of demonſtration,

of Elenchs, of the manner of diſcovering Sophiſms, Paralogiſms, and
in ſhort, of all the parts of Logick, ſhould afterwards ſo notoriouſly
equivocate in impoſing that for known, which is in queſtion? It
would be better, my Maſters, firſt perfectly to underſtand him,
and then to try, if you have a minde, to oppoſe him.
Ariſtotle cannot
quivocate, being
the inventer of
gick.
SALV. Simplicius, we are here familiarly diſcourſing among
our ſelves, to inveſtigate ſome truth; I ſhall not be diſpleaſed
that you diſcover my errors; and if I do not follow the mind of
Ariſtotle, freely reprehend me, and I ſhall take it in good part.
Onely give me leave to expound my doubts, and to reply
thing to your laſt words, telling you, that Logick, as it is well
underſtood, is the Organe with which we philoſophate; but as it
may be poſſible, that an Artiſt may be excellent in making
gans, but unlearned in playing on them, thus he might be a great
Logician, but unexpert in making uſe of Logick; like as we have
many that theorically underſtand the whole Art of Poetry, and
yet are unfortunate in compoſing but meer four Verſes; others

enjoy all the precepts of Vinci^{*}, and yet know not how to paint
a Stoole. The playing on the Organs is not taught by them who
know how to make Organs, but by him that knows how to play
on them: Poetry is learnt by continual reading of Poets:
ing is learnt by continual painting and deſigning: Demonſtration
from the reading of Books full of demonſtrations, which are the
Mathematical onely, and not the Logical. Now returning to our
purpoſe, I ſay, that that which Ariſtotle ſeeth of the motion of
light bodies, is the departing of the Fire from any part of the
Superficies of the Terreſtrial Globe, and directly retreating from
it, mounting upwards; and this indeed is to move towards a
circumference greater than that of the Earth; yea, the ſame
riſtotle makes it to move to the concave of the Moon, but that
this circumference is that of the World, or concentrick to it, ſo
1that to move towards this, is a moving towards that of the World,
that he cannot affirm, unleſs he ſuppoſeth, That the Centre of the

Earth, from which we ſee theſe light aſcendent bodies to depart,
be the ſame with the Centre of the World; which is as much as
to ſay, that the terreſtrial Globe is conſtituted in the midſt of the
World: which is yet that of which we were in doubt, and which
Aristotle intended to prove. And do you ſay that this is not a

manifeſt Paralogiſm?
* A famous Italian
Painter.
Paralogiſm of
riſtotle, in proving
the Earth to be in
the Centre of the
World.
The Paralogiſme
of Ariſtotle another
way diſcovered.
SAGR. This Argument of Ariſtotle appeared to me deficient
alſo, and non-concludent for another reſpect; though it were
granted, that that Circumference, to which the Fire directly
veth, be that which includeth the World: for that in a circle,
not onely the centre, but any other point being taken, every
able which departing thence, ſhall move in a right line, and
wards any whatſoever part, ſhall without any doubt go towards
the circumference, and continuing the motion, ſhall alſo arrive
thither; ſo that we may truly ſay, that it moveth towards the
circumference: but yet it doth not follow, that that which
veth by the ſame line with a contrary motion, would go towards
the centre, unleſs when the point taken were the centre it ſelf,
or that the motion were made by that onely line, which produced
from the point aſſigned, paſſeth thorow the centre. So that to
ſay, that Fire moving in a right line, goeth towards the
rence of the World, therefore the parts of the Earth which by
the ſame lines move with a contrary motion, go towards the
tre of the World, concludeth not, unleſs then when it is
ſuppoſed, that the lines of the Fire prolonged paſs by the centre
of the World; and becauſe we know certainly of them, that they
paſs by the centre of the Terreſtrial Globe (being
lar to its ſuperficies, and not inclined) therefore to conclude, it
muſt be ſuppoſed, that the centre of the Earth is the ſame with
the centre of the World; or at leaſt, that the parts of the Fire
and Earth deſcend not, ſave onely by one ſole line which paſſeth
by the centre of the World. Which nevertheleſs is falſe, and
pugnant to experience, which ſheweth us, that the parts of
Fire, not by one line onely, but by infinite, produced from the
centre of the Earth towards all the parts of the World, aſcend
always by lines perpendicular to the Superficies of the
al Globe.
SALV. You do very ingeniouſly lead Ariſtotle to the ſame
convenience, Sagredus, ſhewing his manifeſt equivoke; but
withal you add another inconſiſtency. We ſee the Earth to be
ſpherical, and therefore are certain that it hath its centre, to which
we ſee all its parts are moved; for ſo we muſt ſay, whilſt their
motions are all perpendicular to the Superficies of the Earth; we
1mean, that as they move to the centre of the Earth, they move to
their Whole, and to their Univerſal Mother: and we are ſtill
ther ſo free, that we will ſuffer our ſelves to be perſwaded, that

their natural inſtinct is, not to go towards the centre of the Earth,
but towards that of the Univerſe; which we know not where to
find, or whether it be or no; and were it granted to be, it is but
an imaginary point, and a nothing without any quality. As to
what Simplicius ſaid laſt, that the contending whether the parts
of the Sun, Moon, or other cœleſtial Body, ſeparated from their
Whole, ſhould naturally return to it, is a vanity, for that the caſe
is impoſſible; it being clear by the Demonſtrations of Ariſtotle,
that the cœleſtial Bodies are impaſſible, impenetrable,

ble, &c. I anſwer, that none of the conditions, whereby
tle diſtinguiſheth the Cœleſtial Bodies from Elementary, hath
ther foundation than what he deduceth from the diverſity of the
natural motion of thoſe and theſe; inſomuch that it being
ed, that the circular motion is peculiar to Cœleſtial Bodies, and
affirmed, that it is agreeable to all Bodies naturally moveable, it
is behoofull upon neceſſary conſequence to ſay, either that the
attributes of generable, or ingenerable, alterable, or unalterable,
partable, or unpartable, &c. equally and commonly agree with
all worldly bodies, namely, as well to the Cœleſtial as to the
lementary; or that Ariſtotle hath badly and erroneouſly
ced thoſe from the circular motion, which he hath aſſigned to
leſtial Bodies.
Grave bodies may
more rationally be
affirmed to tend to
the Centre of the
Earth, than of the
Vniverſe.
The conditions and
attributes which
differ the cœleſtial
bodies from
mentary, depend on
the motions
ed them by Ariſt.
SIMPL. This manner of argumentation tends to the
on of all Natural Philoſophy, and to the diſorder and ſubverſion
of Heaven and Earth, and the whole Univerſe; but I believe the
Fundamentals of the Peripateticks are ſuch, that we need not
fear that new Sciences can be erected upon their ruines.
SALV. Take no thought in this place for Heaven or the Earth,
neither fear their ſubverſion, or the ruine of Philoſophy. As to
Heaven, your fears are vain for that which you your ſelf hold
unalterable and impaſſible; as for the Earth, we ſtrive to enoble
and perfect it, whilſt we make it like to the Cœleſtial Bodies,
and as it were place it in Heaven, whence your Philoſophers have
exiled it. Philoſophy it ſelf cannot but receive benefit from our

Diſputes, for if our conceptions prove true, new Diſcoveries will
be made; if falſe, the firſt Doctrine will be more confirmed.
Rather beſtow your care upon ſome Philoſophers, and help and
defend them; for as to the Science it ſelf, it cannot but improve.
And that we may return to our purpoſe, be pleaſed freely to
duce what preſents it ſelf to you in confirmation of that great
ference which Ariſtotle puts between the Cœleſtial Bodies, and
the Elementary parts of the World, in making thoſe ingenerable,
1incorruptible, unalterable, &c. and this corruptible, alterable, &c.
The diſputes and
contradictions of
Philoſophers may
conduce to the
benefit of
phy.
SIMPL. I ſee not yet any need that Ariſtotle hath of help,
ſtanding as he doth ſtoutly and ſtrongly on his feet; yea not
ing yet aſſaulted, much leſs foiled by you. And what ward will
you chooſe in this combate for this firſt blow? Aristotle writeth,

that whatever is generated, is made out of a contrary in ſome
ſubject, and likewiſe is corrupted in ſome certain ſubject from a

contrary into a contrary; ſo that (obſerve) corruption and
neration is never but onely in contraries; If therefore to a
leſtial Body no contrary can be aſſigned, for that to the circular

motion no other motion is contrary, then Nature hath done very
well to make that exempt from contraries, which was to be
generable and incorruptible, This fundamental firſt confirmed,
it immediately followeth of conſequence, that it is
ble, inalterable, impaſſible, and finally eternal, and a

tionate habitation to the immortal Deities, conformable to the
opinion even of all men that have any conceit of the Gods. He

afterwards confirmeth the ſame by ſenſe; in regard, that in all
times paſt, according to memory or tradition, we ſee nothing
moved, according to the whole outward Heaven, nor any of its

proper parts. Next, as to the circular motion, that no other is
contrary to it, Aristotle proveth many ways; but without
ting them all, it is ſufficiently demonſtrated, ſince fimple motions
are but three, to the medium, from the medium, and about the
medium, of which the two right, ſurſum and deorſum, are
feſtly contrary; and becauſe one onely hath onely one for
trary, therefore there reſts no other motion which may be
ry to the circular. You ſee the ſubtle and moſt concluding
courſe of Ariſtotle, whereby he proveth the incorruptibility of
Heaven.
Ariſtotles diſcourſe
to prove the
ruptibility of
ven.
Generation &
ruption is onely
mongſt contraries,
according to Ariſt.
To the circular
motion no other
motion is contrary.
Heaven an
tation for the
ortal Gods.
Immutability of
Heaven evident to
ſexſe.
He proveth that
the circular motion
hath no contrary.
SALV. This is nothing more, ſave the pure progreſs of
tle, by me hinted before; wherein, beſides that I affirm, that the
motion which you attribute to the Cœleſtial Bodies agreeth alſo
to the Earth, its illation proves nothing. I tell you therefore,
that that circular motion which you aſſign to Cœleſtial Bodies,
ſuiteth alſo to the Earth, from which, ſuppoſing that the reſt of
your diſcourſe were concludent, will follow one of theſe three
things, as I told you a little before, and ſhall repeat; namely,
either that the Earth it ſelf is alſo ingenerable, and incorruptible,
as the Cœleſtial bodies; or that the Cœleſtial bodies are, like as
the Elementary generable, alterable &c. or that this difference of
motion hath nothing to do with Generation and Corruption.
The diſcourſe of Ariſtotle, and yours alſo contain many
tions not to be lightly admitted, and the better to examine them,
it will be convenient to reduce them to the moſt abſtracted and
1diſtinct that can be poſſible; and excuſe me Sagredus, if haply
with ſome tediouſneſs you hear me oft repeat the ſame things,
and fancie that you ſee me reaſſume my argument in the
lick circle of Diſputations. You ſay Generation and
on are onely made where there are contraries; contraries
are onely amongſt ſimple natural bodies, moveable with contrary
motions; contrary motions are onely thoſe which are made by
a right line between contrary terms; and theſe are onely two,
that is to ſay, from the medium, and towards the medium; and
ſuch motions belong to no other natural bodies, but to the Earth,
the Fire, and the other two Elements: therefore Generation
and Corruption is onely amongſt the Elements. And becauſe
the third ſimple motion, namely, the circular about the medium,
hath no contrary, (for that the other two are contraries, and one
onely, hath but onely one contrary) therefore that natural body
with which ſuch motion agreeth, wants a contrary; and having
no contrary is ingenerable and incorruptible, &c. Becauſe where
there is no contrariety, there is no generation or corruption, &c.
But ſuch motion agreeth onely with the Cœleſtial bodies;

fore onely theſe are ingenerable, incorruptible, &c. And to
begin, I think it a more eaſie thing, and ſooner done to reſolve,
whether the Earth (a moſt vaſt Body, and for its vicinity to us,
moſt tractable) moveth with a ſpeedy motion, ſuch as its
lution about its own axis in twenty four hours would be, than it
is to underſtand and reſolve, whether Generation and Corruption
ariſeth from contrariety, or elſe whether there be ſuch things as
generation, corruption and contrariety in nature. And if you,
Simplicius, can tell me what method Nature obſerves in working,
when ſhe in a very ſhort time begets an infinite number of flies
from a little vapour of the Muſt of wine, and can ſhew me which
are there the contraries you ſpeak of, what it is that corrupteth,
and how; I ſhould think you would do more than I can; for I
profeſs I cannot comprehend theſe things. Beſides, I would
ry gladly underſtand how, and why theſe corruptive contraries are
ſo favourable to Daws, and ſo cruel to Doves; ſo indulgent to
Stags, and ſo haſty to Horſes, that they do grant to them many
more years of life, that is, of incorruptibility, than weeks to theſe.
Peaches and Olives are planted in the ſame ſoil, expoſed to the
ſame heat and cold, to the ſame wind and rains, and, in a word,
to the ſame contrarieties; and yet thoſe decay in a ſhort time,
and theſe live many hundred years. Furthermore, I never was
thorowly ſatisfied about this ſubſtantial tranſmutation (ſtill
ing within pure natural bounds) whereby a matter becometh ſo
transform'd, that it ſhould be neceſſarily ſaid to be deſtroy'd, ſo
that nothing remaineth of its firſt being, and that another body
1
quite differing there-from ſhould be thence produced; and if I
fancy to my ſelf a body under one aſpect, and by and by under
another very different, I cannot think it impoſſible but that it may
happen by a ſimple tranſpoſition of parts, without corrupting or
ingendring any thing a-new; for we ſee ſuch kinds of
phoſes dayly: ſo that to return to my purpoſe, I anſwer you,
that inaſmuch as you go about to perſwade me that the Earth can
not move circularly by way of corruptibility and generability,
you have undertook a much harder task than I, that with
ments more difficult indeed, but no leſs concluding, will prove
the contrary.
Its eaſier to prove
the Earth to move,
than that
on is made by
traries.
Bare tranſpoſition
of parts may
ſent bodies under
diverſe asp cts.
SAGR. Pardon me, Salviatus, if I interrupt your diſcourſe,
which, as it delights me much, for that I alſo am gravel'd with
the ſame doubts; ſo I fear that you can never conclude the ſame,
without altogether digreſſing from your chief deſign: therefore
if it be permitted to proceed in our firſt argument, I ſhould think
that it were convenient to remit this queſtion of generation and
corruption to another diſtinct and ſingle conference; as alſo, if
it ſhall pleaſe you and Simplicius, we may do by other particular
queſtions which may fall in the way of our diſcourſe; which I
will keep in my mind to propoſe, and exactly diſcuſs them ſome
other time. Now as for the preſent, ſince you ſay, that if
ſtotle deny circular motion to the Earth in common with other
bodies Cœleſtial, it chence will follow, that the ſame which
falleth the Earth, as to its being generable, alterable, &c. will
hold alſo of Heaven, let us enquire no further if there be ſuch
things in nature, as generation and corruption, or not; but let
us return to enquire what the Globe of the Earth doth.
SIMPL. I cannot ſuffer my ears to hear it queſtion'd, whether
generation and corruption be in rerum naturà, it being a thing
which we have continually before our eyes, and whereof Ariſtotle

hath written two whole Books. But if you go about to deny the
Principles of Sciences, and queſtion things moſt manifeſt, who
knows not, but that you may prove what you will, and maintain
any Paradox? And if you do not dayly ſee herbs, plants,
mals to generate and corrupt, what is it that you do ſee? Alſo,
do you not continually behold contrarieties contend together,
and the Earth change into Water, the Water turn to Air, the
Air into Fire, and again the Air to condenſe into Clouds, Rains,
Hails and Storms?
By denying
ciples in the
ces, any Paradox
may be
ed.
SAGR. Yes, we ſee theſe things indeed, and therefore will
grant you the diſcourſe of Ariſtotle, as to this part of generation
and corruption made by contraries; but if I ſhall conclude by
virtue of the ſame propoſitions which are granted to Ariſtotle,
that the Cœleſtial bodies themſelves are alſo generable and
1ruptible, aſwell as the Elementary, what will you ſay then?
SIMPL. I will ſay you have done that which is impoſſible to
be done.
SAGR. Go to; tell me, Simplicius, are not theſe affections
contrary to one another?
SIMPL. Which?
SAGR. Why theſe; Alterable, unalterable; paſſible, ^{*}

ſible; generable, ingenerable; corruptible, incorruptible?
* Or, Impatible.
SIMPL. They are moſt contrary.
SAGR. Well then, if this be true, and it be alſo granted,
that Cœleſtial Bodies are ingenerable and incorruptible; I prove
that of neceſſity Cœleſtial Bodies muſt be generable and
ptible.
SIMPL. This muſt needs be a Sophiſm.
SAGR. Hear my Argument, and then cenſure and reſolve it.

Cœleſtial Bodies, for that they are ingenerable and incorruptible,
have in Nature their contraries, which are thoſe Bodies that be
generable and corruptible; but where there is contrariety, there
is alſo generation and corruption; therefore Cœleſtial Bodies are
generable and corruptible.
Cœlestial Bodies
are generable and
corruptible,
cauſe they are
generable and
corruptible.
SIMPL. Did I not ſay it could be no other than a Sophiſm?
This is one of thoſe forked Arguments called Soritæ: like that

of the Cretan, who ſaid that all Cretans were lyars; but he as
being a Cretan, had told a lye, in ſaying that the Cretans were
ars; it followed therefore, that the Cretans were no lyars, and
conſequently that he, as being a Cretan, had ſpoke truth: And
yet in ſaying the Cretans were lyars, he had ſaid true, and
prehending himſelf as a Cretan, he muſt conſequently be a lyar.
And thus in theſe kinds of Sophiſms a man may dwell to eternity,
and never come to any concluſion.
The forked
giſm cal'd Ξωρίτης.
SAGR. You have hitherto cenſured it, it remaineth now that
you anſwer it, ſhewing the fallacie.
SIMPL. As to the reſolving of it, and finding out its fallacie,
do you not in the firſt place ſee a manifeſt contradiction in it?
Cœleſtial Bodies are ingenerable and incorruptible; Ergo,
ſtial Bodies are generable and corruptible. And again, the

trariety is not betwixt the Cœleſtial Bodies, but betwixt the
lements, which have the contrariety of the Motions, ſurſùm and
deorſùm, and of levity and gravity; But the Heavens which move
circularly, to which motion no other motion is contrary, want
contrariety, and therefore they are incorruptible.
Amongſt Cœleſtial
Bodies there is no
contrariety.
SAGR. Fair and ſoftly, Simplicius; this contrariety whereby
you ſay ſome ſimple Bodies become corruptible, reſides it in the
ſame Body which is corrupted, or elſe hath it relation to ſome
other? I ſay, for example, the humidity by which a piece of Earth
1is corrupted, reſides it in the ſame Earth or in ſome other bodie,
which muſt either be the Air or Water? I believe you will grant,
that like as the Motions upwards and downwards, and gravity
and levity, which you make the firſt contraries, cannot be in the
ſame Subject, ſo neither can moiſt and dry, hot and cold: you
muſt therefore conſequently acknowledg that when a bodie

rupteth, it is occaſioned by ſome quality reſiding in another
trary to its own: therefore to make the Cœleſtial Body become
corruptible, it ſufficeth that there are in Nature, bodies that have
a contrariety to that Cœleſtial body; and ſuch are the Elements,
if it be true that corruptibility be contrary to incorruptibility.
Contraries which
are the cauſes of
corruption, reſide
not in the ſame
dy that corrupteth.
SIMPL. This ſufficeth not, Sir; The Elements alter and
rupt, becauſe they are intermixed, and are joyn'd to one another,

and ſo may exerciſe their contrariety; but Cœleſtial bodies are
ſeparated from the Elements, by which they are not ſo much as
toucht, though indeed they have an influence upon the Elements.
It is requiſite, if you will prove generation and corruption in
leſtial bodies, that you ſhew, that there reſides contrarieties
tween them.
Cœleſtial Bodies
touch, but are not
touched by the
lements.
SAGR. See how I will find thoſe contrarieties between them.
The firſt fountain from whence you derive the contrariety of the
Elements, is the contrariety of their motions upwards and
wards: it therefore is neceſſary that thoſe Principles be in like

manner contraries to each other, upon which thoſe motions
pend. and becauſe that is moveable upwards by lightneſs,
and this downwards by gravitv, it is neceſſary that lightneſs and
gravity are contrary to each other: no leſs are we to believe thoſe
other Principles to be contraries, which are the cauſes that this is
heavy, and that light: but by your own confeſſion, levity and
gravity follow as conſequents of rarity and denſity; therefore

rarity and denſity ſhall be contraries: the which conditions or
affections are ſo amply found in Cœleſtial bodies, that you
ſteem the ſtars to be onely more denſe parts of their Heaven:
and if this be ſo, it followeth that the denſity of the ſtars exceeds
that of the reſt of Heaven, by almoſt infinite degrees:
which is manifeſt, in that Heaven is infinitely tranſparent, and
the ſtars extremely opacous; and for that there are there above
no other qualities, but more and leſs denſity and rarity, which
may be cauſes of the greater or leſs tranſparency. There being
then ſuch contrariety between the Cœleftial bodies, it is neceſſary
that they alſo be generable and corruptible, in the ſame manner
as the Elementary bodies are; or elſe that contrariety is not the

cauſe of corruptibility, &c.
Gravity & levity,
varity and denſity,
are contrary
lities.
The ſtars infinitely
ſurpaſs the
ſtance of the reſt of
Heaven in denſity.
Rarity & denſity
in Cœleſtial bodies,
is different from
the rarity &
ſity of the elements.
SIMPL. There is no neceſſity either of one or the other, for
that denſity and rarity in Cœleſtial bodies, are not contraries to
1each other, as in Elementary bodies; for that they depend not
on the primary qualities, cold and heat, which are contraries; but
on the more or leſs matter in proportion to quantity: now much
and little, ſpeak onely a relative oppoſition, that is, the leaſt of
oppoſitions, and which hath nothing to do with generation and
corruption.
SAGR. Therefore affirming, that denſity and rarity, which
mongſt the Elements ſhould be the cauſe of gravity and levity,
which may be the cauſes of contrary motions ſurſùm and
ſùm, on which, again, dependeth the contrarieties for generation
and corruption; it ſufficeth not that they be thoſe denſneſſes and
rareneſſes which under the ſame quantity, or (if you will) maſs
contain much or little matter, but it is neceſſary that they be
neſſes and rareneſſes cauſed by the primary qualities, hot and
cold, otherwiſe they would operate nothing at all: but if this be
ſo, Ariſtotle hath deceived us, for that he ſhould have told it us at

firſt, and ſo have left written that thoſe ſimple bodies are
rable and corruptible, that are moveable with ſimple motions
upwards and downwards, dependent on levity and gravity,
ſed by rarity and denſity, made by much or little matter, by
reaſon of heat and cold; and not to have ſtaid at the ſimple
tion ſurſùm and deorſùm: for I aſſure you that to the making
of bodies heavy or light, whereby they come to be moved with
contrary motions, any kind of denſity and rarity ſufficeth,
ther it proceed from heat and cold, or what elſe you pleaſe; for
heat and cold have nothing to do in this affair: and you ſhall
upon experiment find, that a red hot iron, which you muſt grant
to have heat, weigheth as much, and moves in the ſame manner
as when it is cold. But to overpaſs this alſo, how know you but
that Cœleſtial rarity and denſity depend on heat and cold?
Ariſtotle defective
in aſſigning the
cauſes why the
ments are
ble & corruptible.
SIMPL. I know it, becauſe thoſe qualities are not amongſt
Cœleſtial bodies, which are neither hot nor cold.
SALV. I ſee we are again going about to engulph our ſelves in
a bottomleſs ocean, where there is no getting to ſhore; for this
is a Navigation without Compaſs, Stars, Oars or Rudder: ſo that
it will follow either that we be forced to paſs from Shelf to Shelf,
or run on ground, or to ſail continually in danger of being loſt.
Therefore, if according to your advice we ſhall proceed in our
main deſign, we muſt of neceſſity for the preſent overpaſs this
general conſideration, whether direct motion be neceſſary in
ture, and agree with ſome bodies; and come to the particular
demonſtrations, obſervations and experiments; propounding in
the firſt place all thoſe that have been hitherto alledged by
ſtotle, Ptolomey, and others, to prove the ſtability of the Earth,
deavouring in the next place to anſwer them: and producing in
1the laſt place, thoſe, by which others may be perſwaded, that the
Earth is no leſs than the Moon, or any other Planet to be
bered amongſt natural bodies that move circularly.
SAGR. I ſhall the more willingly incline to this, in that I am
better ſatisfied with your Architectonical and general diſcourſe,
than with that of Ariſtotle, for yours convinceth me without the
leaſt ſcruple, and the other at every ſtep croſſeth my way with
ſome block. And I ſee no reaſon why Simplicius ſhould not be
preſently ſatisfied with the Argument you alledg, to prove that
there can be no ſuch thing in nature as a motion by a right line,
if we do but preſuppoſe that the parts of the Univerſe are
ſed in an excellent conſtitution and perfect order.
SALV. Stay a little, good Sagredus, for juſt now a way comes
into my mind, how I may give Simplicius ſatisfaction, provided
that he will not be ſo ſtrictly wedded to every expreſſion of
riſtotle, as to hold it hereſie to recede in any thing from him. Nor
is there any queſtion to be made, but that if we grant the
lent diſpoſition and perfect order of the parts of the Univerſe,
as to local ſcituation, that then there is no other but the circular
motion, and reſt; for as to the motion by a right line, I ſee not
how it can be of uſe for any thing, but to reduce to their natural
conſtitution, ſome integral bodies, that by ſome accident were
mov'd and ſeparated from their whole, as we ſaid above.
Let us now conſider the whole Terreſtrial Globe, and enquire
the beſt we can, whether it, and the other Mundane bodies are to
conſerve themſelves in their perfect and natural diſpoſition. It
is neceſſary to ſay, either that it reſts and keeps perpetually
moveable in its place; or elſe that continuing always in its place,
it revolves in its ſelf; or that it turneth about a Centre, moving

by the circumference of a circle. Of which accidents, both
ſtotle and Ptolomey, and all their followers ſay, that it hath ever
obſerved, and ſhall continually keep the firſt, that is, a perpetual

reſt in the ſame place. Now, why, I pray you, ought they not
to have ſaid, that its natural affection is to reſt immoveable,
ther than to make natural unto it the motion ^{*} downwards, with
which motion it never did or ſhall move? And as to the motion

by a right line, they muſt grant us that Nature maketh uſe of it
to reduce the ſmall parts of the Earth, Water, Air, Fire, and every
other integral Mundane body to their Whole, when any of them
by chance are ſeparated, and ſo tranſported out of their proper
place; if alſo haply, ſome circular motion might not be found
to be more convenient to make this reſtitution. In my
ment, this primary poſition anſwers much better, even according
to Ariſtotles own method, to all the other conſequences, than
to attribute the ſtraight motion to be an intrinſick and natural
1principle of the Elements. Which is manifeſt, for that if I aske
the Peripatetick, if, being of opinion that Cœleſtial bodies are
incorruptibe and eternal, he believeth that the Terreſtial Globe
is not ſo, but corruptible and mortal, ſo that there ſhall come a
time, when the Sun and Moon and other Stars, continuing their
beings and operations, the Earth ſhall not be found in the
World, but ſhall with the reſt of the Elements be deſtroyed
and annihilated, I am certain that he would anſwer me, no:

therefore generation and corruption is in the parts and not in the
whole; and in the parts very ſmall and ſuperficial, which are,
as it were, incenſible in compariſon of the whole maſſe. And
becauſe Ariſtotle deduceth generation and corruption from the
contrariety of ſtreight motions, let us remit ſuch motions to the
parts, which onely change and decay, and to the whole Globe
and Sphere of the Elements, let us aſcribe either the circular
tion, or a perpetual conſiſtance in its proper place: the only
affections apt for perpetuation, and maintaining of perfect order.
This which is ſpoken of the Earth, may be ſaid with the ſame
reaſon of Fire, and of the greateſt part of the Air; to which

Elements, the Peripateticks are forced to aſcribe for intrinſical
and natural, a motion wherewith they were never yet moved,
nor never ſhall be; and to call that motion preternatural to them,
wherewith, if they move at all, they do and ever ſhall move.
This I ſay, becauſe they aſſign to the Air aud Fire the motion
upwards, wherewith thoſe Elements were never moved, but
only ſome parts of them, and thoſe were ſo moved onely in
der to the recovery of their perfect conſtitution, when they were
out of their natural places; and on the contrary they call the
circular motion preternatural to them, though they are thereby
inceſſantly moved: forgeting, as it ſeemeth, what Ariſtotle oft
culcateth, that nothing violent can be permanent.
Ariſt. & Ptolomey
make the
strial Globe
veable.
It is better to ſay,
that the
al Globe naturally
resteth, than that
it moveth directly
downwards.
*The word is, all'
ingiù, which the
Latine verſion
dreth ſurſùm,
which is quite
trary to the
thors ſenſe.
Right Motion
with more reaſon
attributed to the
parts, than to the
whole Elements.
The Peripateticks
improperly aſſign
thoſe motious to
the Elements for
Natural, with
which they never
were moved, and
thoſe for
natural with which
they alwayes are
moved.
SIMPL. To all theſe we have very pertinent anſwers, which

I for this time omit, that we may come to the more particular
reaſons, and ſenſible experiments, which ought in concluſion to
be oppoſed, as Ariſtotle ſaitn well, to whatever humane reaſon
can preſent us with.
Senſible
ments to be
red to humane
Arguments.
SAGR. What hath been ſpoken hitherto, ſerves to clear up
unto us which of the two general diſcourſes carrieth with it moſt
of probability, I mean that of Ariſtotle, which would perſwade
us, that the ſublunary bodies are by nature generable, and
ptible, &c. and therefore moſt different from the eſſence of
leftial bodies, which are impaſſible, ingenerable, incorruptible,
&c. drawn from the diverſity of ſimple motions; or elſe this of
Salviatus, who ſuppoſing the integral parts of the World to be
diſpoſed in a perfect conſtitution, excludes by neceſſary
1quence the right or ſtraight motion of ſimple natural bodies, as
being of no uſe in nature, and eſteems the Earth it ſelf alſo to
be one of the Cœleſtial bodies adorn'd with all the prerogatives
that agree with them; which laſt diſcourſe is hitherto much
more likely, in my judgment, than that other. Therefore
ſolve, Simplicius, to produce all the particular reaſons,
ments and obſervations, as well Natural as Aſtronomical, that
may ſerve to perſwade us that the Earth differeth from the
leſtial bodies, is immoveable, and ſituated in the Centre of the
World, and what ever elſe excludes its moving like to the Planets,
as Jupiter or the Moon, &c. And Salviatus will be pleaſed to
be ſo civil as to anſwer to them one by one.
SIMPL. See here for a beginning, two moſt convincing
ments to demonſtrate the Earth to be moſt different from the
Cœleſtial bodies. Firſt, the bodies that are generable,
ptible, alterable, &c. are quite different from thoſe that are
generable, incorruptible, unalterable, &c. But the Earth is
nerable, corruptible, alterable, &c. and the Cœleſtial bodies
generable, incorruptible, unalterable, &c. Therefore the Earth
is quite different from the Cœleſtial bodies.
SAGR. By your firſt Argument you ſpread the Table with the
ſame Viands, which but juſt now with much adoe were voided.
SIMPL. Hold a little, Sir, and take the reſt along with you,
and then tell me if this be not different from what you had
fore. In the former, the Minor was proved à priori, & now you ſee
it proved à poſteriori: Judg then if it be the ſame. I prove the
Minor, therefore (the Major being moſt manifeſt) by ſenſible
perience, which ſhews us that in the Earth there are made
nual generations, corruptions, alterations, &c. which neither our
ſenſes, nor the traditions or memories of our Anceſtors, ever ſaw
an inſtance of in Heaven; therefore Heaven is unalterable, &c.

and the Earth alterable, &c. and therefore different from
ven. I take my ſecond Argument from a principal and eſſential
accident, and it is this. That body which is by its nature

ſcure and deprived of light, is divers from the luminous and
ning bodies; but the Earth is obſcure and void of light, and the
Cœleſtial bodies ſplendid, and full of light; Ergo, &c. Anſwer
to theſe Arguments firſt, that we may not heap up too many,
and then I will alledge others.
Heaven
ble, becauſe there
never was any
tation ſeen in it.
Bodies naturally
lucid, are different
from thoſe which
are by nature
ſcure.
SALV. As to the firſt, the ſtreſſe whereof you lay upon
perience, I deſire that you would a little more diſtinctly produce
me the alteration which you ſee made in the Earth, and not in
Heaven; upon which you call the Earth alterable, and the
vens not ſo.
SIMPL. I ſee in the Earth, plants and animals continually
1nerating and decaying; winds, rains, tempeſts, ſtorms ariſing; and
in a word, the aſpect of the Earth to be perpetually
ſing; none of which mutations are to be diſcern'd in the Cœleſtial
bodies; the conſtitution and figuration of which is moſt
ally conformable to that they ever were time out of mind; without
the generation of any thing that is new, or corruption of any thing
that was old.
SALV. But if you content your ſelf with theſe viſible, or to
ſay better, ſeen experiments, you muſt conſequently account
China and America Cœleſtial bodies, for doubtleſſe you never
beheld in them theſe alterations which you ſee here in Italy, and
that therefore according to your apprehenſion they are
terable.
SIMPL. Though I never did ſee theſe alterations ſenfibly in
thoſe places, the relations of them are not to be queſtioned;
beſides that, cum eadem ſit ratio totius, & partium, thoſe
Countreys being a part of the Earth, as well as ours, they
muſt of neceſſity be alterable as theſe are.
SALV. And why have you not, without being put to believe
other mens relations, examined and obſerved thoſe alterations
with your own eyes?
SIMPL. Becauſe thoſe places, beſides that they are not
poſed to our eyes, are ſo remote, that our ſight cannot reach
to comprehend therein ſuch like mutations.
SALV. See now, how you have unawares diſcovered the
cy of your Argument; for, if you ſay that the alterations that
are ſeen on the Earth neer at hand, cannot, by reaſon of the too
great diſtance, be ſeen in America, much leſſe can you ſee them
in the Moon, which is ſo many hundred times more remote:
And if you believe the alterations in Mexico upon the report of
thoſe that come from thence, what intelligence have you from
the Moon, to aſſure you that there is no ſuch alterations in it?
Therefore, from your not ſeeing any alterations in Heaven,
whereas, if there were any ſuch, you could not ſee them by
ſon of their too great diſtance, and from your not having
ligence thereof, in regard that it cannot be had, you ought not
to argue, that there are no ſuch alterations; howbeit, from the
ſeeing and obſerving of them on Earth, you well argue that
therein ſuch there are.
SIMPL. I will ſhew ſo great mutations that have befaln on
the Earth; that if any ſuch had happened in the Moon, they
might very well have been obſerved here below. We find in

very antient records, that heretofore at the Streights of Gibraltar,
the two great Mountains Abila, and Calpen, were continued
gether by certain other leſſe Mountains which there gave check
1to the Ocean: but thoſe Hills, being by ſome cauſe or other
parated, and a way being opened to the Sea to break in, it made
ſuch an inundation, that it gave occaſion to the calling of it ſince
the Mid-land Sea: the greatneſs whereof conſidered, and the
vers aſpect the ſurface of the Water and Earth then made, had it
been beheld afar off, there is no doubt but ſo great a change
might have been diſcerned by one that was then in the Moon;
as alſo to us inhabitants of the Earth, the like alterations would
be perceived in the Moon; but we find not in antiquity, that
ver there was ſuch a thing ſeen; therefore we have no cauſe to
ſay, that any of the Cœleſtial bodies are alterable, &c.
The Mediterr
an Sea made by the
ſeparation of
la and Calpen.
SALV. That ſo great alterations have hapned in the Moon, I
dare not ſay, but for all that, I am not yet certain but that ſuch
changes might occur; and becauſe ſuch a mutation could onely
repreſent unto us ſome kind of variation between the more clear,
and more obſcure parts of the Moon, I know not whether we
have had on Earth obſervant Selenographers, who have for any
conſiderable number of years, inſtructed us with ſo exact
graphy, as that we ſhould confidently conclude, that there hath
no ſuch change hapned in the face of the Moon; of the
tion of which I find no more particular deſcription, than the
ing of ſome, that it repreſents an humane face; of others, that
it is like the muzzle of a lyon; and of others, that it is Cain with
a bundle of thorns on his back: therefore, to ſay Heaven is
alterable, becauſe that in the Moon, or other Cœleſtial bodies, no
ſuch alterations are ſeen, as diſcover themſelves on Earth, is a bad
illation, and concludeth nothing.
SAGR. And there is another odd kind of ſcruple in this
ment of Simplicius, running in my mind, which I would gladly
have anſwered; therefore I demand of him, whether the Earth
before the Mediterranian inundation was generable and
ble, or elſe began then ſo to be?
SIMPL. It was doubtleſs generable and corruptible alſo
fore that time; but that was ſo vaſt a mutation, that it might
have been obſerved as far as the Moon.
SAGR. Go to; if the Earth was generable and corruptible
before that Inundation, why may not the Moon be ſo
wiſe without ſuch a change? Or why ſhould that be neceſſary
in the Moon, which importeth nothing on Earth?
SALV. It is a ſhrewd queſtion: But I am doubtfull that
plicius a little altereth the Text of Ariſtotle, and the other
patelicks, who ſay, they hold the Heavens unalterable, for that
they ſee therein no one ſtar generate or corrupt, which is
bly a leſs part of Heaven, than a City is of the Earth, and yet
innumerable of theſe have been deſtroyed, ſo as that no mark of
them hath remain'd.
1
SAGR. I verily believed otherwiſe, and conceited that
plicius diſſembled this expoſition of the Text, that he might not
charge his Maſter and Conſectators, with a notion more abſurd
than the former. And what a folly it is to ſay the Cœleſtial
part is unalterable, becauſe no ſtars do generate or corrupt
in? What then? hath any ſeen a Terreſtrial Globe corrupt, and
another regenerate in its place? And yet is it not on all hands
granted by Philoſophers, that there are very few ſtars in Heaven
leſs than the Earth, but very many that are much bigger? So

that for a ſtar in Heaven to corrupt, would be no leſs than if the
whole Terreſtrial Globe ſhould be deſtroy'd. Therefore, if for
the true proof of generation and corruption in the Univerſe, it be
neceſſary that ſo vaſt bodies as a ſtar, muſt corrupt and
rate, you may ſatisfie your ſelf and ceaſe your opinion; for I
aſſure you, that you ſhall never ſee the Terreſtrial Globe or any
other integral body of the World, to corrupt or decay ſo, that
having been beheld by us for ſo many years paſt, they ſhould ſo
diſſolve, as not to leave any footſteps of them.
Its no leſs
ble for a ſtar to
corrupt, than for
the whole
ſtrial Globe.
SALV. But to give Simplicius yet fuller ſatisfaction, and to
reclaim him, if poſſible, from his error; I affirm, that we have in

our age new accidents and obſervations, and ſuch, that I queſtion
not in the leaſt, but if Ariſtotle were now alive, they would make
him change his opinion; which may be eaſily collected from the
very manner of his diſcourſing: For when he writeth that he
ſteemeth the Heavens inalterable, &c. becauſe no new thing was
ſeen to be begot therein, or any old to be diſſolved, he ſeems
plicitely to hint unto us, that when he ſhould ſee any ſuch
dent, he would hold the contrary; and confront, as indeed it is
meet, ſenſible experiments to natural reaſon: for had he not
made any reckoning of the ſenſes, he would not then from the
not ſeeing of any ſenſible mutation, have argued immutability.
Ariſtotle would
change his opinion,
did he ſee the
velties of our age.
SIMPL. Ariſtotle deduceth his principal Argument à priori,
ſhewing the neceſſity of the inalterability of Heaven by natural,
manifeſt and clear principles; and then ſtabliſheth the ſame à
ſteriori, by ſenſe, and the traditions of the antients.
SALV. This you ſpeak of is the Method he hath obſerved in
delivering his Doctrine, but I do not bethink it yet to be that
wherewith he invented it; for I do believe for certain, that he
firſt procured by help of the ſenſes, ſuch experiments and
vations as he could, to aſſure him as much as it was poſſible, of the

concluſion, and that he afterwards ſought out the means how to
demonſtrate it: For this, the uſual courſe in demonſtrative
ces, and the reaſon thereof is, becauſe when the concluſion is
true, by help of reſolutive Method, one may hit upon ſome
poſition before demonſtrated, or come to ſome principle known
1per ſe; but if the concluſion be falſe, a man may proceed in
finitum, and never meet with any truth already known; but
ry oft he ſhall meet with ſome impoſſibility or manifeſt

ty. Nor need you queſtion but that Pythagoras along time
fore he found the demonſtration for which he offered the
tomb, had been certain, that the ſquare of the ſide ſubtending
the right angle in a rectangle triangle, was equal to the ſquare of
the other two ſides: and the certainty of the concluſion
ced not a little to the inveſtigating of the demonſtration,
derſtanding me alwayes to mean in demonſtrative Sciences. But
what ever was the method of Ariſtotle, and whether his arguing à
priori preceded ſenſe à poſteriori, or the contrary; it ſufficeth that
the ſame Ariſtotle preferreth (as hath been oft ſaid) ſenſible
periments before all diſcourſes; beſides, as to the Arugments à
priori their force hath been already examined. Now returning
to my purpoſed matter, I ſay, that the things in our times
covered in the Heavens, are, and have been ſuch, that they may
give abſolute ſatisfaction to all Philoſophers; foraſmuch as in
the particular bodies, and in the univerſal expanſion of Heaven,
there have been, and are continually, ſeen juſt ſuch accidents as
we call generations and corruptions, being that excellent
ſtronomers have obſerved many Comets generated and diſſolved
in parts higher than the Lunar Orb, beſides the two new Stars,

Anuo 1572, and Anno 1604, without contradiction much higher
than all the Planets; and in the face of the Sun it ſelf, by help

of the Teleſcope, certain denſe and obſcure ſubſtances, in
blance very like to the foggs about the Earth, are ſeen to be
produced and diſſolved; and many of theſe are ſo vaſt, that
they far exceed not only the Mediterranian Streight, but all

Affrica and Aſia alſo. Now if Ariſtotle had ſeen theſe things,
what think you he would have ſaid, and done Simplicius?
The certaixty of
the concluſion
peth by areſolutive
method to ſind the
demonstration.
Pythagoras offered
an Hecatomb for
a Geometrical
monſtration which
he found.
New ſtars
vered in Heaven.
Spots generate and
diſſolve in the face
of the Sun.
Solar spots are
bigger than all
ſia and Affrick.
SIMPL. I know not what Ariſtotle would have done or ſaid,
that was the great Maſter of all the Sciences, but yet I know in
part, what his Sectators do and ſay, and ought to do and ſay,
unleſſe they would deprive themſelves of their guide, leader, and
Prince in Philoſophy. As to the Comets, are not thoſe Modern
Aſtronomers, who would make them Cœleſtial, convinced by

the ^{*}Anti-Tycho, yea, and overcome with their own weapons, I
mean by way of Paralaxes and Calculations, every way tryed,
concluding at the laſt in favour of Aristotle, that they are all
Elementary? And this being overthrown, which was as it were
their foundation, have theſe Novelliſts any thing more
with to maintain their aſſertion?
* Aſtronomers
futed by
cho.
SALV. Hold a little, good Simplicius, this modern Author,
what ſaith he to the new Stars, Anno 1572, and 1604, and to
1the Solar ſpots? for as to the Comets, I for my own particular
little care to make them generated under or above the Moon;
nor did I ever put much ſtreſſe on the loquacity of Tycho; nor
am I hard to believe that their matter is Elementary, and that
they may elevate (ſublimate) themſelves at their pleaſure,
out meeting with any obſtacle from the impenetrability of the
Peripatetick Heaven, which I hold to be far more thin, yielding,
and ſubtil than our Air; and as to the calculations of the
rallaxes, firſt, the uncertainty whether Comets are ſubject to
ſuch accidents, and next, the inconſtancy of the obſervations,
upon which the computations are made, make me equally
pect both thoſe opinions: and the rather, for that I ſee him

you call Anti-Tycho, ſometimes ſtretch to his purpoſe, or elſe
reject thoſe obſervations which interfere with his deſign.
Anti-Tycho
ſteth Aſtronomical
obſervations to his
own parpoſe.
SIMPL. As to the new Stars, Anti-Tycho extricates himſelf
finely in three or four words; ſaying, That thoſe
dern new Stars are no certain parts of the Cœleſtial bodies, and
that the adverſaries, if they will prove alteration and
tion in thoſe ſuperior bodies, muſt ſhew ſome mutations that
have been made in the Stars deſcribed ſo many ages paſt, of
which there is no doubt but that they be Cœleſtial bodies,
which they can never be able to do: Next, as to thoſe
ters which ſome affirm, to generate and diſſipate in the face of
the Sun, he makes no mention thereof; wherefore I conclude,
that he believed them fictious, or the illuſions of the Tube, or
at moſt, ſome petty effecs cauſed by the Air, and in brief, any
thing rather than matters Cœleſtial.
SALV. But you, Simplicius, what anſwer could you give to
the oppoſition of theſe importunate ſpots which are ſtarted up
to diſturb the Heavens, and more than that, the Peripatetick
Philoſophy? It cannot be but that you, who are ſo reſolute a
Champion of it, have found ſome reply or ſolution for the
ſame, of which you ought not to deprive us.
SIMPL. I have heard ſundry opinions about this particular.
One ſaith: “They are Stars which in their proper Orbs, like as

Venus and Mervury, revolve about the Sun, and in paſſing
der it, repreſent themſelves to us obſcure; and for that they
are many, they oft happen to aggregate their parts together,
and afterwards ſeperate again. Others believe them to be
aerial impreſſions; others, the illuſions of the chryſtals; and
thers, other things: But I incline to think, yea am verily
ſwaded, That they are an aggregate of many ſeveral opacous
bodies, as it were caſually concurrent among themſelves. And
therefore we often ſee, that in one of thoſe ſpots one may
number ten or more ſuch ſmall bodies, which are of
1lar figures, and ſeem to us like flakes of ſnow, or flocks of
wooll, or moaths flying: they vary ſite amongſt themſelves,
and one while ſever, another while meet, and moſt of all
neath the Sun, about which, as about their Centre, they
tinually move. But yet, muſt we not therefore grant, that
they are generated or diſſolved, but that at ſometimes they are
hid behind the body of the Sun, and at other times, though
remote from it, yet are they not ſeen for the vicinity of the
immeaſurable light of the Sun; in regard that in the eccentrick
Orb of the Sun, there is conſtituted, as it were, an Onion,
poſed of many folds one within another, each of which, being

^{*}ſtudded with certain ſmall ſpots, doth move; and albeit their
motion at firſt ſeemeth inconſtant and irregular, yet
leſſe, it is ſaid at laſt, to be obſerved that the very ſame ſpots,
as before,” do within a determinate time return again. This
ſeemeth to me the fitteſt anſwer that hath been found to aſſigne
a reaſon of that ſame appearance, and withal to maintain the
incorruptability and ingenerability of the Heavens; and if this
doth not ſuffice; there wants not more elevated wits, which will
give you other, more convincing.
Sundry opinions
touching the Solar
ſpots.
* The Original
ſaith [tempeſtata ſi
muove] which the
Latine
on, (Miſtaking
Tempectata, aword
in Heraldry, for
Tempeſtato,)
dereth [incitata
movetur] which
ſignifieth a violent
tranſportmeut, as
in a ſtorm, that of
a Ship.
SALV. If this of which we diſpute, were ſome point of Law,

or other part of the Studies called Humanity, wherein there is
neither truth nor falſhood, if we will give ſufficient credit to
the acuteneſſe of the wit, readineſſe of anſwers, and the
ral practice of Writers, then he who moſt aboundeth in theſe,
makes his reaſon more probable and plauſible; but in Natural
Sciences, the concluſions of which are true and neceſſary, and
wherewith the judgment of men hath nothing to do, one is to
be more cautious how he goeth about to maintain any thing that
is falſe; for a man but of an ordinary wit, if it be his good
tune to be of the right ſide, may lay a thouſand Demoſthenes and
a thouſand Ariſtotles at his feet. Therefore reject thoſe hopes
and conceits, wherewith you flatter your ſelf, that there can be
any men ſo much more learned, read, and verſed in Authors,
than we, that in deſpite of nature, they ſhould be able to
make that become true, which is falſe. And ſeeing that of all
the opinions that have been hitherto alledged touching the
ſence of theſe Solar ſpots, this inſtanced in by you, is in your
judgment the trueſt, it followeth (if this be ſo) that all the reſt
are falſe; and to deliver you from this alſo, which doubtleſſe is a
moſt falſe Chimœra, over-paſſing infinite other improbabilities
that are therein, I ſhall propoſe againſt it onely two experiments;

one is, that many of thoſe ſpots are ſeen to ariſe in the midſt of
the Solar ring, and many likewiſe to diſſolve and vaniſh at a great
diſtance from the circumference of the Sun; a neceſſary
1ment that they generate and diſſolve; for if without generating
or corrrupting, they ſhould appear there by onely local motion,
they would all be ſeen to enter, and paſs out by the extreme

cumference. The other obſervation to ſuch as are not ſituate in
the loweſt degree of ignorance in Perſpective, by the mutation
of the appearing figures, and by the apparent mutations of the
velocity of motion is neceſſarily concluding, that the ſpots are
contiguous to the body of the Sun, and that touching its
cies, they move either with it or upon it, and that they in no wiſe
move in circles remote from the ſame. The motion proves

it, which towards the circumference of the Solar Circle,
appeareth very ſlow, and towards the midſt, more ſwift; the
gures of the ſpots confirmeth it, which towards the circumference

appear exceeding narrow in compariſon of that which they ſeem
to be in the parts nearer the middle; and this becauſe in the
midſt they are ſeen in their full luſter, and as they truly be; and
towards the circumference by reaſon of the convexity of the
bous ſuperficies, they ſeem more compreſſ'd: And both theſe
diminutions of figure and motion, to ſuch as know how to obſerve
and calculate them exactly, preciſely anſwer to that which ſhould
appear, the ſpots being contiguous to the Sun, and differ
cileably from a motion in circles remote, though but for ſmal
intervalls from the body of the Sun; as hath been diffuſely

monſtrated by our ^{*} Friend, in his Letters about the Solar ſpots,
to Marcus Velſerus. It may be gathered from the ſame
tion of figure, that none of them are ſtars, or other bodies of
ſpherical figure; for that amongſt all figures the ſphere never
appeareth compreſſed, nor can ever be repreſented but onely
fectly round; and thus in caſe any particular ſpot were a round
body, as all the ſtars are held to be, the ſaid roundneſs would as
well appear in the midſt of the Solar ring, as when the ſpot is near
the extreme: whereas, its ſo great compreſſion, and ſhewing its
ſelf ſo ſmall towards the extreme, and contrariwiſe, ſpatious and
large towards the middle, aſſureth us, that theſe ſpots are flat

plates of ſmall thickneſs or depth, in compariſon of their length
and breadth. Laſtly, whereas you ſay that the ſpots after their
determinate periods are obſerved to return to their former aſpect,
believe it not, Simplicius, for he that told you ſo, will deceive
you; and that I ſpeak the truth, you may obſerve them to be hid
in the face of the Sun far from the circumference; nor hath your
Obſervator told you a word of that compreſſion, which
rily argueth them to be contiguous to the Sun. That which he
tells you of the return of the ſaid ſpots, is nothing elſe but what
is read in the forementioned Letters, namely, that ſome of them
may ſometimes ſo happen that are of ſo long a duration, that
1they cannot be diſſipated by one ſole converſion about the Sun,
which is accompliſhed in leſs than a moneth.
In natural
ences, the art of
Oratory is of no
force.
An Argument
that neceſſarily
proveth the Solar
ſpots to generate
and diſſolwe.
A concluſive
monſtration, that
the ſpots are
guous to the body
of the Sun.
The motion of the
spots towards the
circumference of
the Sun appears
ſlow.
The figure of the
spots appears
row towards the
circumference of
the Suns diſcus, &
why.
* Under this word
Friend, as alſo that
of Academick, &
Common Friend,
Galilœus modeſtly
conceals himſelf
throughout theſe
Dialogues.
The Solar spots
are not ſpherical,
but flat like thin
plates.
SIMPL. I, for my part, have not made either ſo long, or ſo
exact obſervations, as to enable me to boaſt my ſelf Maſter of the
Quod ect of this matter: but I will more accurately conſider the
ſame, and make tryal my ſelf for my own ſatisfaction, whether I
can reconcile that which experience ſhews us, with that which
Ariſtotle teacheth us; for it's a certain Maxim, that two Truths
cannot be contrary to one another.
SALV. If you would reconcile that which ſenſe ſheweth you,

with the ſolider Doctrines of Ariſtotle, you will find no great
ficulty in the undertaking; and that ſo it is, doth not Ariſtotle
ſay, that one cannot treat confidently of the things of Heaven,
by reaſon of their great remoteneſs?
One cannot (ſaith
Ariſtotle) ſpeak
confidently of
ven, by reaſon of
its great diſtance.
SIMPL. He expreſly ſaith
Ariſtotle prefers
ſenſe before
cination.
SALV. And doth he not likewiſe affirm, that we ought to
fer that which ſenſe demonſtrates, before all Arguments, though
in appearance never ſo well grounded? and ſaith he not this
without the leaſt doubt or hæſitation?
SIMPL. He doth ſo.
SALV. Why then, the ſecond of theſe propoſitions, which are
both the doctrine of Ariſtotle, that ſaith, that ſenſe is to take

place of Logick, is a doctrine much more ſolid and undoubted,
than that other which holdeth the Heavens to be unalterable; and
therefore you ſhall argue more Ariſtotelically, ſaying, the
vens are alterable, for that ſo my ſenſe telleth me, than if you
ſhould ſay, the Heavens are u alterable, for that Logick ſo
ded Aristotle. Furthermore, we may diſcourſe of Cœleſtial

ters much better than Ariſtotle; becauſe, he confeſſing the
ledg thereof to be difficult to him, by reaſon of their remoteneſs
from the ſenſes, he thereby acknowledgeth, that one to whom
the ſenſes can better repreſent the ſame, may philoſophate upon
them with more certainty. Now we by help of the Teleſcope,
are brought thirty or forty times nearer to the Heavens, than ever
Ariſtotle came; ſo that we may diſcover in them an hundred
things, which he could not ſee, and amongſt the reſt, theſe ſpots
in the Sun, which were to him abſolutely inviſible; therefore
we may diſcourſe of the Heavens and Sun, with more certainty
than Ariſtolte.
Its a doctrine more
agreeing with
riſtotle, to ſay the
Heavens are
able, than that
which affirms
them inalterable.
We may by help of
the Teleſcope
courſe better of
leſtial matters,
than Ariſtot.
ſelf.
SAGR. I ſee into the heart of Simplicius, and know that he is
much moved at the ſtrength of theſe ſo convincing Arguments;
but on the other ſide, when he conſidereth the great authority
which Ariſtotle hath won with all men, and remembreth the great
number of famous Interpreters, which have made it their buſineſs
to explain his ſenſe; and ſeeth other Sciences, ſo neceſſary and
1profitable to the publick, to build a great part of their eſteem
and reputation on the credit of Ariſtotle he is much puzzled and
perplexed: and methinks I hear him ſay, To whom then ſhould

we repair for the deciſion of our controverſies, if Ariſtotle were
removed from the chair? What other Author ſhould we follow
in the Schools, Academies and Studies? What Philoſopher hath
writ all the parts of Natural Philoſophy, and that ſo methodically
without omitting ſo much as one ſingle concluſion? Shall we then
overthrow that Fabrick under which ſo many paſſengers find
ſhelter? Shall we deſtroy that Aſylum, that Prytaneum,
in ſo many Students meet with commodious harbour, where
without expoſing themſelves to the injuries of the air, with the
onely turning over of a few leaves, one may learn all the
crets of Nature? Shall we diſmantle that fort in which we are
ſafe from all hoſtile aſſaults? But I pitie him no more than I do
that Gentleman who with great expence of time and treaſure,
and the help of many hundred artiſts, erects a very
ous Pallace, and afterwards beholds it ready to fall, by reaſon
of the bad foundation; but being extremely unwilling to ſee
the Walls ſtript which are adorned with ſo many beautifull
Pictures; or to ſuffer the columns to fall, that uphold the
ly Galleries; or the gilded roofs, chimney-pieces, the freizes,
the corniſhes of marble, with ſo much coſt erected, to be
ned; goeth about with girders, props, ſhoars, butteraſſes, to
vent their ſubverſion.
The Declamation
of Simplicius.
SALV. But alaſs, Simplicius as yet fears no ſuch fall, and
I would undertake to ſecure him from that miſchief at a far
leſs charge. There is no danger that ſo great a multitude of

ſubtle and wiſe Philoſophers, ſhould ſuffer themſelves to be
Hector'd by one or two, who make a little bluſtering; nay,
they will rather, without ever turning the points of their pens
againſt them, by their ſilence onely render them the object of
univerſal ſcorn and contempt. It is a fond conceit for any one
to think to introduce new Philoſophy, by reproving this or that
Author: it will be firſt neceſſary to new-mold the brains of
men, and make them apt to diſtinguiſh truth from falſhood. A
thing which onely God can do. But from one diſcourſe to another
whither are we ſtray'd? your memory muſt help to guide me into
the way again.
Peripatetick
loſophy
able.
SIMPL. I remember very well where we left. We were
upon the anſwer of Anti-Tycho, to the objections againſt the
immutability of the Heavens, among which you inſerted this
of the Solar fpots, not ſpoke of by him; and I believe you
intended to examine his anſwer to the inſtance of the New
Stars.
1
SALV. Now I remember the reſt, and to proceed, Methinks
there are ſome things in the anſwer of Anti-Tycho, worthy of
reprehenſion. And firſt, if the two New Stars, which he can do
no leſs than place in the uppermoſt parts of the Heavens, and
which were of a long duration, but finally vaniſhed, give him no
obſtruction in maintaining the inalterability of Heaven, in that
they were not certain parts thereof, nor mutations made in the
antient Stars, why doth he ſet himſelf ſo vigorouſly and earneſtly
againſt the Comets, to baniſh them by all ways from the
ſtial Regions? Was it not enough that he could ſay of them
the ſame which he ſpoke of the New ſtars? to wit, that in
gard they were no certain parts of Heaven, nor mutations made
in any of the Stars, they could no wiſe prejudice either Heaven,
or the Doctrine of Ariſtotle? Secondly, I am not very well
fied of his meaning; when he ſaith that the alterations that ſhould
be granted to be made in the Stars, would be deſtructive to the
prerogative of Heaven; namely, its incorruptibility, &c. and
this, becauſe the Stars are Cœleſtial ſubſtances, as is manifeſt
by the conſent of every one; and yet is nothing troubled that

the ſame alterations ſhould be made ^{*} without the Stars in the reſt
of the Cœleſtial expanſion. Doth he think that Heaven is no
Cœleſtial ſubſtance? I, for my part, did believe that the Stars
were called Cœleſtial bodies, by reaſon that they were in
ven, or for that they were made of the ſubſtance of Heaven;
and yet I thought that Heaven was more Cœleſtial than they; in
like ſort, as nothing can be ſaid to be more Terreſtrial, or more
fiery than the Earth or Fire themſelves. And again, in that he
ver made any mention of the Solar ſpots, which have been
dently demonſtrated to be produced, and diſſolved, and to be
neer the Sun, and to turn either with, or about the ſame, I have
reaſon to think that this Author probably did write more for others
pleaſure, than for his own ſatisfaction; and this I affirm,
much as he having ſhewn himſelf to be skilful in the
ticks, it is impoſſible but that he ſhould have been convinced by
Demonſtrations, that thoſe ſubſtances are of neceſſity
ous with the body of the Sun, and are ſo great generations and
corruptions, that none comparable to them, ever happen in the
Earth: And if ſuch, ſo many, and ſo frequent be made in the
very Globe of the Sun, which may with reaſon be held one of the
nobleſt parts of Heaven, what ſhould make us think that others
may not happen in the other
* Ex tra Stellas.
Generability and
alteration is a
greater perfection
in the Worlds
dies than the
trary qualities.
SAGR. I cannot without great admiration, nay more,
al of my underſtanding, hear it to be attributed to natural bodies,
for a great honour and perfection that they are ^{*} impaſſible,
mutable, inalterable, &c. And on the contrary, to hear it to
1be eſteemed a great imperfection to be alterable, generable,
table, &c. It is my opinion that the Earth is very noble and

mirable, by reaſon of ſo many and ſo different alterations,
tations, generations, &c. which are inceſſantly made therein;
and if without being ſubject to any alteration, it had been all
one vaſt heap of ſand, or a maſſe of Jaſper, or that in the time
of the Deluge, the waters freezing which covered it, it had
continued an immenſe Globe of Chriſtal, wherein nothing had

ever grown, altered, or changed, I ſhould have eſteemed it a
lump of no benefit to the World, full of idleneſſe, and in a
word ſuperfluous, and as if it had never been in nature; and
ſhould make the ſame difference in it, as between a living and
dead creature: The like I ſay of the Moon, Jupiter, and all the
other Globes of the World. But the more I dive into the
ſideration of the vanity of popular diſcourſes, the more empty
and ſimple I find them. And what greater folly can there be
imagined, than to call Jems, Silver and Gold pretious; and Earth
and dirt vile? For do not theſe perſons conſider, that if there

ſhould be as great a ſcarcity of Earth, as there is of Jewels and
pretious metals, there would be no Prince, but would gladly give
a heap of Diamonds and Rubies, and many Wedges of Gold,
to purchaſe onely ſo much Earth as ſhould ſuffice to plant a
mine in a little pot, or to ſet therein a China Orange, that he might
ſee it ſprout, grow up, and bring forth ſo goodly leaves, ſo
riferous flowers, and ſo delicate fruit? It is therefore ſcarcity and

plenty that make things eſteemed and contemned by the vulgar;
who will ſay that ſame is a moſt beautiful Diamond, for that it
reſembleth a cleer water, and yet will not part with it for ten
Tun of water: Theſe men that ſo extol incorruptibility,

rability, &c. ſpeak thus I believe out of the great deſire they
have to live long, and for fear of death; not confidering, that
if men had been immortal, they ſhould have had nothing to do
in the World. Theſe deſerve to meet with a Meduſa's head,

that would transform them into Statues of Dimond and Jaſper,
that ſo they might become more perfect than they are.
* Impatible.
The Earth very
noble, by reaſon of
the many
ons made therein.
The carth
ſitable and full of
idleneſſe, its
rations taken away
The Earth more
noble than Gold
and Jewels.
Scarcity and
ty enhanſe and
baſe the price of
things.
Incorruptibility
ſteemed by the
gar out of their
fear of death.
The diſparagers of
corraptibility
ſerve to be turned
into Statua's.
SALV. And it may be ſuch a Metamorphoſis would not be
together unprofitable to them; for I am of opinion that it is
ter not to diſcourſe at all, than to argue erroniouſly.
SIMPL. There is not the leaſt queſtion to be made, but that
the Earth is much more perfect, being as it is alterable, mutable,
&c. than if it had been a maſſe of ſtone; yea although it were
one entire Diamond, moſt hard and impaſſile. But look how mueh

theſe qualifications enoble the Earth, they render the Heavenly
bodies again on the other ſide ſo much the more imperfect, in
which, ſuch conditions would be ſuperfluous; in regard that the
1Cœleſtial bodies, namely, the Sun, Moon, and the other Stars,
which are ordained for no other uſe but to ſerve the Earth, need
no other qualities for attaining of that end, ſave onely thoſe of
light and motion.
The Cœleſtial
dies deſigned to
ſerve the Earth,
need no more but
motion and light.
SAGR. How? Will you affirm that nature hath produced and
deſigned ſo many vaſt perfect and noble Cœleſtial bodies,
ſible, immortal, and divine, to no other uſe but to ſerve the
ſible, frail, and mortal Earth? to ſerve that which you call the
droſſe of the World, and ſink of all uncleanneſſe? To what
purpoſe were the Cœleſtial bodies made immortal, &c. to ſerve a
frail, &c. Take away this ſubſerviency to the Earth, and the
numerable multitude of Cœleſtial bodies become wholly

ful, and ſuperfluous, ſince they neither have nor can have any
mutual operation betwixt themſelves; becauſe they are all
terable, immutable, impaſſible: For if, for Example, the Moon
be impaſſible, what influence can the Sun or any other Star have
upon her? it would doubtleſſe have far leſſe effect upon her, than
that of one who would with his looks or imagination, lignifie a
piece of Gold. Moreover, it ſeemeth to me, that whilſt the
leſtial bodies concurre to the generation and alteration of the
Earth, they themſelves are alſo of neceſſity alterable; for
wiſe I cannot underſtand how the application of the Sun or Moon
to the Earth, to effect production, ſhould be any other than to lay
a marble Statue by a Womans ſide, and from that conjunction to
expect
Celestial bodies
want an
changeable
tion upon each
ther.
Alterability, &c.
are not in the whole
Terreſtrial Globe,
but in ſome of its
parts.
SIMPL. Corruptibility, alteration, mutation, &c. are not in
the whole Terreſtrial Globe, which as to its whole, is no leſſe
nal than the Sun or Moon, but it is generable and corruptible as to
its external parts; but yet it is alſo true that likewiſe in them
neration and corruption are perpetual, and as ſuch require the
heavenly eternal operations; and therefore it is neceſſary that
the Cœleſtial bodies be eternal.
SAGR. All this is right; but if the corruptibility of the
ficial parts of the Earth be nowiſe prejudicial to the eternity of
its whole Globe, yea, if their being generable, corruptible,
able, &c. gain them great ornament and perfection; why can­

not, and ought not you to admit alteration, generation, &c.
wiſe in the external parts of the Cœleſtial Globes, adding to
them ornament, without taking from them perfection, or
ving them of action; yea rather encreaſing their effects, by
ing not onely that they all operate on the Earth, but that they
tually operate upon each other, and the Earth alſo upon them
all?
Cœleſtial bodies
alterable in their
outward parts.
SIMPL. This cannot be, becauſe the generations, mutations,
&c. which we ſhould ſuppoſe v. g. in the Moon; would be vain
and uſeleſſe, & natura nihil fruſtra facit.
1
SAGR. And why ſhould they be vain and uſeleſſe?
SIMPL. Becauſe we cleerly ſee, and feel with our hands, that

all generations, corruptions, &c. made in the Earth, are all
ther mediately or immediately directed to the uſe, convenience,
and benefit of man; for the uſe of man are horſes brought forth,
for the feeding of horſes, the Earth produceth graſſe, and the
Clouds water it; for the uſe and nouriſhment of man, herbs, corn,
fruits, beaſts, birds, fiſhes, are brought forth; and in ſum, if
we ſhould one by one dilligently examine and reſolve all theſe
things, we ſhould find the end to which they are all directed, to be
the neceſſity, uſe, convenience, and delight of man. Now of what
uſe could the generations which we ſuppoſe to be made in the
Moon or other Planets, ever be to mankind? unleſſe you ſhould
ſay that there were alſo men in the Moon, that might enjoy the
benefit thereof; a conceit either fabulous or impious.
The generations &
mutations
ing in the Earth,
are all for the good
of Man.
SAGR. That in the Moon or other Planets, there are

ted either herbs, or plants, or animals, like to ours, or that there
are rains, winds, or thunders there, as about the Earth, I
ther know, nor believe, and much leſſe, that it is inhabited by
men: but yet I underſtand not, becauſe there are not
ted things like to ours, that therefore it neceſſarily followeth,
that no alteration is wrought therein, or that there may not be
other things that change, generate, and diſſolve, which are not

onely different from ours, but exceedingly beyond our
tion, and in a word, not to be thought of by us. And if, as I
am certain, that one born and brought up in a ſpatious Forreſt,
amongſt beaſts and birds, and that hath no knowledg at all of the
Element of Water, could never come to imagine another World

to be in Nature, different from the Eatth, full of living
tures, which without legs or wings ſwiftly move, and not upon
the ſurface onely, as beaſts do upon the Earth, but in the very
bowels thereof; and not onely move, but alſo ſtay themſelves
and ceaſe to move at their pleaſure, which birds cannot do in the
air; and that moreover men live therein, and build Palaces and
Cities, and have ſo great convenience in travailing, that without
the leaſt trouble, they can go with their Family, Houſe, and
whole Cities, to places far remote, like as I ſay, I am certain,
ſuch a perſon, though of never ſo piercing an imagination, could
never fancy to himſelf Fiſhes, the Ocean, Ships, Fleets,
do's at Sea; thus, and much more eaſily, may it happn, that in
the Moon, remote from us by ſo great a ſpace, and of a
ſtance perchance very different from the Earth, there may be
ters, and operations, not only wide off, but altogether beyond
all our imaginations, as being ſuch as have no reſemblance to
ours, and therefore wholly inexcogitable, in regard, that what we
1imagine to our ſelves, muſt neceſſarily be either a thing already
ſeen, or a compoſition of things, or parts of things ſeen at
ther time; for ſuch are the Sphinxes, Sirenes, Chimœra's,
taurs, &c.
The Moon hath
no generatings of
things, like as we
have, nor is it
habited by men.
In the Moon may
be a generation of
things different
from ours.
He that had not
heard of the
ment of Water,
could never fancy
to himſelf Ships
and Fiſhes.
SALV. I have very often let my fancy ruminate upon theſe
culations, and in the end, have thought that I had found ſome
things that neither are nor can be in the Moon; but yet I
have not found therein any of thoſe which I believe are, and may
be there, ſave onely in a very general acceptation, namely, things
that adorn it by operating, moving and living; and perhaps in a way

very different from ours; beholding and admiring the greatneſs and
beauty of the World, and of its Maker and Ruler, and with
continual Encomiums ſinging his prayſes; and in ſumme (which is
that which I intend) doing what ſacred Writers ſo frequently
firm, to wit, all the creatures making it their perpetual
ment to laud God.
There may be
ſtances in the
Moon very
rent from ours.
SAGR. Theſe are the things, which ſpeaking in general terms,
may be there; but I would gladly hear you inſtance in ſuch as you
believe neither are nor can be there; which perchance may be
more particularly named.
SALV. Take notice Sagredus that this will be the third time
that we have unawares by running from one thing to another, loſt
our principal ſubject; and if we continue theſe digreſſions, it
will be longere we come to a concluſion of our diſcourſe;
fore I ſhould judg it better to remit this, as alſo ſuch other points,
to be decided on a particular occaſion.
SAGR. Since we are now got into the Moon, if you pleaſe, let
us diſpatch ſuch things as concern her, that ſo we be not forced to
ſuch another tedious journey.
SALV. It ſhall be as you would have it. And to begin with
things more general, I believe that the Lunar Globe is far
rent from the Terreſtrial, though in ſome things they agree. I will
recount firſt their reſemblances, and next their differences. The

Moon is manifeſtly like to the Earth in figure, which undoubtedly
is ſpherical, as may be neceſſarily concluded from the aſpect of its
ſurface, which is perfectly Orbicular, and the manner of its
ceiving the light of the Sun, from which, if its ſurface were flat,
it would come to be all in one and the ſame time illuminated, and
likewiſe again in another inſtant of time obſcured, and not thoſe
parts firſt, which are ſituate towards the Sun, and the reſt
ſively, ſo that in its oppoſition, and not till then, its whole
apparent circumference is enlightned; which would happen quite
contrary, if the viſible ſurface were concave; namely, the

mination would begin from the parts oppoſite or averſe to the Sun.
Secondly ſhe is as the Earth, in her ſelf obſcure and opacous, by
which opacity it is enabled to receive, and reflect the light of the
1Sun; which were it not ſo, it could not do. Thirdly, I hold its

matter to be moſt denſe and ſolid as the Earth is, which I clearly
argue from the unevenneſs of its ſuperficies in moſt places, by means
of the many eminencies and cavities diſcovered therein by help of
the ſeleſcope: of which eminencies there are many all over it,
rectly reſembling our moſt ſharp and craggy mountains, of which
you ſhall there perceive ſome extend and run in ledges of an
dred miles long; others are contracted into rounder forms; and
there are alſo many craggy, ſolitary, ſteep and cliffy rocks. But
that of which there are frequenteſt appearances, are certain Banks
(I uſe this word, becauſe I cannot thing of another that better
preſſeth them) pretty high raiſed, which environ and incloſe fields
of ſeveral bigneſſes, and form ſundry figures, but for the moſt part
circular; many of which have in the midſt a mount raiſed pretty
high, and ſome few are repleniſhed with a matter ſomewhat
ſcure, to wit, like to the great ſpots diſcerned by the bare eye, and
theſe are of the greateſt magnitude; the number moreover of thoſe
that are leſſer and leſſer is very great, and yet almoſt all circular.

Fourthly, like as the ſurface of our Globe is diſtinguiſhed into two
principal parts, namely, into the Terreſtrial and Aquatick: ſo in
the Lunar ſurface we diſcern a great diſtinction of ſome great fields
more reſplendant, and ſome leſs: whoſe aſpect makes me believe,
that that of the Earth would ſeem very like it, beheld by any one
from the Moon, or any other the like diſtance, to be illuminated

by the Sun: and the ſurface of the ſea would appear more
ſcure, and that of the Earth more bright. Fifthly, like as we from
the Earth behold the Moon, one while all illuminated, another

while half; ſometimes more, ſometimes leſs; ſometimes horned,
ſometimes wholly inviſibly; namely, when its juſt under the Sun
beams; ſo that the parts which look towards the Earth are dark:
Thus in every reſpect, one ſtanding in the Moon would ſee the
illumination of the Earths ſurface by the Sun, with the ſame
periods to an hair, and under the ſame changes of figures.
Sixtly, -----
The Firſt
blance between the
Moon and Earth;
which is that of
figure; is proved by
the manner of
ing illuminated by
the Sun.
The Second
formity is the
Moons being
cous as the Earth.
Thirdly, The
ter of the Moon is
denſe and mo
nous as the Earth.
Fourthly, The
Moon is
guiſhed into two
different parts for
clarity and
rity, as the
strial Globe into
Sea and Land.
The ſurface of the
Sea would ſhew at
a diſtance more
ſoure than that of
the Earth.
Fiftly,
tion of ſigures in
the Earth, like to
thoſe of the Moon,
and made with the
ſame periods.
SAGR. Stay a little, Salviatus; That the illumination of
the Earth, as to the ſeveral figures, would repreſent it ſelf to a perſon
placed in the Moon, like in all things to that which we diſcover in
the Moon, I underſtand very well, but yet I cannot conceive how
it ſhall appear to be done in the ſame period; ſeeing that that
which the Suns illumination doth in the Lunar ſuperficies in a
month, it doth in the Terreſtrial in twenty four hours.
SALV. Its true, the effect of the Sun about the illuminating
theſe two bodies, and repleniſhing with its ſplendor their whole
ſurfaces, is diſpatch'd in the Earth in a Natural day, and in the
Moon in a Month; but the variation of the figures in which the
1illuminated parts of the Terreſtrial ſuperficies appear beheld from
the Moon, depends not on this alone, but on the divers aſpects
which the Moon is ſtill changing with the Sun; ſo that, if for
ſtance, the Moon punctually followed the motion of the Sun, and
ſtood, for example, always in a direct line between it and the
Earth, in that aſpect which we call Conjunction, it looking always
to the ſame Hemiſphere of the Earth which the Sun looks unto,
ſhe would behold the ſame all light: as on the contrary, if it ſhould
always ſtay in Oppoſition to the Sun, it would never behold the
Earth, of which the dark part would be continually turn'd towards
the Moon, and therefore inviſible. But when the Moon is in
Quadrature of the Sun, that half of the Terreſtrial Hemiſphere
poſed to the ſight of the Moon which is towards the Sun, is
nous; and the other towards the contrary is obſcure: and
fore the illuminated part of the Earth would repreſent it ſelf to the
Moon in a ſemi-circular figure.
SAGR. I clearly perceive all this, and underſtand very well,
that the Moon departing from its Oppoſition to the Sun, where it
ſaw no part of the illumination of the Terreſtrial ſuperficies, and
approaching day by day nearer the Sun, ſhe begins by little and
little to diſcover ſome part of the face of the illuminated Earth;
and that which appeareth of it ſhall reſemble a thin ſickle, in regard
the figure of the Earth is round: and the Moon thus acquiring by
its motion day by day greater proximity to the Sun, ſucceſſively
diſcovers more and more of the Terreſtrial Hemiſphere enlightned,
ſo that at the Quadrature there is juſt half of it viſible, inſomuch
that we may ſee the other part of her: continuing next to proceed
towards the Conjunction, it ſucceſſively diſcovers more and more
of its ſurface to be illuminated, and in fine, at the time of
ction ſeeth the whole Hemiſphere enlightned. And in ſhort, I
very well conceive, that what befalls the Inhabitants of the Earth,
in beholding the changes of the Moon, would happen to him that
from the Moon ſhould obſerve the Earth; but in a contrary order,
namely, that when the Moon is to us at her full, and in Oppoſition
to the Sun, then the Earth would be in Conjunction with the Sun,
and wholly obſcure and inviſible; on the contrary, that poſition
which is to us a Conjunction of the Moon with the Sun, and for
that cauſe a Moon ſilent and unſeen, would be there an Oppoſition
of the Earth to the Sun, and, to ſo ſpeak, Full Earth, to wit, all
enlightned. And laſtly, look what part of the Lunar ſurface
pears to us from time to time illuminated, ſo much of the Earth
in the ſame time ſhall you behold from the Moon to be obſcured:
and look how much of the Moon is to us deprived of light, ſo much
of the Earth is to the Moon illuminated. In one thing yet theſe
mutual operations in my judgment ſeem to differ, and it is, that it
1being ſuppoſed, and not granted, that ſome one being placed in the
Moon to obſerve the Earth, he would every day ſee the whole
Terreſtrial ſuperficies, by means of the Moons going about the
Earth in twenty four or twenty five hours; but we never ſee but
half of the Moon, ſince it revolves not in it ſelf, as it muſt do to
be ſeen in every part of it.
SALV. So that this, befals not contrarily, namely, that her
volving in her ſelf, is the cauſe that we ſee not the other half of
her, for ſo it would be neceſſary it ſhould be, if ſhe had the
cle. But what other difference have you behind, to exchange for
this which you have named?
SAGR. Let me ſee; Well for the preſent I cannot think of
any other.
SALV. And what if the Earth (as you have well noted) ſeeth

no more than half the Moon, whereas from the Moon one may ſee
all the Earth; and on the contrary, all the Earth ſeeth the Moon, and
but onely half of it ſeeth the Earth? For the inhabitants, to ſo ſpeak,
of the ſuperior Hemiſphere of the Moon, which is to us inviſible,
are deprived of the ſight of the Earth: and theſe haply are the
Anticthones. But here I remember a particular accident, newly
obſerved by our Academian, in the Moon, from whch are gathered

two neceſſary conſequences; one is, that we ſee ſomewhat more
than half of the Moon; and the other is, that the motion of the
Moon hath exact concentricity with the Earth: and thus he finds
the Phœnomenon and obſervation. When the Moon hath a
reſpondence and natural ſympathy with the Earth, towards which
it hath its aſpect in ſuch a determinate part, it is neceſſary that the
right line which conjoyns their centers, do paſſe ever by the ſame
point of the Moons ſuperficies; ſo that, who ſo ſhall from the
ter of the Earth behold the ſame, ſhall alwayes ſee the ſame
Diſcus or Face of the Moon punctually determined by one and
the ſame circumference; But if a man be placed upon the
ſtrial ſurface, the ray which from his eye paſſeth to the centre of the
Lunar Globe, will not paſs by the ſame point of its ſuperficies, by
which the line paſſeth that is drawn from the centre of the Earth
to that of the Moon, ſave onely when it is vertical to him: but
the Moon being placed in the Eaſt, or in the Weſt, the point of
incidence of the viſual ray, is higher than that of the line which
conjoyns the centres; and therefore the obſerver may diſcern
ſome part of the Lunar Hemiſphere towards the upper
rence, and alike part of the other is inviſible: they are
ble and undiſcernable, in reſpect of the Hemiſphere beheld from
the true centre of the Earth: and becauſe the part of the Moons
circumference, which is ſuperiour in its riſing, is nethermoſt in its
ſetting; therefore the difference of the ſaid ſuperiour and
1our parts muſt needs be very obſervable; certain ſpots and other
notable things in thoſe parts, being one while diſcernable, and
another while not. A like variation may alſo be obſerved towards
the North and South extremities of the ſame Diſcus (or Surface)
according as the Moons poſition is in one or the other Section of
its Dragon; For, if it be North, ſome of its parts towards the
North are hid, and ſome of thoſe parts towards the South are
diſcovered, and ſo on the contrary. Now that theſe

ces are really true, is verified by the Teleſcope, for there be in
the Moon two remarkable ſpots, one of which, when the Moon
is in the meridian, is ſituate to the Northweſt, and the other is
almoſt diametrically oppoſite unto it; and the firſt of theſe is
ſible even without the Teleſcope; but the other is not. That
wards the Northweſt is a reaſonable great ſpot of oval figure,
parated from the other great ones; the oppoſite one is leſſe, and
alſo ſevered from the biggeſt, and ſituate in a very cleer field; in
both theſe we may manifeſtly diſcern the foreſaid variations, and
ſee them one after another; now neer the edge or limb of the
Lunar Diſcus, and anon remote, with ſo great difference that
the diſtance betwixt the Northweſt and the circumference of the
Diſcus is more than twice as great at one time, as at the other;
and as to the ſecond ſpot (becauſe it is neerer to the
rence) ſuch mutation importeth more, than twice ſo much in the
former. Hence its manifeſt, that the Moon, as if it were drawn
by a magnetick vertue, conſtantly beholds the Terreſtrial Globe
with one and the ſame aſpect, never deviating from the ſame.
All the Earth
ſeeth half onely of
the Moon, & the
half onely of the
Moon ſeeth all the
Earth.
From the Earth
we ſee more than
half the Lunar
Globe.
Two ſpots in the
Moon, by which it
is perceived that
ſhe hath respect to
the centre of the
Earth in her
tion.
SAGR. Oh! when will there be an end put to the new
ſervations aud diſcoveries of this admirable Inſtrument?
SALV. If this ſucceed according to the progreſſe of other great
inventions, it is to be hoped, that in proceſſe of time, one may
arrive to the ſight of things, to us at preſent not to be imagined.

But returning to our firſt diſcourſe, I ſay for the ſixth reſemblance
betwixt the Moon and Earth, that as the Moon for a great part
of time, ſupplies the want of the Suns light, and makes the
nights, by the reflection of its own, reaſonable clear; ſo the
Earth, in recompence, affordeth it when it ſtands in moſt need,
by reflecting the Solar rayes, a very cleer illumination, and ſo
much, in my opinion, greater than that which cometh from her to
us, by how much the ſuperficies of the Earth is greater than that
of the Moon.
Sixthly, The
Earth and Moon
interchangeably do
illuminate.
SAGR. Hold there, Salviatus hold there, and permit me the
pleaſure of relating to you, how at this firſt hint I have penetrated
the cauſe of an accident, which I have a thouſand times thought

upon, but could never find out. You would ſay, that the
fect light which is ſeen in the Moon, eſpecially when it is horned,
1comes from the reflection of the light of the Sun on the
cies of the Earth and Sea; and that light is more clear, by how
much the horns are leſſe, for then the luminous part of the Earth,
beheld by the Moon, is greater, according to that which was
a little before proved; to wit, that the luminous part of the Earth,
expoſed to the Moon, is alway as great as the obſcure part of
the Moon, that is viſible to the Earth; whereupon, at ſuch time
as the Moon is ſharp-forked, and conſequently its tenebrous part
great, great alſo is the illuminated part of the Earth beheld from
the Moon, and its reflection of light ſo much the more potent.
Light reflected
from the Earth
to the Moon.
SALV. This is exactly the ſame with what I was about to ſay.
In a word, it is a great pleaſure to ſpeak with perſons judicious
and apprehenſive, and the rather to me, for that whileſt others
converſe and diſcourſe touching Axiomatical truths, I have
ny times creeping into my brain ſuch arduous Paradoxes, that
though I have a thouſand times rehearſed this which you at the
ry firſt, have of your ſelf apprehended, yet could I never beat
it into mens brains.
SIMPL. If you mean by your not being able to perſwade them
to it, that you could not make them underſtand the ſame, I
much wonder thereat, and am very confident that if they did
not underſtand it by your demonſtration (your way of expreſſion,
being, in my judgment, very plain) they would very hardly have
apprehended it upon the explication of any other man; but if
you mean you have not perſwaded them, ſo as to make them
lieve it, I wonder not, in the leaſt, at this; for I confeſſe my
ſelf to be one of thoſe who underſtand your diſcourſes, but
am not ſatisfied therewith; for there are in this, and ſome of
the other ſix congruities, or reſemblances, many difficulties,
which I ſhall inſtance in, when you have gone through them
all.
SALV. The deſire I have to find out any truth, in the acquiſt
whereof the objections of intelligent perſons (ſuch as your ſelf)
may much aſſiſt me, will cauſe me to be very brief in diſpatching
that which remains. For a ſeventh conformity, take their

procal reſponſion as well to injuries, as favours; whereby the
Moon, which very often in the height of its illumination, by the
interpoſure of the Earth betwixt it and the Sun, is deprived of
light, and eclipſed, doth by way of revenge; in like manner,
terpoſe it ſelf between the Earth and the Sun, and with its ſhadow
obſcureth the Earth; and although the revenge be not
able to the injury, for that the Moon often continueth, and
that for a reaſonable long time, wholly immerſed in the Earths
ſhadow, but never was the Earth wholly, nor for any long time,
eclipſed by the Moon; yet, nevertheleſſe, having reſpect to the
1ſmalneſſe of the body of this, in compariſon to the magnitude
of the other, it cannot be denied but that the will and as it
were valour of this, is very great. Thus much for their
gruities or reſemblances. It ſhould next follow that we diſcourſe
touching their diſparity; but becauſe Simplicius will favour us
with his objections againſt the former, its neceſſary that we hear
and examine them, before we proceed any farther.
Seventhly, The
Earth and Moon
do mutually eclipſe.
SAGR. And the rather, becauſe it is to be ſuppoſed that
Simplicius will not any wayes oppoſe the diſparities, and
gruities betwixt the Earth and Moon, ſince that he accounts their
ſubſtances extremely different.
SIMPL. Amongſt the reſemblances by you recited, in the
rallel you make betwixt the Earth and Moon, I find that I can
admit none confidently ſave onely the firſt, and two others; I
grant the firſt, namely, the ſpherical figure; howbeit, even in
this there is ſome kind of difference, for that I hold that of the
Moon to be very ſmooth and even, as a looking-glaſſe,
as, we find and feel this of the Earth to be extraordinary
ous and rugged; but this belonging to the inequality of
cies, it ſhall be anon conſidered, in another of thoſe
ces by you alledged; I ſhall therefore reſerve what I have to ſay
thereof, till I come to the conſideration of that. Of what you
affirm next, that the Moon ſeemeth, as you ſay in your ſecond
Reſemblance, opacous and obſcure in its ſelf, like the Earth; I
admit not any more than the firſt attribute of opacity, of which
the Eclipſes of the Sun aſſure me. For were the Moon
rent, the air in the total obſcuration of the Sun, would not
come ſo duskiſh, as at ſuch a time it is, but by means of the
tranſparency of the body of the Moon, a refracted light would
paſſe through it, as we ſee it doth through the thickeſt clouds. But
as to the obſcurity, I believe not that the Moon is wholly
ved of light, as the Earth; nay, that clarity which is ſeen in the
remainder of its Diſcus, over and above the ſmall creſcent
lightened by the Sun, I repute to be its proper and natural light,

and not a reflection of the Earth, which I eſteem unable, by
reaſon of its aſperity (craggineſſe) and obſcurity, to reflect the
raies of the Sun. In the third Parallel I aſſent unto you in one

part, and diſſent in another: I agree in judging the body of the
Moon to be moſt ſolid and hard, like the Earth, yea much more;

for if from Ariſtotle we receive that the Heavens are impenetrable,
and the Stars the moſt denſe parts of Heaven, it muſt neceſſarily
follow, that they are moſt ſolid and moſt impenetrable.
The ſecond clarity
of the Moon
ſteemed to be its
native light.
The Earth unable
to reflect the Suns
raies.
The ſubſtance of
the Heavens
netrable,
ing to Ariſtotle.
SAGR. What excellent matter would the Heavens afford us for
to make Pallaces of, if we could procure a ſubſtance ſo hard and ſo
tranſparent?
1
SALV. Rather how improper, for being by its tranſparence,
wholly inviſible, a man would not be able without ſtumbling at
the threſholds, and breaking his head againſt the Walls, to paſs
from room to room.
SAGR. This danger would not befall him, if it be true, as ſome

Peripateticks ſay, that it is intangible: and if one cannot
touch it, much leſs can it hurt him.
The ſubstance of
Heaven
ble.
SALV. This would not ſerve the turn, for though the matter
of the Heavens cannot be toucht, as wanting tangible qualities:
yet may it eaſily touch the elementary bodies; and to offend us
it is as ſufficient that it ſtrike us, nay worſe, than if we ſhould
ſtrike it. But let us leave theſe Pallaces, or, to ſay better, theſe
Caſtles in the air, and not interrupt Simplicius.
SIMPL. The queſtion which you have ſo caſually ſtarted, is one
of the moſt difficulty that is diſputed in Philoſophy; and I have
on that ſubject moſt excellent conceits of a very learned Doctor
of Padoua, but it is not now time to enter upon them. Therefore
returning to our purpoſe, I ſay that the Moon, in my opinion, is
much more ſolid than the Earth, but do not infer the ſame, as you
do, from the craggineſs and montuoſity of its ſuperficies; but

rather from the contrary, namely, from its aptitude to receive (as
we ſee it experimented in the hardeſt ſtones) a poliſh and luſtre
exceeding that of the ſmootheſt glaſs, for ſuch neceſſarily muſt
its ſuperficies be, to render it apt to make ſo lively reflection of
the Suns rays. And for thoſe appearances which you mention,
of Mountains, Cliffs, Hills, Valleys, &c. they are all illuſions:
and I have been preſent at certain publick diſputes, where I have
heard it ſtrongly maintained againſt theſe introducers of novelties,

that ſuch appearances proceed from nothing elſe, but from the
equal diſtribution of the opacous and perſpicuous parts, of which
the Moon is inwardly and outwardly compoſed: as we ſee it
often fall out in chryſtal, amber, and many other precious ſtones
of perfect luſtre; in which by reaſon of the opacity of ſome parts,
and the tranſparency of others, there doth appear ſeveral
vities and prominencies. In the fourth reſemblance, I grant, that
the ſuperficies of Terreſtrial Globe beheld from afar, would make
two different appearances, namely, one more clear, the other more
dark; but I believe that ſuch diverſity would ſucceed quite
trary to what you ſay; that is, I hold that the ſurface of the
ter would appear lucid, becauſe that it is ſmooth and tranſparent;
and that of the Earth would appear obſcure, by reaſon of its
pacity and ſcabroſity, ill accommodated for reflecting the light of
the Sun. Concernïng the fifth compariſon, I grant it wholly, and
am able, in caſe the Earth did ſhine as the Moon, to ſhow the
ſame to any one that ſhould from thence above behold it,
1ſented by figures anſwerable to thoſe which we ſee in the Moon:
I comprehend alſo, how the period of its illumination and
tion of figure, would be monthly, albeit the Sun revolves round
about it in twenty four hours: and laſtly, I do not ſcruple to
admit, that the half onely of the Moon ſeeth all the Earth, and
that all the Earth ſeeth but onely half of the Moon. For what
remains, I repute it moſt falſe, that the Moon can receive light
from the Earth, which is moſt obſcure, opacous, and utterly
apt to reflect the Suns light, as the Moon doth reflect it to us: and
as I have ſaid, I hold that that light which we ſee in the
der of the Moons face (the ſplendid creſcents ſubducted) by the
illumination, is the proper and natural light of the Moon, and no
eaſie matter would induce me to believe otherwiſe. The ſeventh,
touching the mutual Eclipſes, may be alſo admitted; howbeit
that is wont to be called the eclipſe of the Sun, which you are
pleaſed to phraſe the eclipſe of the Earth. And this is what I
have at this time to ſay in oppoſition to your ſeven congruities
or reſemblances, to which objections, if you are minded to make
any reply, I ſhall willingly hear you.
The ſuperficies of
the Moon more
ſleek than any
Looking-glaß.
The eminencies
and cavities in the
Moon are illuſions
of its opacous and
perspicuous parts.
SALV. If I have well apprehended what you have anſwered, it
ſeems to me, that there ſtill remains in controverſie between us,
tain conditions, which I made common betwixt the Moon & Earth,
and they are theſe; You eſteem the Moon to be ſmooth and poliſht,
as a Looking-glaſs, and as ſuch, able to reflect the Suns light; and
contrarily, the Earth, by reaſon of its montuoſity, unable to make
ſuch reflection: You yield the Moon to be ſolid and hard, and that
you argue from its being ſmooth and polite, and not from its being
montuous; and for its appearing montuous, you aſſign as the
cauſe, that it conſiſts of parts more and leſs opacous and
cuous. And laſtly, you eſteem that ſecondary light, to be proper
to the Moon, and not reflected from the Earth; howbeit you
ſeem not to deny the ſea, as being of a ſmooth ſurface, ſome
kind of reflection. As to the convincing you of that error, that
the reflection of the Moon is made, as it were, like that of a
Looking-glaſs, I have ſmall hope, whilſt I ſee, that what hath

been read in the ^{*} Saggiator and in the Solar Letters of our
mon Friend, hath profited nothing in your judgment, if haply
you have attentively read what he hath there written on this
ject.
* Il Saggiatore, &
Lettere Solari,
two Treatiſes of
Galilæus.
SIMPL. I have peruſed the ſame ſo ſuperficially, according to
the ſmall time of leaſure allowed me from more ſolid ſtudies;
therefore, if you think you can, either by repeating ſome of thoſe
reaſons, or by alledging others, reſolve me theſe doubts, I will
hearken to them attentively.
SALV. I will tell you what comes into my mind upon the
1inſtant, and its poſſible it may be a commixtion of my own
ceipts; and thoſe which I have ſometime read in the fore-ſaid
Books, by which I well remember, that I was then perfectly
ſatisfied, although the concluſions, at firſt ſight ſeem'd unto me
ſtrange Paradoxes. We enquire Simplicius, whether to the
king a reflection of light, like that which we receive from the
Moon, it be neceſſary that the ſuperficies from whence the
ction commeth, be ſo ſmooth and polite, as the face of a
Glaſſe, or whether a ſuperficies not ſmooth or poliſht, but rough
and uneven, be more apt for ſuch a purpoſe. Now ſuppoſing
two reflections ſhould come unto us, one more bright, the other
leſſe, from two ſuperficies oppoſite unto us, I demand of you,
which of the two ſuperficies you think would repreſent it ſelf to
our ſight, to be the cleareſt, and which the obſcureſt.
SIMPL. I am very confident, that that ſame, which moſt
cibly reflected the light upon me, would ſhew its ſelf in its aſpect
the clearer, and the other darker.
SALV. Be pleaſed to take that Glaſſe which hangs on yonder

Wall, and let us go out into the Court-yard. Come Sagredus.
Now hang the glaſſe yonder, againſt that ſame Wall, on which
the Sun ſhines, and now let us with-draw our ſelves into the ſhade.
See yonder two ſuperficies beaten by the Sun, namely, the Wall
and the Glaſſe. Tell me now which appears cleareſt unto you,
that of the Wall or that of the Glaſſe? Why do you not anſwer
me?
It is proved at
large that the
Moons ſurface is
ſharp.
SAGR. I leave the reply to Simplicius, who made the
on; but I, for my own part, am perſwaded upon this ſmall
ginning of the experiment, that the Moon muſt be of a very
poliſht ſurface.
SALV. What ſay you Simplicius, if you were to depaint that
Wall, and that Glaſſe faſtened unto it, where would you uſe
your darkeſt colours, in deſigning the Wall, or elſe in painting
the Looking-Glaſſe.
SIMPL. Much the darker in depainting the Glaſſe.
SALV. Now if from the ſuperficies, which repreſents it ſelf
more clear, there proceedeth a more powerful reflection of light,
the Wall will more forcibly reflect the raies of the Sun, than the
Glaſſe.
SIMPL. Very well, Sir, have you ever a better experiment
than this? you have placed us where the Glaſſe doth not
berate upon us; but come along with me a little this way; how,
will you not ſtir?
SAGR. You perhaps ſeek the place of the reflection, which the
Glaſſe makth.
SIMPL. I do ſo.
1
SAGR. Why look you, there it is upon the oppoſite Wall, juſt
as big as the Glaſſe, and little leſſe bright than if the Sun had
directly ſhined upon it.
SIMPL. Come hither therefore, and ſee from hence the
face of the Glaſſe, and tell me whether you think it more
ſcure than that of the Wall.
SAGR. Look on it your ſelf, for I have no mind at this time,
to dazle my eyes; and I know very well, without ſeeing it,
that it there appears as ſplendid and bright as the Sun it ſelf, or
little leſſe.
SIMPL. What ſay you therefore, is the reflection of a Glaſſe
leſſe powerful than that of a Wall? I ſee, that in this oppoſite
Wall, where the reflection of the other illuminated Wall comes,
together with that of the Glaſſe, this of the Glaſſe is much
clearer; and I ſee likewiſe, that, from this place where I ſtand,
the glaſſe it ſelf appears with much more luſtre than the Wall.
SALV. You have prevented me with your ſubtlety; for I ſtood
in need of this very obſervation to demonſtrate what remains.
You ſee then the difference which happens betwixt the two
ctions made by the two ſuperficies of the Wall and Glaſſe,
cu'ſt in the ſelf-ſame manner, by the rayes of the Sun; and you
ſee, how the reflection which comes from the Wall, diffuſeth it
ſelf towards all the parts oppoſite to it, but that of the Glaſſe
goeth towards one part onely, not at all bigger than the Glaſſe
it ſelf: you ſee likewiſe, how the ſuperficies of the Wall, beheld
from what part ſoever, alwayes ſhews it ſelf of one and the ſame
cleerneſſe, and every way, much clearer than that of the Glaſſe,
excepting only in that little place, on which the Glaſſes reflection
reverberates, for from thence indeed the Glaſſe appears much more
lucid than the Wall. By theſe ſo ſenſible, and palpable
ments, my thinks one may ſoon come to know, whether the
reflection which the Moon ſends upon us, proceed as from a
Glaſſe, or elſe, as from a Wall, that is, from a ſmooth
cies, or a rugged.
SAGR. If I were in the Moon it ſelf, I think I could not with
my hands more plainly feel the unevenneſſe of its ſuperficies, than
I do now perceive it, by apprehending your diſcourſe. The Moon
beheld in any poſture, in reſpect of the Sun and us, ſheweth us
its ſuperficies, touch't by the Suns rayes, alwayes equally clear;
an effect, which anſwers to an hair that of the Wall, which
held from what place ſoever, appeareth equally bright, and
fereth from the Glaſſe, which from one place onely appeareth
cid, and from all others obſcure. Moreover, the light which
cometh to me from the reflection of the Wall, is tollerable,
and weak, in compariſon of that of the Glaſſe, which is little
1leſſe forcible and offenſive to the ſight, than that primary and
direct light of the Sun. And thus without trouble do we behold
the face of the Moon; which were it as a Glaſſe, it appearing to
us by reaſon of its vicinity, as big as the Sun it ſelf, its ſplendor
would be abſolutely intollerable, and would ſeem as if we beheld
another Sun.
SALV. Aſcribe not, I beſeech you Sagredus, more to my
monſtration, than it produceth. I will oppoſe you with an inſtance,
which I ſee not well how you can eaſily reſolve. You inſiſt upon it
as a grand difference between the Moon and Glaſſe, that it emits
its reflection towards all parts equally, as doth the Wall;
as the Glaſſe caſts it upon one onely determinate place; and from
hence you conclude the Moon to be like to the Wall, and not to
the Glaſſe: But I muſt tell you, that that ſame Glaſſe caſts its

reflection on one place onely, becauſe its ſurface is flat, and the
reflex rayes being to depart at angles equal to thoſe of the rayes
of incidence, it muſt follow that from a plane or flat ſuperficies,
they do depart unitedly towards the ſame place; but in regard
that the ſuperficies of the Moon is not plain, but ſpherical, and
the incident rayes upon ſuch a ſuperficies, being to reflect
ſelves at angles equal to thoſe of the incidence towards all parts,
by means of the infinity of the inclinations which compoſe the
ſpherical ſuperficies, therefore the Moon may ſend forth its
on every way; and there is no neceſſity for its repercuſſion upon one
place onely, as that Glaſſe which is flat.
Flat
glaſſes caſt forth
the reflection
wards but one
place, but the
ſpherical every
way.
SIMPL. This is one of the very ſame objections, which I
tended to have made againſt him.
SAGR. If this be one, you had need have more of them; yet
I tell you, that as to this firſt, it ſeems to me to make more
gainſt you, than for you.
SIMPL. You have pronounced as a thing manifeſt, that the
ction made by that Wall, is as cleer and lucid as that which the
Moon ſends forth, and I eſteem it nothing in compariſon thereto.
“For, in this buſineſſe of the illumination, its requiſite to reſpect,
and to diſtinguiſh the Sphere of Activity; and who queſtions

but the Cœleſtial bodies have greater Spheres of activity, than
theſe our elementary, frail, and mortal ones? and that Wall,
finally, what elſe is it but a little obſcure Earth, unapt to
ſhine?”
The ſphere of
Activity greater
in the Cœleſtial
bodies than in
mentary.
SAGR. And here alſo I believe, that you very much deceive your
felf. But I come to the firſt objection moved by Salviatus; and
I conſider, that to make a body appear unto us luminous, it
ficeth not that the rayes of the illuminating body fall upon it,
but it is moreover requiſite that the reflex rayes arrive to our
eye; as is manifeſtly ſeen in the example of that Glaſſe, upon
1which, without queſtion, the illuminating rayes of the Sun do
come; yet nevertheleſſe, it appears not to us bright and ſhining,
unleſſe we ſet our eye in that particular place, where the
ction arriveth. Now let us conſider what would ſucceed, were
the glaſſe of a ſpherical figure; for without doubt, we ſhould
find, that of the reflection made by the whole ſurface
ted, that to be but a very ſmall part, which arriveth to the eye
of a particular beholder; by reaſon that that is but an
rable particle of the whole ſpherical ſuperficies, the inclination
of which caſts the ray to the particular place of the eye; whence
the part of the ſpherical ſuperficies, which ſhews it ſelf ſhining
to the eye, muſt needs be very ſmall; all the reſt being
ſented obſcure. So that were the Moon ſmooth, as a

glaſſe, a very ſmall part would be ſeen by any particular eye to
be illuſtrated by the Sun, although its whole Hemiſphere were
poſed to the Suns rayes; and the reſt would appear to the eye of
the beholder as not illuminated, and therefore inviſible; and
finally, the whole Moon would be likewiſe inviſible, for ſo much
as that particle, whence the reflection ſhould come, by reaſon of
its ſmalneſſe and remoteneſſe, would be loſt. And as it would be
inviſible to the eye, ſo would it not afford any light; for it is
together impoſſible, that a bright body ſhould take away our
darkneſſe by its ſplendor, and we not to ſee it.
The Moon if it
were ſmooth, like a
ſpherical glaſſe,
would be inviſible.
SALV. Stay good Sagredus, for I ſee ſome emotions in
the face and eyes of Simplicius, which are to me as indices that
he is not either very apprehenſive of, or ſatisfied with this which
you, with admirable proof, and abſolute truth have ſpoken.
And yet I now call to mind, that I can by another experiment
remove all ſcruple. I have ſeen above in a Chamber, a great
ſpherical Looking-glaſſe; let us ſend for it hither, and whileſt it
is in bringing, let Simplicius return to conſider, how great the
clarity is which cometh to the Wall here, under the penthouſe,
from the reflection of the flat glaſſe.
SIMPL. I ſee it is little leſſe ſhining, than if the Sun had
rectly beat upon it.
SALV. So indeed it is. Now tell me, if taking away that ſmall
flat glaſſe, we ſhould put that great ſpherical one in the ſame
place, what effect (think you) would its reflection have upon the
ſame Wall?
SIMPL. I believe that it would eject upon it a far greater and
more diffuſed light.
SALV. But if the illumination ſhould be nothing, or ſo
ſmall, that you would ſcarſe diſcern it, what would you ſay
then?
SIMPL. When I have ſeen the effect, I will bethink my ſelf
of an anſwer.
1
SALV. See here is the glaſſe, which I would have to be placed
cloſe to the other. But firſt let us go yonder towards the reflection
of that flat one, and attentively obſerve its clarity; ſee how
bright it is here where it ſhines, and how diſtinctly one may diſcern
theſe ſmall unevenneſſes in the Wall.
SIMPL. I have ſeen and very well obſerved the ſame, now place
the other glaſſe by the ſide of the firſt.
SALV. See where it is. It was placed there aſſoon as you
gan to look upon the Walls ſmall unevenneſſes, and you
ved it not, ſo great was the encreaſe of the light all over the reſt of
the Wall. Now take away the flat glaſſe. Behold now all
ction removed, though the great convex glaſſe ſtill remaineth.
Remove this alſo, and place it there again if you pleaſe, and you
ſhall ſee no alteration of light in all the Wall. See here then
monſtrated to ſenſe, that the reflection of the Sun, made upon a
ſpherical convex glaſſe, doth not ſenſibly illuminate the places neer
unto it. Now what ſay you to this experiment?
SIMPL. I am afraid that there may be ſome Leigerdemain,
uſed in this affair; yet in beholding that glaſſe I ſee it dart forth
a great ſplendor, which dazleth my eyes; and that which
ports moſt of all, I ſee it from what place ſoever I look upon it;
and I ſee it go changing ſituation upon the ſuperficies of the glaſſe,
which way ſoever I place my ſelf to look upon it; a neceſſary
gument, that the light is livelily reflected towards every ſide, and
conſequently, as ſtrongly upon all that Wall, as upon my eye.
SALV. Now you ſee how cautiouſly and reſervedly you ought
to proceed in lending your aſſent to that, which diſcourſe alone
preſenteth to you. There is no doubt but that this which you ſay,
carrieth with it probability enough, yet you may ſee, how
ble experience proves the contrary.
SIMPL. How then doth this come to paſs?
SALV. I will deliver you my thoughts thereof, but I cannot
tell how you may be pleaſ'd therewith. And firſt, that lively
ſplendor which you ſee upon the glaſs, and which you think
pieth a good part thereof, is nothing near ſo great, nay is very
ceeding ſmall; but its livelineſs occaſioneth in your eye, (by means
of the reflection made on the humidity of the extream parts of the
eye-brows, which diſtendeth upon the pupil) an adventitious
ation, like to that blaze which we think we ſee about the flame of
a candle placed at ſome diſtance; or if you will, you may
reſemble it to the adventitious ſplendor of a ſtar; for if you ſhould

compare the ſmall body v. g. of the Canicula, ſeen in the day time
with the Teleſcope, when it is ſeen without ſuch irradiation, with
the ſame ſeen by night by the eye it ſelf, you will doubtleſs
prehend that being irradiated, it appeareth above a thouſand
1times bigger than the naked and real body: and a like or greater
augmentation doth the image of the Sun make, which you ſee in
that glaſs. I ſay greater, for that it is more lively than the ſtar,
as is manifeſt from our being able to behold the ſtar with much
leſs offence, than this reflection of the glaſs. The reverberation
therefore which is to diſpere it ſelf all over this wall, cometh from
a ſmall part of that glaſs, and that which even now came from
the whole flat glaſs diſperſed and reſtrain'd it ſelf to a very ſmall
part of the ſaid wall. What wonder is it then, that the firſt
flection very lively illuminates, and that this other is almoſt
perceptible?
The ſmall body of
the ſtars fringed
round about with
rays, appeareth
ry much biggerthan
plain and naked,
and in its native
clarity.
SIMPL. I find my ſelf more perplexed than ever, and there
preſents it ſelf unto me the other difficulty, how it can be that
that wall, being of a matter ſo obſcure, and of a ſuperficies ſo
poliſh'd, ſhould be able to dart from it greater light, than a glaſs
very ſmooth and polite.
SALV. Greater light it is not, but more univerſal; for as to
the degree of brightneſs, you ſee that the reflection of that ſmall
flat glaſs, where it beamed forth yonder under the ſhadow of the
penthouſe, illuminateth very much; and the reſt of the wall which
receiveth the reflection of the wall on which the glaſs is placed,
is not in any great meaſure illuminated, as was the ſmall part on
which the reflection of the glaſs fell. And if you would
ſtand the whole of this buſineſs, you muſt conſider that the

ficies of that wall's being rough, is the ſame as if it were
ſed of innumerable ſmall ſuperficies, diſpoſed according to
numerable diverſities of inclinations: amongſt which it
rily happens, that there are many diſpoſed to ſend forth their
reflex rays from them into ſuch a place, many others into another:
and in ſum, there is not any place to which there comes not very
many rays, reflected from very many ſmall ſuperficies, diſperſed
throughout the whole ſuperficies of the rugged body, upon which
the rays of the Sun fall. From which it neceſſarily
eth, That upon any, whatſoever, part of any ſuperficies,
oppoſed to that which receiveth the primary incident rays,
there is produced reflex rays, and conſequently
nation. There doth alſo follow thereupon, That the ſame
body upon which the illuminating rays fall, beheld from
whatſoever place, appeareth all illuminated and ſhining: and
therefore the Moon, as being of a ſuperficies rugged and

not ſmooth, beameth forth the light of the Sun on every
ſide, and to all beholders appeareth equally lucid. But if
the ſurface of it, being ſpherical, were alſo ſmooth as a glaſs, it
would become wholly inviſible; foraſmuch as that ſmall part,
from which the image of the Sun ſhould be reflected unto the eye
1of a particular perſon, by reaſon of its great diſtance would be
viſible, as I have ſaid before.
The reflex light
of uneven bodies, is
more univerſal
than that of the
ſmooth, & why.
The Moon, if it
were ſmooth and
ſleek, would be
viſible.
SIMPL. I am very apprehenſive of your diſcourſe; yet
thinks I am able to reſolve the ſame with very little trouble; and
eaſily to maintain, that the Moon is rotund and polite, and that it
reflects the Suns light unto us in manner of a glaſs; nor
fore ought the image of the Sun to be ſeen in the middle of it,
aſmuch as the ſpecies of the Sun it ſelf admits not its ſmall figure
to be ſeen at ſo great a diſtance, but the light produced by the
Sun may help us to conceive that it illuminateth the whole
nar Body: a like effect we may ſee in a plate gilded and well
polliſh'd, which touch't by a luminous body, appeareth to him
that beholds it at ſome diſtance to be all ſhining; and onely near
at hand one may diſcover in the middle of it the ſmall image of
the luminous body.”
SALV. Ingenuouſly confeſſing my dullneſs of apprehenſion,
I muſt tell you, that I underſtand not any thing of this your
courſe, ſave onely what concerns the gilt plate: and if you permit
me to ſpeak freely, I have a great conceit that you alſo underſtand
not the ſame, but have learnt by heart thoſe words written by ſome
one out of a deſire of contradiction, and to ſhew himſelf more
ligent than his adverſary; but it muſt be to thoſe, which to appear
alſo more wiſe, applaud that which they do not underſtand, and
entertain a greater conceit of perſons, the leſs they are by them
underſtood: and the writer himſelf may be one of thoſe (of which
there are many) who write what they do not underſtand, and

conſequently underſtand not what they write. Therefore,
mitting the reſt, I reply, as to the gilt plate, that if it be flat and
not very big, it may appear at a diſtance very bright, whilſt a great
light beameth upon it, but yet it muſt be when the eye is in a
terminate line, namely in that of the reflex rays: and it will
pear the more ſhining, if it were v. g. of ſilver, by means of its
being burniſhed, and apt through the great denſity of the metal,
to receive a perfect poliſh. And though its ſuperficies, being very
well brightned, were not exactly plain, but ſhould have various
clinations, yet then alſo would its ſplendor be ſeen many ways;
namely, from as many places as the various reflections, made by
the ſeveral ſuperficies, do reach: for therefore are Diamonds

ground to many ſides, that ſo their pleaſing luſtre might be beheld
from many places. But if the Plate were very big, though it ſhould
be all plain, yet would it not at a diſtance appear all over ſhining:
and the better to expreſs my ſelf, Let us ſuppoſe a very large gilt
plate expoſed to the Sun, it will ſhew to an eye far diſtant, the
image of the Sun, to occupy no more but a certain part of the ſaid
plate; to wit, that from whence the reflection of the incident
1ſolar rays come: but it is true that by the vivacity of the light, the
ſaid image will appear fringed about with many rays, and ſo will
ſeem to occupie a far greater part of the plate, than really it doth.
And to ſhew that this is true, when you have noted the particular
place of the plate from whence the reflection cometh, and
ved likewiſe how great the ſhining place appeared to you, cover the
greater part of that ſame ſpace, leaving it only viſible about the
midſt; and all this ſhall not any whit diminiſh the apparent
dor to one that beholds it from afar; but you ſhall ſee it largely
diſpers'd upon the cloth or other matter, wherewith you covered
it. If therefore any one, by ſeeing from a good diſtance a ſmall
gilt plate to be all over ſhining, ſhould imagine that the ſame
would alſo even in a plate as broad as the Moon, he is no leſs
ceived, than if he ſhould believe the Moon to be no bigger than
the bottom of a tub. If again the plate were turn'd into a
rical ſuperficies, the reflection would be ſeen ſtrong in but one ſole
particle of it; but yet by reaſon of its livelineſs, it will appear
fringed about with many glittering rays: the reſt of the Ball would
appear according as it was burniſhed; and this alſo onely then

when it was not very much poliſhed, for ſhould it be perfectly
brightned, it would appear obſcure. An example of this we
have dayly before our eyes in ſilver veſſels, which whilſt they are
only boyl'd in the Argol and Salt, they are all as white as ſnow, and
do not reflect any image; but if they be in any part burniſh'd, they
become in that place preſently obſcure: and in them one may ſee the
repreſentation of any thing as in Looking-glaſſes. And that
to obſcurity, proceeds from nothing elſe but the ſmoothing and
plaining of a fine grain, which made the ſuperficies of the ſilver
rough, and yet ſuch, as that it reflected the light into all parts,
whereby it ſeemed from all parts equally illuminated: which
ſmall unevenneſſes, when they come to be exquiſitely plained by
the burniſh, ſo that the reflection of the rays of incidence are all
directed unto one determinate place; then, from that ſame place,
the burniſh'd part ſhall ſhew much more bright and ſhining than
the reſt which is onely whitened by boyling; but from all other
places it looks very obſcure. And note, that the diverſity of

ſights of looking upon burniſh'd ſuperficies, occaſioneth ſuch
difference in appearances, that to imitate and repreſent in picture,
v. g. a poliſh'd Cuirace, one muſt couple black plains with white,
one ſideways to the other, in thoſe parts of the arms where the
light falleth equally.
Some write what
they underſtand
not, and therefore
underſtand not
what they write.
Diamonds ground
to divers ſides, &
why.
Silver burniſhed
appears more
ſcuee, than the not
burniſhed, & why.
Burniſh'd Steel
beheld from one
place appears very
bright, and from
another, very
ſcure.
SAGR. If therefore theſe great Philoſophers would acquieſe
in granting, that the Moon, Venus and the other Planets, were not
of ſo bright and ſmooth a ſurface as a Looking-glaſs, but wanted
ſome ſmall matter of it, namely, were as a ſilver plate, onely boyled
1white, but not burniſhed; would this yet ſuffice to the making
of it viſible, and apt for darting forth the light of the Sun?
SALV. It would ſuffice in part; but would not give a light ſo
ſtrong, as it doth being mountainous, and in ſum, full of
eminencies and great cavities. But theſe Philoſophers will never
yield it to be leſſe polite than a glaſſe; but far more, if more it
can be imagined; for they eſteeming that to perfect bodies perfect
figures are moſt ſutable; it is neceſſary, that the ſphericity of thoſe
Cœleſtial Globes be moſt exact; beſides, that if they ſhould
grant me ſome inequality, though never ſo ſmall, I would not
ſcruple to take any other greater; for that ſuch perfection
ing in indiviſibles, an hair doth as much detract from its perfection
as a mountain.
SAGR. Here I meet with two difficulties, one is to know the
reaſon why the greater inequality of ſuperficies maketh the
ger reflection of light; the other is, why theſe Peripatetick
tlemen are for this exact figure.
SALV. I will anſwer to the firſt; and leave to Simplieius the

care of making reply to the ſecond. You muſt know therefore,
that the ſame ſuperficies happen to be by the ſame light more or leſs
illuminated, according as the rayes of illumination fall upon them

more or leſſe obliquely; ſo that the greateſt illumination is where
the rayes are perpendicular. And ſee, how I will prove it to your
ſenſe. I bend this paper, ſo, that one part of it makes an angle
upon the other: and expoſing both theſe parts to the reflection of
the light of that oppoſite Wall, you ſee how this ſide which
ceiveth the rayes obliquely, is leſſe ſhining than this other, where
the reflection fals at right angles; and obſerve, that as I by
degrees receive the illumination more obliquely, it groweth
weaker.
The more rough
ſuperficies make
greater reflection
of light, than the
leſs rough.
Perpendicular
rays illuminate
more than the
lique, and why.
SAGR. I ſee the effect, but comprehend not the cauſe.
SALV. If you thought upon it but a minute of an hour, you
would find it; but that I may not waſte the time, ſee a kind of
demonſtration thereof in Fig. 7.
SAGR. The bare ſight of this Figure hath fully ſatisfied me,
therefore proceed.
SIMPL. Pray you let me hear you out, for I am not of ſo
quick an apprehenſion.
SALV. Fancie to your ſelf, that all the paralel lines, which you
ſee to depart from the terms A. B. are the rays which fall upon the

line C. D. at right angles: then incline the ſaid C. D. till it hang
as D. O. now do not you ſee that a great part of thoſe rays which
peirce C. D. paſs by without touching D. O? If therefore D. O.
be illuminated by fewer rays, it is very reaſonable, that the light
received by it be more weak. Let us return now to the Moon,
1which being of a ſpherical figure, if its ſuperficies were ſmooth, as
this paper, the parts of its hemiſphere illuminated by the Sun,
which are towards its extremity, would receive much leſs light,
than the middle parts; the rays falling upon them moſt obliquely,
and upon theſe at right angles; whereupon at the time of full
Moon, when we ſee almoſt its whole Hemiſphere illuminated, the
parts towards the midſt, would ſhew themſelves to us with more
ſplendor, than thoſe others towards the circumference: which is
not ſo in effect. Now the face of the Moon being repreſented
to me full of indifferent high mountains, do not you ſee how their
tops and continuate ridges, being elevated above the convexity of
the perfect ſpherical ſuperficies, come to be expoſed to the view
of the Sun, and accommodated to receive its rays much leſs
liquely, and conſequently to appear as luminous as the reſt?
The more oblique
Rayes illuminate
leß, and why.
SAGR. All this I well perceive: and if there are ſuch
tains, its true, the Sun will dart upon them much more directly
than it would do upon the inclination of a polite ſuperficies: but
it is alſo true, that betwixt thoſe mountains all the valleys would
become obſcure, by reaſon of the vaſt ſhadows, which in that
time would be caſt from the mountains, whereas the parts towards
the middle, though full of valleys and hills, by reaſon they have
the Sun elevated, would appear without ſhadow, and therefore
more lucid by far than the extreme parts, which are no leſs
ſed with ſhadow than light, and yet we can perceive no ſuch
rence.
SIMPL. I was ruminating upon the like difficulty.
SALV. How much readier is Simplicius to apprehend the
jections which favour the opinions of Ariſtotle, than their
ons? I have a kind of ſuſpition, that he ſtrives alſo ſometimes to
diſſemble them; and in the preſent caſe, he being of himſelf able
to hit upon the doubt, which yet is very ingenious, I cannot
lieve but that he alſo was adviſ'd of the anſwer; wherefore I will
attempt to wreſt the ſame (as they ſay) out of his mouth.
fore tell me, Simplicius, do you think there can be any ſhadow,
where the rays of the Sun do ſhine?
SIMPL. I believe, nay I am certain that there cannot; for that
it being the grand luminary, which with its rays driveth away
neſs, it is impoſſible any tenebroſity ſhould remain where it
eth; moreover, we have the definition, that Tenebræ ſunt
tio luminis.
SALV. Therefore the Sun, beholding the Earth, Moon or
ther opacous body, never ſeeth any of its ſhady parts, it not
ving any other eyes to ſee with, ſave its rays, the conveyers of
light: and conſequently, one ſtanding in the Sun would never
ſee any thing of umbrage, foraſmuch as his viſive rays would ever
1go accompanied with thoſe illuminating beams of the Sun.
SIMPL. This is true, without any contradiction.
SALV. But when the Moon is oppoſite to the Sun, what
ference is there between the tract of the rayes of your ſight, and
that motion which the Suns rayes make?
SIMPL. Now I underſtand you; for you would ſay, that the
rayes of the ſight and thoſe of the Sun, moving by the ſame lines,
we cannot perceive any of the obſcure valleys of the Moon. Be
pleaſed to change this your opinion, that I have either ſimulation
or diſſimulation in me; for I proteſt unto you, as I am a
man, that I did not gueſſe at this ſolution, nor ſhould I have
thought upon it, without your help, or without long ſtudy.
SAGR. The reſolutions, which between you two have been
alledged touching this laſt doubt, hath, to ſpeak the truth,
ed me alſo. But at the ſame time this conſideration of the
fible rayes accompanying the rayes of the Sun, hath begotten in me
another ſcruple, about the other part, but I know not whether I
can expreſſe it right, or no: for it but juſt now comming into my
mind, I have not yet methodized it to my mind: but let us ſee if
we can, all together, make it intelligible. There is no queſtion,
but that the parts towards the circumference of that poliſh't, but not
burniſh't Hemiſphere, which is illuminated by the Sun, receiving the
rayes obliquely, receive much fewer thereof, than the
moſt parts, which receive them directly. And its poſſible, that a
tract or ſpace of v. g. twenty degrees in breadth, and which is
wards the extremity of the Hemiſphere, may not receive more rays
than another towards the middle parts, of but four degree broad:
ſo that that doubtleſs will be much more obſcure than this; and
ſuch it will appear to whoever ſhall behold them both in the face,
or (as I may ſay) in their full magnitude. But if the eye of the
beholder were conſtituted in ſuch a place, that the breadth of the
twenty degrees of the obſcure ſpace, appeared not to it longer
than one of four degrees, placed in the midſt of the Hemiſphere,
I hold it not impoſſible for it to appear to the ſaid beholder
qually clear and lucid with the other; becauſe, finally, between
two equal angles, to wit, of four degrees apiece, there come to
the eye the reflections of two equal numbers of rayes: namely,
thoſe which are reflected from the middlemoſt ſpace, four degrees
in breadth, and thoſe reflected from the other of twenty degrees,
but ſeen by compreſſion, under the quantity of four degrees: and
ſuch a ſituation ſhall the eye obtain, when it is placed between the
ſaid Hemiſphere, and the body which illuminates it; for then the
ſight and rayes move in the ſame lines. It ſeemeth not impoſſible
therefore, but that the Moon may be of a very equal ſuperficies;
and that nevertheleſſe, it may appear when it is at the full, no leſs
1light in the extremities, than in the middle parts.
SALV. The doubt is ingenious and worthy of conſideration;
and as it but juſt now came into your mind unawares, ſo I will
like wiſe anſwer with what firſt comes into my thoughts, and it may
happily fall out, that by thinking more upon it, I may ſtumble
upon a better reply. But before, that I labyrinth my ſelf any
ther, it would be neceſſary, that we aſſure our ſelves by ſome
periment, whether your objection prove in effect, what it ſeemeth
to conclude in appearance; and therefore taking once more the
ſame paper, and making it to incline, by bending a little part
thereof upon the remainder, let us try whether expoſing it to the
Sun, ſo that the rayes of light fall upon the leſſer part directly,
and upon the other obliquely; this which receiveth the rayes
ly appeareth more lucid; and ſee here by manifeſt experience,
that it is notably more clear. Now if your objection be concluſive,
it will follow, that ſtooping with our eye ſo, that in beholding
the other greater part, leſs illuminated, in compreſſion or
ſhortning, it appear unto us no bigger than the other, more ſhining;
and that conſequently, it be not beheld at a greater angle than
that; it will neceſſarily enſue, I ſay, that its light be encreaſed, ſo
that it do ſeem to us as bright as the other. See how I behold, and
look upon it ſo obliquely, that it appeareth to me narrower than
the other; but yet, notwithſtanding its obſcurity, doth not to
my perceiving, at all grow clearer. Try now if the ſame ſucceed
to you.
SAGR. I have look't upon it, and though I have ſtooped with
my eye, yet cannot I ſee the ſaid ſuperficies encreaſe in light or
clarity; nay me thinks it rather grows more dusky.
SALV. We are hitherto confident of the invalidity of the
jection; In the next place, as to the ſolution, I believe, that, by
reaſon the Superficies of this paper is little leſſe than ſmooth, the
rayes are very few, which be reflected towards the point of
dence, in compariſon of the multitude, which are reflected
wards the oppoſite parts; and that of thoſe few more and more
are loſt, the nearer the viſive rayes approach to thoſe lucid rayes
of incidence; and becauſe it is not the incident rayes, but thoſe
which are reflected to the eye, that make the object appear
minous; therefore, in ſtooping the eye, there is more loſt than got,
as you your ſelf confeſſe to have ſeen in looking upon the
rer part of the paper.
SAGR. I reſt ſatisfied with this experiment and reaſon: It
mains now, that Simplicius anſwer to my other queſtion, and tell
me what moves the Peripateticks to require this ſo exact rotundity
in the Cœleſtial bodies.
SIMPL. The Cœleſtial bodies being ingenerable, inalterable,
1paſſible, immortal, &c. they muſt needs be abſolutely perfect; and

their being abſolute perfect, neceſſarily implies that there is in them
all kinds of perfection; and conſequently, that their figure be alſo
perfect, that is to ſay, ſpherical; and abſolutely and perfectly
ſpherical, and not rough and irregular.
Perfect ſphericity
why aſcribed to
Cœlestial bodies,
by the
ticks.
SALV. And this incorruptibility, from whence do you prove
it?
SIMPL. Immediately by its freedom from contraries, and
diately, by its ſimple circular motion.
SALV. So that; by what I gather from your diſcourſe, in

king the eſſence of the Cœleſtial bodies to be incorruptible,
terable, &c, there is no need of rotundity as a cauſe, or
ſite; for if this ſhould cauſe inalterability, we might at our
ſure make wood, wax, and other Elementary matters,
tible, by reducing them to a ſpherical figure.
The Figure is not
the cauſe of
ruptibility, but of
longer duration.
SIMPL. And is it not manifeſt that a ball of Wood will better
and longer be preferved, than an oblong, or other angular
gure, made of a like quantity of the ſame wood.
SALV. This is moſt certain, but yet it doth not of corruptible
become incorruptible, but ſtill remains corruptible, though of a
much longer duration. Therefore you muſt note, that a thing

ruptible, is capable of being more or leſſe ſuch, and we may
properly ſay this is leſſe corruptible than that; as for example, the
Jaſper, than the Pietra Sirena; but incorruptibility admits not
of more, or leſſe, ſo as that it may be ſaid this is more
ble than that, if both be incorruptible and eternal. The

ſity of figure therefore cannot operate: ſave onely in matters
pable of more or leſſe duration; but in the eternal, which
not be other than equally eternal, the operation of figure ceaſeth.
And therefore, ſince the Cœleſtial matter is not incorruptible by
figure, but otherwayes no man needs to be ſo ſolicitous for this
perfect ſphericity; for if the matter be incorruptible, let it have
what figure it will, it ſhall be alwayes ſuch.
Corruptibility
mits of more or
leſſe; ſo doth noe
incorruptibiliiy.
The perfection of
figure, operateth
in corruptible
dies, but not in the
eternal.
SAGR. But I am conſidering another thing, and ſay, that if

we ſhould grant the ſpherical figure a faculty of conferring
ruptibility, all bodies of whatſoever figure, would be
ble; foraſmuch as if the rotund body be incorruptible,
bility would then ſubſiſt in thoſe parts which alter the perfect
tundity; as for inſtance, there is in a Die a body perfectly round,
and, as ſuch, incorruptible; therefore it remaineth that thoſe
gles be corruptible which cover and hide the rotundity; ſo that
the moſt that could happen, would be, that thoſe angles, and
(to ſo ſpeak) excreſcencies, would corrupt. But if we proceed to a
more inward conſideration, that in thoſe parts alſo towards the
angles, there are compriſed other leſſer bals of the ſame matter;
1and therefore they alſo, as being round, muſt be alſo
tible; and likewife in the remainders, which environ theſe eight
leſſer Spheres, a man may underſtand that there are others: ſo
that in the end, reſolving the whole Die into innumerable balls,
it muſt neceſſarily be granted incorruptible. And the ſame
courſe and reſolution may be made in all other figures.
If the ſpherical
gure conferreth
ternity, all bodies
would be eternal.
SALV. Your method in making the concluſion, for if v. g. a
round Chryſtal were, by reaſon of its figure, incorruptible; namely,
received from thence a faculy of reſiſting all internal and external
alterations, we ſhould not find, that the joyning to it other
ſtal, and reducing it v. g. into a Cube, would any whit alter it
within, or without; ſo as that it would thereupon become leſſe
apt to reſiſt the new ambient, made of the ſame matter, than it
was to reſiſt the other, of a matter different; and eſpecially, if
it be true, that corruption is generated by contraries, as
ſtotle ſaith; and with what can you encloſe that ball of Cryſtal,
that is leſſe contrary to it, than Cryſtal it ſelf? But we are not
ware how time flies away; and it will be too late before we come
to an end of our diſpute, if we ſhould make ſo long diſcourſes,
upon every particular; beſides our memories are ſo confounded
in the multiplicity of notions, that I can very hardly recal to
mind the Propotſiions, which I propoſed in order to Simplicius,
for our conſideration.
SIMPL. I very well remember them: And as to this particular
queſtion of the montuoſity of the Moon, there yet remains
anſwered that which I have alledged, as the cauſe, (and which
may very well ſerve for a ſolution) of that Phænomenon, ſaying,
that it is an illuſion proceeding from the parts of the Moon,
ing unequally opacous, and perſpicuous.
SAGR. Even now, when Simplicius aſcribed the apparent
tnberancies or unevenneſſes of the Moon (according to the opinion
of a certain Peripatetick his friend) to the diverſly opacous, and

perſpicuous parts of the ſaid Moon, conformable to which the like
illuſions are ſeen in Cryſtal, and Jems of divers kinds, I bethought
my ſelf of a matter much more commodious for the repreſenting
ſuch effects; which is ſuch, that I verily believe, that that
pher would give any price for it; and it is the mother of Pearl, which
is wrought into divers figures, and though it be brought to an
treme evenneſſe, yet it ſeemeth to the eye in ſeveral parts, ſo
ouſly hollow and knotty, that we can ſcarce credit our feeling of
their evenneſſe.
Mother of Pearl
accommodated to
imitate the
rent unevenneſſes
of the Moons
face.
SALV. This invention is truly ingenious; and that which hath
not been done already, may be done in time to come; and if
there have been produced other Jems, and Cryſtals, which have
nothing to do with the illuſions of the mother of Pearl, theſe may
1be produced alſo; in the mean time, that I may not prevent any
one, I will ſuppreſſe the anſwer which might be given, and onely
for this time betake my ſelf to ſatisfie the objections brought by
Simplicius. I ſay therefore, that this reaſon of yours is too
neral, and as you apply it not to all the appearances one by one;
which are ſeen in the Moon, and for which my ſelf and others
are induced to hold it mountainous, I believe you will not find
any one that will be ſatisfied with ſuch a doctrine; nor can I think,
that either you, or the Author himſelf, find in it any greater
quietude, than in any other thing wide from the purpoſe. Of the

very many ſeveral appearances which are ſeen night by night in
the courſe of Moon, you cannot imitate ſo much as one, by making
a Ball at your choice, more or leſs opacous and perſpicuous, and
that is of a polite ſuperficies; whereas on the contrary, one may

make Balls of any ſolid matter whatſoever, that is not tranſparent,
which onely with eminencies and cavities, and by receiving the
lumination ſeveral ways, ſhall repreſent the ſame appearances and
mutations to an hair, which from hour to hour are diſcovered in

the Moon. In them you ſhall ſee the ledges of Hills expoſed to
the Suns light, to be very ſhining, and after them the projections
of their ſhadows very obſcure; you ſhall ſee them greater and leſs,
according as the ſaid eminencies ſhall be more or leſs diſtant from
the confines which diſtinguiſh the parts of the Moon illuminated,
from the obſcure: you ſhall ſee the ſame term and confine, not
equally diftended, as it would be if the Ball were poliſh'd, but
craggie and rugged. You ſhall ſee beyond the ſame term, in the
dark parts of the Moon many bright prominencies, and diſtinct
from the reſt of the illuminations: you ſhall ſee the ſhadows
foreſaid, according as the illumination gradually riſeth, to
niſh by degrees, till they wholly diſappear; nor are there any of
them to be ſeen when the whole Hemiſphere is enlightned.
gain on the contrary, in the lights paſſage towards the other
miſphere of the Moon, you ſhall again obſerve the ſame
cies that were marked, and you ſhall ſee the projections of their
ſhadows to be made a contrary way, and to decreaſe by degrees:
of which things, once more I ſay, you cannot ſhew me ſo much as
one in yours that are opacous and perſpicuous.
The apparent
evenneſſes of the
Moon cannot be
mitated by way of
more and leſs
city & perſpicuity.
The various
ſpects of the Moon,
imitable with any
opacous matter.
Various appear
ces from which the
Moons montuoſity
is argued.
SAGR. One of them certainly he may imitate, namely, that of
the Full-Moon, when by reaſon of its being all illuminated, there
is not to be ſeen either ſhadow, or other thing, which receiveth
any alteration from its eminencies and cavities. But I beſeech
you, Salviatus, let us ſpend no more time on this Argument, for
a perſon that hath had but the patience to make obſervation of but
one or two Lunations, and is not ſatisfied with this moſt ſenſible
truth, may well be adjudged void of all judgment; and upon
1ſuch why ſhould we throw away our time and breath in vain?
SIMPI. I muſt confeſs I have not made the obſervations, for
that I never had ſo much curioſity, or the Inſtruments proper for
the buſineſs; but I will not fail to do it. In the mean time, we
may leave this queſtion in ſuſpenſe, and paſs to that point which
follows, producing the motives inducing you to think that the
Earth may reflect the light of the Sun no leſs forceably than the
Moon, for it ſeems to me ſo obſcure and opacous, that I judg ſuch
an effect altogether impoſſible.
SALV. The cauſe for which you repute the Earth unapt for
illumination, may rather evince the contrary: And would it not
be ſtrange, Simplicius, if I ſhould apprehend your diſcourſes
ter than you your ſelf?
SIMPL. Whether I argue well or ill, it may be, that you may
better underſtand the ſame than I; but be it ill or well that I
diſcourſe, I ſhall never believe that you can penetrate what I mean
better than I my ſelf.
SALV. Well, I will make you believe the ſame preſently. Tell
me a little, when the Moon is near the Full, ſo that it may be ſeen
by day, and alſo at midnight, at what do you think it more
did, by day or by night?
SIMPL. By night, without all compariſon. And methinks

the Moon reſembleth that pillar of Clouds and pillar of Fire,
which guided the Iſraelites; which at the preſence of the Sun,
appeared like a Cloud, but in the night was very glorious. Thus

I have by day obſerved the Moon amidſt certain ſmall Clouds,
juſt as if one of them had been coloured white, but by night it
ſhines with much ſplendor.
The Moon
pears brighter by
night than by day.
The Moon
held in the day
time, is like to a
little cloud.
SALV. So that if you had never happened to ſee the Moon,
ſave onely in the day time, you would not have thought it more
ſhining than one of thoſe Clouds.
SIMPL. I verily believe I ſhould not.
SALV. Tell me now; do you believe that the Moon is really
more ſhining in the night than day, or that by ſome accident it
ſeemeth ſo?
SIMPL. I am of opinion, that it reſplends in it ſelf as much in
the day as night, but that its light appears greater by night,
cauſe we behold it in the dark mantle of Heaven; and in the day
time, the whole Atmoſphere being very clear, ſo that ſhe little
exceedeth it in luſtre, ſhe ſeems to us much leſs bright.
SALV. Now tell me; have you ever at midnight ſeen the
reſtrial Globe illuminated by the Sun?
SIMPL. This ſeemeth to me a queſtion not to be ask'd, unleſs
in jeſt, or of ſome perſon known to be altogether void of ſenſe.
SALV. No, no; I eſteem you to be a very rational man, and
1do ask the queſtion ſeriouſly; and therefore anſwer me: and if
afterwards you ſhall think that I ſpeak impertinently, I will be
content to be the ſenſeleſs man: for he is much more a fool who
interrogates ſimply, than he to whom the queſtion is put.
SIMPL. If then you do not think me altogether ſimple, take
it for granted that I have anſwered you already, and ſaid, that it
is impoſſible, that one that is upon the Earth, as we are, ſhould ſee
by night that part of the Earth where it is day, namely, that is
luminated by the Sun.
SALV. Therefore you have never ſeen the Earth enlightned,
ſave onely by day; but you ſee the Moon to ſhine alſo in the
dead of night. And this is the cauſe, Simplicius, which makes
you believe that the Earth doth not ſhine like the Moon; but if
you could ſee the Earth illuminated, whilſt you were in ſome dark
place, like our night, you would ſee it ſhine brighter than the
Moon. Now if you deſire that the compariſon may proceed
well, you muſt compare the light of the Earth, with that of the
Moon ſeen in the day time, and not with the ſame by night: for
it is not in our power to ſee the Earth illuminated, ſave onely in
the day. Is it not ſo?
SIMPL. So it ought to be.
SALV. And foraſmuch as you your ſelf have already confeſſed
to have ſeen the Moon by day among ſome little white Clouds,
and very nearly, as to its aſpect, reſembling one of them; you did

thereby grant, that thoſe Clouds, which yet are Elementary
matters, are as apt to receive illumination, as the Moon, yea
more, if you will but call to mind that you have ſometimes ſeen
ſome Clouds of vaſt greatneſs, and as perfect white as the Snow;
and there is no queſtion, but that if ſuch a Cloud could be
tinued ſo luminous in the deep of night, it would illuminate the
places near about it, more than an hundred Moons. If therefore
we were aſſured that the Earth is illuminated by the Sun, like one
of thoſe Clouds, it would be undubitable, but that it would be no
leſs ſhining than the Moon. But of this there is no queſtion to
be made, in regard we ſee thoſe very Clouds in the abſence of
the Sun, to remain by night, as obſcure as the Earth: and that
which is more, there is not any one of us, but hath ſeen many
times ſome ſuch Clouds low, and far off, and queſtioned whether
they were Clouds or Mountains: an evident ſign that the
tains are no leſs luminous than thoſe
Clouds are no leſs
apt than the Moon
to be illuminated
by the Sun.
A wall
ted by the Sun,
compared to the
Moon ſhineth no
leſs than it.
SAGR. But what needs more diſcourſe? See yonder the Moon
is riſen, and more than half of it illuminated; ſee there that wall,
on which the Sun ſhineth; retire a little this way, ſo that you ſee
the Moon ſideways with the wall: look now; which of them
ſhews more lucid? Do not you ſee, that if there is any advantage,
1the wall hath it? The Sun ſhineth on that wall; from thence it

is reverberated upon the wall of the Hall, from thence it's
cted upon that chamber, ſo that it falls on it at the third reflection:
and I am very certain, that there is in that place more light, than
if the Moons light had directly faln upon it.
The third
ction of a Wall
minates more than
the firſt of the
Moon.
SIMPL. But this I cannot believe; for the illumination of the
Moon, eſpecially when it is at the full, is very great.
SAGR. It ſeemeth great by reaſon of the circumjacent dark

places; but abſolutely it is not much, and is leſs than that of the
twilight half an hour after the Sun is ſet; which is manifeſt,
cauſe you ſee not the ſhadows of the bodies illuminated by the
Moon till then, to begin to be diſtinguiſhed on the Earth.
ther, again, that third reflection upon that chamber, illuminates
more than the firſt of the Moon, may be known by going thether,
and reading a Book, and afterwards ſtanding there in the night
by the Moons light, which will ſhew by which of them lights one
may read more or leſs plainly, but I believe without further tryal,
that one ſhould ſee leſs diſtinctly by this later.
The light of the
Moon weaker than
that of the
light.
SALV. Now, Simplicius, (if haply you be ſatisfied) you may
conceive, as you your ſelf know very well, that the Earth doth
ſhine no leſs than the Moon; and the only remembring you of ſome
things, which you knew of your ſelf, and learn'd not of me, hath
aſſured you thereof: for I taught you not that the Moon ſhews
lighter by night than by day, but you underſtood it of your ſelf;
as alſo you could tell me that a little Cloud appeareth as lucid as
the Moon: you knew alſo, that the illumination of the Earth
not be ſeen by night; and in a word, you knew all this, without
knowing that you knew it. So that you have no reaſon to be
pulous of granting, that the dark part of the Earth may illuminate
the dark part of the Moon, with no leſs a light than that
with the Moon illuminates the obſcurities of the night, yea rather
ſo much the greater, inaſmuch as the Earth is forty times bigger
than the Moon.
SIMPL. I muſt confeſs that I did believe, that that ſecondary
light had been the natural light of the Moon.
SALV. And this alſo you know of your ſelf, and perceive not
that you know it. Tell me, do not you know without teaching,
that the Moon ſhews it ſelf more bright by night than by day, in

reſpect of the obſcurity of the ſpace of the ambient? and
quently, do you not know in genere, that every bright body ſhews
the clearer, by how much the ambient is obſcurer?
Luminous bodies
appear the brighter
in an obſcurer
bient.
SIMPL. This I know very well.
SALV. When the Moon is horned, and that ſecondary light
ſeemeth to you very bright, is it not ever nigh the Sun, and
ſequently, in the light of the crepuſculum, (twilight?)
1
SIMPL. It is ſo; and I have oftentimes wiſh'd that the Air
would grow thicker, that I might be able to ſee that ſame light
more plainly; but it ever diſappeared before dark night.
SALV. You know then very certainly, that in the depth of
night, that light would be more conſpicuous.
SIMPL. I do ſo; and alſo more than that, if one could but
take away the great light of the creſcent illuminated by the Sun,
the preſence of which much obſcureth the other leſſer.
SALV. Why, doth it not ſometimes come to paſs, that one may
in a very dark night ſee the whole face of the Moon, without
ing at all illuminated by the Sun?
SIMPL. I know not whether this ever happeneth, ſave onely
in the total Ecclipſes of the Moon.
SALV. Why, at that time this its light would appear very
clear, being in a moſt obſcure medium, and not darkned by the
clarity of the luminous creſcents: but in that poſition, how light
did it appear to you?
SIMPL. I have ſometimes ſeen it of the colour of braſs, and a
little whitiſh; but at other times it hath been ſo obſcure, that I
have wholly loſt the ſight of it.
SALV. How then can that light be ſo natural, which you ſee ſo
cleer in the cloſe of the twilight, notwithſtanding the impediment
of the great and contiguous ſplendor of the creſcents; and which
again, in the more obſcure time of night, all other light removed,
appears not at all?
SIMPL. I have heard of ſome that believed that ſame light to
be participated to theſe creſcents from the other Stars, and in
ticular from Venus, the Moons neighbour.
SALV. And this likewiſe is a vanity; becauſe in the time of
its total obſcuration, it ought to appear more ſhining than ever;
for you cannot ſay, that the ſhadow of the Earth intercepts the
ſight of Venus, or the other Stars. But to ſay true, it is not at
that inſtant wholly deprived thereof, for that the Terreſtrial
miſphere, which in that time looketh towards the Moon, is that
where it is night, that is, an intire privation of the light of the Sun.
And if you but diligently obſerve, you will very ſenſibly perceive,
that like as the Moon, when it is ſharp-horned, doth give very little
light to the Earth; and according as in her the parts
nated by the Suns light do encreaſe: ſo likewiſe the ſplendor to
our ſeeming encreaſeth, which from her is reflected towards us;
thus the Moon, whilſt it is ſharp-forked, and that by being between
the Sun and the Earth, it diſcovereth a very great part of the

reſtrial Hemiſphere illuminated, appeareth very clear: and
ing from the Sun, and paſſing towards the ^{*}Quadrature, you
may ſee the ſaid light by degrees to grow dim; and after the
1Quadrature, the ſame appears very weak, becauſe it continually
loſeth more and more of the view of the luminous part of the
Earth: and yet it ſhould ſucceed quite contrary, if that light were
its own, or communicated to it from the Stars; for then we ſhould
ſee it in the depth of night, and in ſo very dark an ambient.
*By the Moons two
Quadratures you
are to underſtand
its firſt and last
quarters, as
ſtrologers call them
SIMPL. Stay a little; for I juſt now remember, that I have
read in a little modern tract, full of many novelties; “That this
ſecondary light is not derived from the Stars, nor innate in the
Moon, and leaſt of all communicated by the Earth, but that it is

received from the ſame illumination of the Sun, which, the
ſtance of the Lunar Globe being ſomewhat tranſparent,
trateth thorow all its body; but more livelily illuminateth the
ſuperficies of the Hemiſphere expoſed to the rays of the Sun:
and its proſundity imbuing, and (as I may ſay) ſwallowing that
light, after the manner of a cloud or chryſtal, tranſmits it, and
renders it viſibly lucid. And this (if I remember aright) he
proveth by Authority, Experience and Reaſon; citing Cleomedes,
Vitellion, Macrobius, and a certain other modern Author: and
adding, That it is ſeen by experience to ſhine moſt in the days
neareſt the Conjunction, that is, when it is horned, and is chiefly
bright about its limb. And he farther writes, That in the Solar
Ecclipſes, when it is under the Diſcus of the Sun, it may be ſeen
tranſlucid, and more eſpecially towards its utmoſt Circle. And
in the next place, for Arguments, as I think, he ſaith, That it not
being able to derive that light either from the Earth, or from the
Stars, or from it ſelf, it neceſſarily follows, that it cometh from
the Sun. Beſides that, if you do but grant this ſuppoſition, one
may eaſily give convenient reaſons for all the particulars that
occur. For the reaſon why that ſecundary light ſhews more
lively towards the outmoſt limb, is, the ſhortneſs of the ſpace
that the Suns rays hath to penetrate, in regard that of the lines
which paſs through a circle, the greateſt is that which paſſeth
through the centre, and of the reſt, thoſe which are fartheſt from
it, are always leſs than thoſe that are nearer. From the ſame
principle, he ſaith, may be ſhewn why the ſaid light doth not
much diminiſh. And laſtly, by this way the cauſe is aſſigned
whence it comes, that that ſame more ſhining circle about the
utmoſt edge of the Moon, is ſeen at the time of the Solar
clipſe, in that part which lyeth juſt under the Diſcus of the Sun,
but not in that which is beſide the Diſcus: which happeneth
becauſe the rays of the Sun paſs directly to our eye, through the
parts of the Moon underneath: but as for the parts which are
beſides it, they fall beſides the eye.”
The ſecondary
light of the Moon
cauſed by the Sun,
according to ſome.
SALV. If this Philoſopher had been the firſt Author of this
pinion, I would not wonder that he ſhould be ſo affectionate to it,
1as to have received it for truth; but borrowing it from others, I
cannot find any reaſon ſufficient to excuſe him for not perceiving
its fallacies; and eſpecially after he had heard the true cauſe of
that effect, and had it in his power to ſatisfie himſelf by a thouſand
experiments, and manifeſt circumſtances, that the ſame proceeded
from the reflection of the Earth, and from nothing elſe: and the more
this ſpeculation makes ſomething to be deſired, in the judgment of
this Author, and of all thoſe who give no credit to it: ſo much the
more doth their not having underſtood and remembred it, excuſe
thoſe more receſs Antients, who, I am very certain, did they now
underſtand it, would without the leaſt repugnance admit thereof.
And if I may freely tell you what I think, I cannot believe but
that this Modern doth in his heart believe it; but I rather think,
that the conceit he ſhould not be the firſt Author thereof, did a
little move him to endeavour to ſuppreſſe it, or to diſparage it at
leaſt amongſt the ſimple, whoſe number we know to be very
great; and many there are, who much more affect the
rous applauds of the people, than the approbation of a few not
vulgar judgments.
SAGR. Hold good Salviatus, for me thinks, I ſee that you
go not the way to hit the true mark in this your diſcourſe, for theſe
that ^{*} confound all propriety, know alſo how to make themſelves

Authors of others inventions, provided they be not ſo ſtale,
and publick in the Schools and Market-places, as that they are more
then notorious to every one.
* Tendono le
te al commune.
SALV. Ha! well aimed, you blame me for roving from the
point in hand; but what have you to do with Schools and

kets? Is it not all one whether opinions and inventions be new to
men, or the men new to them? If you ^{*} contend about the
ſteem of the Founders of Sciences, which in all times do ſtart up,

you may make your ſelf their inventor, even to the Alphabet it
ſelf, and ſo gain admiration amongſt that illiterate rabble; and
though in proceſſe of time your craft ſhould be perceived, that
would but little prejudice your deſigne; for that others would
ſucceed them in maintaining the number of your fautors; but let
us return to prove to Simplicius the invalidity of the reaſons of his
modern Author, in which there are ſeveral falſities,

cies, and incredible Paradoxes. And firſt, it is falſe that this
condary light is clearer about the utmoſt limb than in the middle
parts, ſo as to form, as it were, a ring or circle more bright than
the reſt of its ſpace or contence. True it is, indeed, that looking
on the Moon at the time of twilight, at firſt ſight there is the
ſemblance of ſuch a circle, but by an illuſion ariſing from the
verſity of confines that bound the Moons Diſcus, which are
fuſed by means of this ſecondary light; foraſmuch as on the part
1towards the Sun it is bounded by the lucid horns of the Moon,
and on the other part, its confining term is the obſcure tract of the
twilight; whoſe relation makes us think the candor of the Moons
Diſcus to be ſo much the clearer; the which happens to be
fuſcated in the oppoſite part, by the greater clarity of the
cents; but if this modern Author had eſſaied to make an

poſition between the eye and the primary ſplendor, by the ridg of
ſome houſe, or ſome other ſcreen, ſo as to have left viſible only
the groſe of the Moon, the horns excluded, he might have ſeen
it all alike luminous.
Its all one
ther opinions be
new to men, or men
new to opinions.
* Conteſtare falſly
rendered in the
Latine Tranſlation
content are.
The ſecondary
light of the Moon
appears in form of
a Ring, that is to
ſay, bright in the
extreme
rence, and not in
the midſt, and why.
The may to
ſerve the
ry light of the
Moon.
SIMPL, I think, now I remember, that he writes of his
making uſe of ſuch another Artifice, to hide from us the falſe
Incidum.
SALV. Oh! how is this (as I believed) inadvertency of his,
changed into a lie, bordering on raſhneſſe; for that every one
may frequently make proof of the contrary. That in the next

place, at the Suns Eclipſe, the Moons Diſcus is ſeen otherwayes
than by privation, I much doubt, and ſpecially when the
clipſe is not total, as thoſe muſt neceſſarily have been, which
were obſerved by the Author; but if alſo he ſhould have
red ſomewhat of light, this contradicts not, rather favoureth our
opinion; for that at ſuch a time, the whole Terreſtrial
ſphere illuminated by the Sun, is oppoſite to the Moon, ſo that
although the Moons ſhadow doth obſcure a part thereof, yet this
is very ſmall in compariſon of that which remains illuminated.
That which he farther adds, that in this caſe, the part of the
limb, lying under the Sun, doth appear very lucid, but that
which lyeth beſides it, not ſo; and that to proceed from the
ming of the ſolar rayes directly through that part to the eye, but
not through this, is really one of thoſe fopperies, which diſco
ver the other fictions, of him which relates them: For if it be
requiſite to the making a ſecondary light viſible in the lunar
cus, that the rayes of the Sun came directly through it to our
eyes, doth not this pitiful Philoſopher perceive, that we ſhould
ver ſee this ſame ſecondary light, ſave onely at the Eclipſe of the
Sun? And if a part onely of the Moon, far leſſe than half a
gree, by being remote from the Suns Diſcus, can deflect or
viate the rayes of the Sun, ſo that they arrive not at our eye;
what ſhall it do when it is diſtant twenty or thirty degrees, as it is
at its firſt apparition? and what courſe ſhall the rayes of the Sun
keep, which are to paſſe thorow the body of the Moon, that

they may find out our eye? This man doth go ſucceſſively
dering what things ought to be, that they may ſerve his purpoſe,
but doth not gradually proceed, accommodating his conceits to
the things, as really they are. As for inſtance, to make the light
1of the Sun capable to penetrate the ſubſtance of the Moon, he
makes her in part diaphanous, as is v. g. the tranſparence of a cloud,
or cryſtal: but I know not what he would think of ſuch a
ſparency, in caſe the ſolar rayes were to paſſe a depth of clouds
of above two thouſand miles; but let it be ſuppoſed that he
ſhould boldly anſwer, that might well be in the Cœleſtial, which
are quite other things from theſe our Elementary, impure, and
feculent bodies; and let us convict his error by ſuch wayes, as
admit him no reply, or (to ſay better) ſubter-fuge. If he will
maintain, that the ſubſtance of the Moon is diaphanous, he
muſt ſay that it is ſo, whileſt that the rayes of the Sun are to
netrate its whole profundity, that is, more than two thouſand
miles; but that if you oppoſe unto them onely one mile, or
leſſe, they ſhould no more penetrate that, than they penetrate
one of our mountains.
The Moons
cus in a ſolar
clipſe can be ſeen
onely by privation.
The Author of the
Book of
ons, accommodates
the things to his
purpoſes, and not
his purpoſes to the
things.
SAGR. You put me in mind of a man, who would have ſold

me a ſecret how to correſpond, by means of a certain ſympathy of
magnetick needles, with one, that ſhould be two or three
ſand miles diſtant; and I telling him, that I would willingly buy
the ſame, but that I deſired firſt to ſee the experiment thereof,
and that it did ſuffice me to make it, I being in one Chamber, and
he in the next, he anſwered me, that in ſo ſmall a diſtance one
could not ſo well perceive the operation; whereupon I turn'd him
going, telling him, that I had no mind, at that time, to take a
journey unto Grand Cairo, or to Muſcovy, to make the
ment; but that, if he would go himſelf, I would perform the
other part, ſtaying in Venice. But let us hear whither the
ction of our Author tendeth, and what neceſſity there is, that he
muſt grant the matter of the Moon to be moſt perforable by the
rayes of the Sun, in a depth of two thouſand miles, but more
opacous than one of our mountains, in a thickneſſe of one mile
onely.
A jeſt put upon one
that would ſell a
certain ſecret for
holding
dency with a perſon
a thouſand miles
off
SALV. The very mountains of the Moon themſelves are a
proof thereof, which percuſſed on one ſide of the Sun, do caſt
on the contrary ſide very dark ſhadows, terminate, and more
ſtinct by much, than the ſhadows of ours; but had theſe
tains been diaphanous, we could never have come to the
ledg of any unevenneſſe in the ſuperficies of the Moon, nor have
ſeen thoſe luminous montuoſities diſtinguiſhed by the terms which
ſeparate the lucid parts from the dark: much leſſe, ſhould we ſee
this ſame term ſo diſtinct, if it were true, that the Suns light did
penetrate the whole thickneſſe of the Moon; yea rather,
ing to the Authors own words, we ſhould of neceſſity diſcern the
paſſage, and confine, between the part of the Sun ſeen, and the
part not ſeen, to be very confuſed, and mixt with light and
1darkneſſe; for that that matter which admits the paſſage of the
Suns rayes thorow a ſpace of two thouſand miles, muſt needs be
ſo tranſparent, that it would very weakly reſiſt them in a
dredth, or leſſer part of that thickneſſe; nevertheleſſe, the term
which ſeparateth the part illuminated from the obſcure, is
dent, and as diſtinct, as white is diſtinct from black; and
ſpecially where the Section paſſeth through the part of the Moon,
that is naturally more clear and montanous; but where the old
ſpots do part, which are certain plains, that by means of their
ſpherical inclination, receive the rayes of the Sun obliquely,
there the term is not ſo diſtinct, by reaſon of the more dimme
lumination. That, laſtly, which he ſaith, how that the ſecondary
light doth not diminiſh and languiſh, according as the Moon
creaſeth, but conſerveth it ſelf continually in the ſame efficacy;
is moſt falſe; nay it is hardly ſeen in the quadrature, when, on
the contrary, it ſhould appear more ſplendid, and be viſible after
the crepuſculum in the dark of night. Let us conclude therefore,
that the Earths reflection is very ſtrong upon the Moon; and that,
which you ought more to eſteem, we may deduce from thence
other admirable congruity between the Moon and Earth;

ly, that if it be true, the Planets operate upon the Earth by their
motion and light, the Earth may probably be no leſſe potent in
operating reciprocally upon them with the ſame light, and
venture, motion alſo. And though it ſhould not move, yet may
it retain the ſame operation; becauſe, as it hath been proved
ready, the action of the light is the ſelf ſame, I mean of the light
of the Sun reflected; and motion doth nothing, ſave only vary
the aſpects, which fall out in the ſame manner, whether we make
the Earth move, and the Sun ſtand ſtill, or the contrary.
The Earth may
ciprocally operate
upon Cœleſtial
dies, with its light.
SIMPL. None of the Philoſophers are found to have ſaid, that
theſe inferiour bodies operate on the Cœleſtial, nay, Ariſtotle
firmes the direct contrary.
SALV. Aristotle and the reſt, who knew not that the Earth and
Moon mutually illuminated each other, are to be excuſed; but
they would juſtly deſerve our cenſure, if whileſt they deſire that
we ſhould grant and believe with them, that the Moon operateth
upon the Earth with light, they ſhould deny to us, who have
taught them that the Earth illuminates the Moon, the operation
the Earth hath on the Moon.
SIMPL. In ſhort, I find in my ſelf a great unwillingneſſe to
admit this commerce, which you would perſwade me to be
twixt the Earth and Moon, placing it, as we ſay, amongſt the
number of the Stars; for if there were nothing elſe, the great
ſeparation and diſtance between it and the Cœleſtial bodies, doth
in my opinion neceſſarily conclude a vaſt diſparity between them.
1
SALV. See Simplicius what an inveterate affection and
ted opinion can do, ſince it is ſo powerful, that it makes you think
that thoſe very things favour you, which you produce againſt
your ſelf. For if ſeparation and diſtance are accidents ſufficient to
perſwade with you a great diverſity of natures, it mnſt follow that

proximity and contiguity import ſimilitude. Now how much more
neerer is the Moon to the Earth, than to any other of the Cœleſtial
Orbs? You muſt acknowledg therefore, according to your own
ceſſion (and you ſhall have other Philoſophers bear you company)
that there is a very great affinity betwixt the Earth and Moon.
Now let us proceed, and ſee whether any thing remains to be
ſidered, touching thoſe objections which you made againſt the
ſemblances that are between theſe two bodies.
Affinity between
he Earth & Moon
in reſpect of their
vicinity.
SIMPL. It reſts, that we ſay ſomething touching the ſolidity of
the Moon, which I argued from its being exquiſite ſmooth and
polite, and you from its montuoſity. There is another ſcruple
ſo comes into my mind, from an opinion which I have, that the
Seas reflection ought by the equality of its ſurface, to be rendered
ſtronger than that of the Earth, whoſe ſuperficies is ſo rough and
opacous.
SALV. As to the firſt objection; I ſay, that like as among the
parts of the Earth, which all by their gravity ſtrive to approach the

neareſt they can poſſible to the center, ſome of them alwayes are
more remote from it than the reſt, as the mountains more than
the valleys, and that by reaſon of their ſolidity and firmneſſe
(for if they were of fluid, they would be even) ſo the ſeeing ſome
parts of the Moon to be elevated above the ſphericity of the
er parts, argueth their hardneſſe; for it is probable that the
ter of the Moon is reduced into a ſpherical form by the
ous conſpiration of all its parts to the ſame ſentenſe. Touching
the ſecond doubt, my thinks that the particulars already obſerved
to happen in the Looking-glaſſes, may very well aſſure us, that the
reflection of light comming from the Sea, is far weaker than that

which cometh from Land; underſtanding it alwayes of the
univerſal reflection; for as to that particular, on which the
ter being calm, caſteth upon a determinate place, there is no
doubt, but that he who ſhall ſtand in that place, ſhall ſee a very
great reflection in the water, but every way elſe he ſhall ſee the
ſurface of the Water more obſcure than that of the Land; and to

prove it to your ſenſes, let us go into yonder Hall, and power
forth a little water upon the Pavement. Tell me now, doth not
this wet brick ſhew more dull than the other dry ones?
leſſe it doth, and will ſo appear, from what place ſoever you
hold it, except one onely, and this is that way which the light
cometh, that entereth in at yonder window; go backwards
therefore by a little and a little.
1
Solidity of the
Lunar Globe
ed from its being
montainous.
The Seas
ction of light much
weaker than that
of the Earth.
An experiment
to prove the
ction of the Water
leſſe clear than
that of the Land.
SIMPL. Here I ſee the weſt part ſhine more than all the reſt of
the pavement, and I ſee that it ſo hapneth, becauſe the
ction of the light which entereth in at the window, cometh
wards me.
SALV. That moiſture hath done no more but filled thoſe little
cavities which are in the brick with water, and reduced its
ficies to an exact eveneſſe; whereupon the reflex rayes iſſue
unitedly towards one and the ſame place; but the reſt of the
pavement which is dry, hath its protuberances, that is, an
merable variety of inclinations in its ſmalleſt particles;
on the reflections of the light ſcatter towards all parts, but more
weakly than if they had gone all united together; and therefore,
the ſame ſheweth almoſt all alike, beheld ſeveral wayes, but far
leſſe clear than the moiſtned brick. I conclude therefore, that the
ſurface of the Sea, beheld from the Moon, in like manner, as it
would appear moſt equal, (the Iſlands and Rocks deducted) ſo it
would ſhew leſſe clear than that of the Earth, which is montanous
and uneven. And but that I would not ſeem, as the ſaying is,
to harp too much on one ſtring, I could tell you that I have
ſerved in the Moon that ſecondary light which I told you came to
her from the reflection of the Terreſtrial Globe, to be notably

more clear two or three dayes before the conjunction, than after,
that is, when we ſee it before break of day in the Eaſt, than
when it is ſeen at night after Sun-ſet in the Weſt; of which
ference the cauſe is, that the Terreſtrial Hemiſphere, which looks
towards the Eaſtern Moon, hath little Sea, and much Land, to
wit, all Aſia, whereas, when it is in the Weſt, it beholds very
great Seas, that is, the whole Atlantick Ocean as far as America:
An Argument ſufficiently probable that the ſurface of the water
appears leſſe ſplendid than that of the Earth.
The ſecondary
light of the Moon
clearer before the
conjunction, than
after.
SIMPL. So that perhaps you believe, thoſe great ſpots
vered in the face of the Moon, to be Seas, and the other clearer
parts to be Land, or ſome ſuch thing?
SALV. This which you ask me, is the beginning of thoſe
congruities which I eſteem to be between the Moon and the
Earth, out of which it is time to diſ-ingage our ſelves, for we
have ſtayed too long in the Moon. I ſay therefore, that if there
were in nature but one way onely, to make two ſuperficies
ted by the Sun, to appear one more clear than the other, and
that this were by the being of the one Earth, and the other
ter; it would be neceſſary to ſay that the ſurface of the Moon
were part earthy and part aquatick; but becauſe we know many
wayes to produce the ſame effect (and others there may be which
we know not of;) therefore I dare not affirm the Moon to
ſiſt of one thing more than another: It hath been ſeen already
1that a ſilver plate boiled, being toucht with the Burniſher,
cometh of white obſcure; that the moiſt part of the Earth ſhews
more obſcure than the dry; that in the tops of Hills, the woody
parts appear more gloomy than the naked and barren; which
hapneth becauſe there falleth very much ſhadow among the Trees,
but the open places are illuminated all over by the Sun. And this
mixtion of ſhadow hath ſuch operation, that in tuſted velvet, the
ſilk which is cut, is of a far darker colour than that which is not
cut, by means of the ſhadows diffuſed betwixt thred and thred,
and a plain velvet ſhews much blacker than a Taffata, made of the
ſame ſilk. So that if there were in the Moon things which ſhould
look like great Woods, their aſpect might repreſent unto us the
ſpots which we diſcover; alike difference would be occaſioned, if
there were Seas in her: and laſtly, nothing hindreth, but that thoſe
ſpots may really be of an obſcurer colour than the reſt; for thus
the ſnow makes the mountains ſhew brighter. That which is

ly obſerved in the Moon is, that its moſt obſcure parts are all
plains, with few riſes and bancks in them; though ſome there be;
the reſt which is of a brighter colour, is all full of rocks,
tains, hillocks of ſpherical and other figures; and in particular, round
about the ſpots are very great ledges of mountains. That the

ſpots be plain ſuperficies, we have aſſuredproof, in that we ſee,
how that the term which diſtinguiſheth the part illuminated from
the obſcure, in croſſing the ſpots makes the interſection even, but
in the clear parts it ſhews all craggy and ſhagged. But I know not
as yet whether this evenneſſe of ſuperficies may be ſufficient of it
ſelf alone, to make the obſcurity appear, and I rather think not.
Beſides, I account the Moon exceeding different from the Earth;
for although I imagine to my ſelf that thoſe are not idle and dead
Regions, yet I affirm not, that there are in them motion and life,

much leſs that there are bred plants, animals or other things like
to ours; but, if ſuch there be, they ſhould nevertheleſs be very
different, and remote from our imagination. And I am induced ſo
to think, becauſe in the firſt place, I eſteem that the matter of the
Lunar Globe conſiſts not of Earth and Water; and this alone
ſufficeth to take away the generations and alterations reſembling
ours: but now ſuppoſing that there were in the Moon, Water and

Earth, yet would they not produce plants and animals like to
ours; and this for two principal reaſons: The firſt is, that unto our

productions there are required ſo many variable aſpects of the Sun,
that without them they would all miſcarry: now the habitudes of
the Sun towards the Earth are far different from thoſe towards
the Moon. We as to the diurnal illumination, have, in the greater
part of the Earth, every twenty four hours part day, and part
night, which effect in the Moon is monethly: and that annual
1nation and elevation of the Sun in the Zodiack, by which it

duceth diverſity of Seaſons, and inequality of dayes and nights,
are finiſhed in the Moon in a moneth; and whereas the Sun to us

riſeth and declineth ſo much, that from the greateſt to the leaſt
titude, there is a difference of almoſt 47 degrees, for ſo much is
the diſtance from one to the other Tropick; this is in the Moon
but ten degrees only, or little more; namely, as much as the
teſt Latitudes of the Dragon on each ſide the Ecliptick. Now
conſider what effect the Sun would have in the torrid Zone, ſhould
it continually for fifteen dayes together beam forth its Rayes upon
it; which without all queſtion would deſtroy plants, herbs,
and living creatures: and if it ſhould chance that there were any
production, it would be of herbs, plants, and creatures very

rent from thoſe which are now there. Secondly, I verily believe
that in the Moon there are no rains, for if Clouds ſhould gather
in any part thereof, as they do about the Earth, they would
upon hide from our ſight ſome of thoſe things, which we with the
Teleſcope behold in the Moon, and in a word, would ſome way or
other change its Phœnomenon, an effect which I could never by long
and diligent obſervations diſcover; but alwayes beheld it in a
even and pure ſerenity.
The obſcurer
parts of the Moon
are plains, and the
more bright
tainous.
Long ledges of
mountaixs about
the ſpots of the
Moon.
There are not
generated in the
Moon things like
to ours, but if
there be any
ductions, they are
very different.
The Moon not
compoſed of Water
and Earth.
Thoſe aſpects of
the Sun neceſſary
for our
ons, are not ſo in
the Moon.
Natural dayas
in the Moon are of
a Moneth long.
To the Moon
the Sun aſeondeth
and declineth with
a difference of ten
degrees, and to the
Earth of forty
ven degrees.
There are no
rains in the Moon.
SAGR. To this may be anſwered, either that there might be
great miſts, or that it might rain in the time of their night, that is,
when the Sun doth not illuminate it.
SALV. If other paſſages did but aſſure us, that there were
nerations in it like to ours, and that there was onely wanting the
concourſe of rains, we might find out this, or ſome other
rament to ſerve inſtead thereof, as it happens in Egypt by the
undation of Nile: but not meeting with any accident, which
reſponds with ours, of many that have been ſought out for the
duction of the like effects, we need not trouble our ſelves to
duce one alone; and that alſo, not becauſe we have certain
vation of it, but for a bare non-repugnance that we find therein.
Moreover, if I was demanded what my firſt apprehenſion, and pure
natural reaſon dictated to me concerning the production of things
like or unlike there above, I would alwayes reply, that they are
moſt different, and to us altogether unimaginable, for ſo me thinks
the riches of Nature, and the omnipotence of our Creator and
Governour, do require.
SAGR. I ever accounted extraordinary madneſſe that of thoſe,
who would make humane comprehenſion the meaſure of what
ture hath a power or knowledge to effect; whereas on the

trary there is not any the leaſt effect in Nature, which can be fully
underſtood by the moſt ſpeculative wits in the world. This their
ſo vain preſumption of knowing all, can take beginning from
1thing, unleſſe from their never having known any thing; for if
one hath but once onely experienced the perfect knowledg of one
onely thing, and but truly taſted what it is to know, he ſhall
ceive that of infinite other concluſions, he underſtands not ſo much
as one.
The having a
perfect knowledg
of nothing, maketh
ſome believe they
underſtand all
things.
SALV. Your diſcourſe is very concluding; in confirmation of
which we have the example of thoſe who underſtand, or have
known ſome thing, which the more knowing they are, the more
they know, and freely confeſſe that they know little; nay, the
wiſeſt man in all Greece, and for ſuch pronounced by the Oracle,
openly profeſſed to know that he knew nothing.
SIMPL. It muſt be granted therefore, either that Socrates or
that the Oracle it ſelf was a lyar, that declaring him to be moſt
wiſe, and he confeſſing that he knew himſelf to be moſt
norant.
SALV. Neither one nor the other doth follow, for that both

the aſſertions may be true. The Oracle adjudged Socrates the
ſeſt of all men, whoſe knowledg is limited; Socrates
ledgeth that he knew nothing in relation to abſolute wiſdome,
which is infinite; and becauſe of infinite, much is the ſame part,
as is little, and as is nothing (for to arrive v. g. to the infinite
number, it is all one to accumulate thouſands, tens, or ciphers,)
therefore Socrates well perceived his wiſdom to be nothing, in
compariſon of the infinite knowledg which he wanted. But yet,
becauſe there is ſome knowledg found amongſt men, and this
not equally ſhared to all, Socrates might have a greater ſhare
thereof than others, and therefore verified the anſwer of the
Oracle.
The anſwer of
the Oracle true in
judging Socrates
the wiſeft of his
time.
SAGR. I think I very well underſtand this particular amongſt
men, Simplicius there is a power of operating, but not equally
diſpenſed to all; and it is without queſtion, that the power of an
Emperor is far greater than that of a private perſon; but, both
this and that are nothing in compariſon of the Divine
tence. Amongſt men, there are ſome that better underſtand
Agriculture than many others; but the knowledg of planting a
Vine in a trench, what hath it to do with the knowledg of
king it to ſprout forth, to attract nouriſhment, to ſelect this good
part from that other, for to make thereof leaves, another to make
ſprouts, another to make grapes, another to make raiſins,
ther to make the huskes of them, which are the works of moſt
wiſe Nature? This is one only particular act of the innumerable,
which Nature doth, and in it alone is diſcovered an infinite

dom, ſo that Divine Wiſdom may be concluded to be infinitely
infinite.
Divine Wiſdom
infinitely infinise.
SALV. Take hereof another example. Do we not ſay that the
1judicious diſcovering of a moſt lovely Statua in a piece of Marble,

hath ſublimated the wit of Buonarruotti far above the vulgar wits
of other men? And yet this work is onely the imitation of a
meer aptitude and diſpoſition of exteriour and ſuperficial
bers of an immoveable man; but what is it in compariſon of a
man made by nature, compoſed of as many exteriour and
riour members, of ſo many muſcles, tendons, nerves, bones,
which ſerve to ſo many and ſundry motions? but what ſhall we
ſay of the ſenſes, and of the powers of the ſoul, and laſtly, of
the underſtanding? May we not ſay, and that with reaſon, that
the ſtructure of a Statue fals far ſhort of the formation of a living
man, yea more of a contemptible worm?
Buonarruotti, a
ſtatuary of
rable ingenuity.
SAGR. And what difference think you, was there betwixt the
Dove of Architas, and one made by Nature?
SIMPL. Either I am none of theſe knowing men, or elſe
there is a manifeſt contradiction in this your diſcourſe. You
count underſtanding amongſt the greateſt (if you make it not the
chief of the) Encomiums aſcribed to man made by Nature, and
a little before you ſaid with Socrates, that he had no knowledg at
all; therefore you muſt ſay, that neither did Nature underſtand
how to make an underſtanding that underſtandeth.
SALV. You argue very cunningly, but to reply to your
ction I muſt have recourſe to a Philoſophical diſtinction, and ſay
that the underſtanding is to be taken too ways, that is intenſivè, or

extenſivè; and that extenſive, that is, as to the multitude of
ligibles, which are infinite, the underſtanding of man is as
thing, though he ſhould underſtand a thouſand propoſitions; for
that a thouſand, in reſpect of infinity is but as a cypher: but taking
the underſtanding intenſive, (in as much as that term imports)
tenſively, that is, perfectly ſome propoſitions, I ſay, that humane
dom underſtandeth ſome propoſitions ſo perfectly, and is as
lutely certain thereof, as Nature her ſelf; and ſuch are the pure
Mathematical ſciences, to wit, Geometry and Arithmetick: in which
Divine Wiſdom knows infinite more propoſitions, becauſe it knows
them all; but I believe that the knowledge of thoſe few
hended by humane underſtanding, equalleth the divine, as to the
certainty objectivè, for that it arriveth to comprehend the
ſity thereof, than which there can be no greater certainty.
Man
eth very well
tenſivè, but little
extenſivè.
SIMPL. This ſeemeth to me a very bold and raſh expreſſion.
SALV. Theſe are common notions, and far from all umbrage
of temerity, or boldneſs, and detract not in the leaſt from the
jeſty of divine wiſdom; as it nothing diminiſheth the omnipotence
thereof to ſay, that God cannot make what is once done, to be
done: but I doubt, Simplicius, that your ſcruple ariſeth from an
pinion you have, that my words are ſomewhat equivocal;
1fore the better to expreſs my ſelf I ſay, that as to the truth, of
which Mathematical demonſtrations give us the knowledge, it is
the ſame, which the divine wiſdom knoweth; but this I muſt grant
you, that the manner whereby God knoweth the infinite

ſitions, of which we underſtand ſome few, is highly more excellent
than ours, which proceedeth by ratiocination, and paſſeth from

cluſion to concluſion, whereas his is done at one ſingle thought or
intuition; and whereas we, for example, to attain the knowledg
of ſome paſſion of the Circle, which hath infinite, beginning
from one of the moſt ſimple, and taking that for its definition,
do proceed with argumentation to another, and from that to a
third, and then to a fourth, &c. the Divine Wiſdom, by the
apprehenſion of its eſſence comprehends, without temporary
ocination, all theſe infinite paſſions; which notwithſtanding, are
in effect virtually compriſed in the definitions of all things; and, to

conclude, as being infinite, perhaps are but one alone in their nature,
and in the Divine Mind; the which neither is wholly unknown to
humane underſtanding, but onely be-clouded with thick and

groſſe miſts; which come in part to be diſſipated and clarified,
when we are made Maſters of any concluſions, firmly
ſtrated, and ſo perfectly made ours, as that we can ſpeedily run
through them; for in ſum, what other, is that propoſition, that
the ſquare of the ſide ſubtending the right angle in any triangle,
is equal to the ſquares of the other two, which include it, but
onely the Paralellograms being upon common baſes, and between
parallels equal amongſt themſelves? and this, laſtly, is it not the
ſame, as to ſay that thoſe two ſuperficies are equal, of which
equal parts applyed to equal parts, poſſeſſe equal place? Now

theſe inferences, which our intellect apprehendeth with time and a
gradual motion, the Divine Wiſdom, like light, penetrateth in
an inſtant, which is the ſame as to ſay, hath them alwayes
ſent: I conclude therefore, that our underſtanding, both as to
the manner and the multitude of the things comprehended by us,
is infinitely ſurpaſt by the Divine Wiſdom; but yet I do not ſo
vilifie it, as to repute it abſolutely nothing; yea rather, when I
conſider how many and how great miſteries men have underſtood,
diſcovered, and contrived, I very plainly know and underſtand
the mind of man to be one of the works, yea one of the moſt
cellent works of God.
Gods manner of
knowing different
from that of men.
Humane
ſtanding done by
raciocination.
Definitions
tein virtually all
the paſſions of the
things defined.
Infinite Paſſions
are perhaps but
one onely.
The diſcourſes
which humane
reaſon makes in a
certain time, the
Divine Wiſdom
ſolveth in a
ment; that is, hath
them alwayes
ſent.
SAGR. I have oft times conſidered with my ſelf, in purſuance

of that which you ſpeak of, how great the wit of man is; and
whil'ſt I run thorow ſuch and ſo many admirable inventions found
out by him, as well in the Arts, as Sciences; and again reflecting
upon my own wit, ſo far from promiſing me the diſcovery of any
thing new, that I deſpair of comprehending what is already
1covered, confounded with wonder, and ſurpriſed with
tion, I account my ſelf little leſſe than miſerable. If I behold a
Statue of ſome excellent Maſter, I ſay with my ſelf; When wilt
thou know how to chizzle away the refuſe of a piece of Marble,
and diſcover ſo lovely a figure, as lyeth hid therein? When wilt
thou mix and ſpread ſo many different colours upon a Cloth, or
Wall, and repreſent therewith all viſible objects, like a Michael
Angelo, a Raphaello, or a Tizvano? If I behold what inventions
men have in comparting Muſical intervals, in eſtabliſhing
cepts and Rules for the management thereof with admirable
light to the ear: When ſhall I ceaſe my aſtoniſhment? What
ſhall I ſay of ſuch and ſo various Inſtruments of that Art? The
reading of excellent Poets, with what admiration doth it ſwell
any one that attentively conſidereth the invention of conceits,
and their explanation? What ſhall we ſay of Architecture?

What of Navigation? But, above all other ſtupendious
ons, what ſublimity of mind was that in him, that imagined to
himſelf to find out a way to communicate his moſt ſecret thoughts
to any other perſon, though very far diſtant from him either in
time, or place, ſpeaking with thoſe that are in the India's;
ing to thoſe that are not yet born, nor ſhall be this thouſand, or
ten thouſand years? and with how much facility? but by the

rious collocation of ^{*} twenty little letters upon a paper? Let this
be the Seal of all the admirable inventions of man, and the cloſe
of our Diſcourſe for this day: For the warmer hours being paſt,
I ſuppoſe that Salviatus hath a deſire to go and take the air in his
Gondelo; but too morrow we will both wait upon you, to
tinue the Diſcourſes we have begun, &c.
The wit of man
admirably acute.
The invention of
writing ſtupendious
above all others.
* For of ſo many
only the Italian
Alphabet conſiſts.
11[Figure 1]2[Figure 2]3[Figure 3]4[Figure 4]5[Figure 5]6[Figure 6]7[Figure 7]
Place this Plate
at the end of
the first
Dialogue
1
[Empty page]
1
GALILÆUS
Galilæus Lyncæus,
HIS
SYSTEME
OF THE
WORLD.
The Second Dialogue.
INTERLOCVTORS.
SALVIATUS, SAGREDUS, and SIMPLICIUS.
SALV. The yeſter-dayes diverſions which led us
out of the path of our principal diſcourſe,
were ſuch and ſo many, that I know not
how I can without your aſſiſtance
ver the track in which I am to proceed.
SAGR. I wonder not, that you, who
have your fancy charged and laden with
both what hath been, and is to be
ken, do find your ſelf in ſome
on; but I, who as being onely an Auditor, have nothing to
then my memory withal, but ſuch things as I have heard, may
happily by a ſuccinct rehearſal of them, recover the firſt thred
of our Diſcourſe. As far therefore as my memory ſerves me, the
ſum of yeſterdayes conferences were an examination of the
1ciples of Ptolomy and Copernicus, and which of their opinions is
the more probable and rational; that, which affirmeth the
ſtance of the Cœleſtial bodies to be ingenerable, incorruptible,
alterable, impaſſible, and in a word, exempt from all kind of change,
ſave that of local, and therefore to be a fifth eſſence, quite different
from this of our Elementary bodies, which are generable,
tible, alterable, &c. or elſe the other, which taking away ſuch
deformity from the parts of the World, holdeth the Earth to
joy the ſame perfections as the other integral bodies of the
verſe; and eſteemeth it a moveable and erratick Globe, no leſſe
than the Moon, Jupiter, Venus, or any other Planet: And laſtly,
maketh many particular parallels betwixt the Earth and Moon;
and more with the Moon, than with any other Planet;
ly by reaſon we have greater and more certain notice of it, as
being leſſe diſtant from us. And having, laſtly, concluded this
ſecond opinion to have more of probability with it than the firſt,
I ſhould think it beſt in the ſubſequent diſcourſes to begin to
mine whether the Earth be eſteemed immoveable, as it hath
been till now believed by moſt men, or elſe moveable, as ſome
ancient Philoſophers held, and others of not very receſſe times,
were of opinion; and if it be moveable, to enquire of what
kind its motion may be?
SALV. I ſee already what way I am to take; but before we
offer to proceed any farther, I am to ſay ſomething to you
ing thoſe laſt words which you ſpake, how that the opinion which
holds the Earth to be endued with the ſame conditions that the
Cœleſtial bodies enjoy, ſeems to be more true than the
ry; for that I affirmed no ſuch thing, nor would I have any of the
Propoſitions in controverſie, be made to ſpeak to any definitive
ſenſe: but I onely intended to produce on either part, thoſe
ſons and anſwers, arguments and ſolutions, which have been
therto thought upon by others, together with certain others,
which I have ſtumbled upon in my long ſearching thereinto,
wayes remitting the deciſion thereof to the judgment of others.
SAGR. I was unawares tranſported by my own ſenſe of the
thing; and believing that others ought to judg as I did, I made
that concluſion univerſal, which ſhould have been particular; and
therefore confeſſe I have erred, and the rather, in that I know
not what Simplicius his judgment is in this particular.
SIMPL. I muſt confeſſe, that I have been ruminating all this
night of what paſt yeſterday, and to ſay the truth, I meet
in with many acute, new, aud plauſible notions; yet nevertheleſs,
I find my ſelf over-perſwaded by the authority of ſo many great
Writers, and in particular -------&c. I ſee you ſhake your
head Sagredus, and ſmile to your ſelf, as if I had uttered ſome
great abſurdity.
1
SAGR. I not onely ſmile, but to tell you true, am ready to
burſt with holding in my ſelf from laughing outright, for you
have put me in mind of a very pretty paſſage, that I was a
neſſe of, not many years ſince, together with ſome others of
my worthy friends, which I could yet name unto you.
SALV. It would be well that you told us what it was, that ſo
Simplicius may not ſtill think that he gave you the occaſion of
laughter.
SAGR. I am content. I found one day, at home in his houſe, at
Venice, a famous Phiſician, to whom ſome flockt for their ſtudies,
and others out of curioſity, ſometimes came thither to ſee certain
natomies diſſected by the hand of a no leſſe learned, than careful
and experienced Anatomiſt. It chanced upon that day, when I was

there, that he was in ſearch of the original and riſe of the Nerves,
about which there is a famous controverſie between the Galeniſts
and Peripateticks; and the Anatomiſt ſhewing, how that the great
number of Nerves departing from the Brain, as their root, and
paſſing by the nape of the Neck, diſtend themſelves afterwards
along by the Back-bone, and branch themſelves thorow all the
Body; and that a very ſmall filament, as fine as a thred went to
the Heart; he turned to a Gentleman whom he knew to be a
ripatetick Philoſopher, and for whoſe ſake he had with
dinary exactneſſe, diſcovered and proved every thing, and
ed of him, if he was at length ſatisfied and perſwaded that the
nal of the Nerves proceeded from the Brain, and not from the
Heart? To which the Philoſopher, after he had ſtood muſing a

while, anſwered; you have made me to ſee this buſineſſe ſo
plainly and ſenſibly, that did not the Text of Ariſtotle aſſert the
contrary, which poſitively affirmeth the Nerves to proceed from
the Heart, I ſhould be conſtrained to confeſſe your opinion to be
true.
The original of
the Nerv s.
cording to
tle, and according
to Phiſicians.
The ridiculus
anſwer of a
ſopher,
ning the original of
the Nerves.
SIMPL. I would have you know my Maſters, that this
verſie about the original of the Nerves is not yet ſo proved and
decided, as ſome may perhaps perſwade themſelves.
SAGR. Nor queſtionleſſe ever ſhall it be, if it find ſuch like
contradictors; but that which you ſay, doth not at all leſſen the
extravagance of the anſwer of that Peripatetick, who againſt
ſuch ſenſible experience produced not other experiments, or
ſons of Ariſtotle, but his bare authority and pure ipſe dixit.
SIMPL. Ariſtotle had not gained ſo great authority, but for
the force of his Demonſtrations, and the profoundneſſe of his
arguments; but it is requiſite that we underſtand him, and not
onely underſtand him, but have ſo great familiarity with his
Books, that we form a perfect Idea thereof in our minds, ſo as
that every ſaying of his may be alwayes as it were, preſent in our
1memory for he did not write to the vulgar, nor is he obliged to
ſpin out his Sillogiſmes with the trivial method of diſputes; nay
rather, uſing a freedome, he hath ſometimes placed the proof
of one Propoſition amongſt Texts, which ſeem to treat of quite

another point; and therefore it is requiſite to be maſter of all
that vaſt Idea, and to learn how to connect this paſſage with that,
and to combine this Text with another far remote from it; for it
is not to be queſtioned but that he who hath thus ſtudied him,
knows how to gather from his Books the demonſtrations of every
knowable deduction, for that they contein all things.
Requiſites to fit
a man to
phate well after
the manner of
riſtotle.
SAGR. But good Simplicius, like as the things ſcattered here
and there in Ariſtotle, give you no trouble in collecting them,
but that you perſwade your ſelf to be able by comparing and

connecting ſeveral ſmall ſentences to extract thence the juice of
ſome deſired concluſion, ſo this, which you and other
ous Philoſophers do with the Text of Ariſtotle, I could do by the

verſes of Virgil, or of Ovid, compoſing thereof ^{*} Centones, and
therewith explaining all the affairs of men, and ſecrets of
ture. But what talk I of Virgil, or any other Poet? I have a
tle Book much ſhorter than Ariſtotle and Ovid, in which are
teined all the Sciences, and with very little ſtudy, one may gather
out of it a moſt perfect Idea, and this is the Alphabet; and there
is no doubt but that he who knows how to couple and diſpoſe
aright this and that vowel, with thoſe, or thoſe other conſonants,
may gather thence the infallible anſwers to all doubts, and
duce from them the principles of all Sciences and Arts, juſt in the
ſame manner as the Painter from divers ſimple colours, laid
rally upon his Pallate, proceedeth by mixing a little of this and
a little of that, with a little of a third, to repreſent to the life
men, plants, buildings, birds, fiſhes, and in a word,
ing what ever object is viſible, though there be not on the Pallate
all the while, either eyes, or feathers, or fins, or leaves, or ſtones.
Nay, farther, it is neceſſary, that none of the things to be
ted, or any part of them, be actually among colours, if you
would be able therewith to repreſent all things; for ſhould there
be amongſt them v. gr. feathers, theſe would ſerve to repreſent
nothing ſave birds, and plumed creatures.
A cunning way
to gather
phy out of any book
whatſoever.
* A word
ing works
ſed of many
ments of verſes
collected out of the
Poets.
SALV. And there are certain Gentlemen yet living, and in health,
who were preſent, when a Doctor, that was Profeſſor in a

mous Academy, hearing the deſcription of the Teleſcope, by him
not ſeen as then, ſaid, that the invention was taken from
ſtotle, and cauſing his works to be fetch't, he turned to a place
where the Philoſopher gives the reaſon, whence it commeth, that
from the bottom of a very deep Well, one may ſee the ſtars in
Heaven, at noon day; and, addreſſing himſelf to the company,
1ſee here, ſaith he, the Well, which repreſenteth the Tube, ſee
here the groſs vapours, from whence is taken the invention of
the Cryſtals, and ſee here laſtly the ſight fortified by the paſſage
of the rays through a diaphanous, but more denſe and obſcure
medium.
Invention of the
Teleſcope taken
from Ariſtotle.
SAGR. This is a way to comprehend all things knowable, much
like to that wherewith a piece of marble conteineth in it one, yea,
a thouſand very beautiful Statua's, but the difficulty lieth in
ing able to diſcover them; or we may ſay, that it is like to the
propheſies of Abbot Joachim, or the anſwers of the Heathen
Oracles, which are not to be underſtood, till after the things
fore-told are come to paſſe.
SALV. And why do you not adde the predictions of the
nethliacks, which are with like cleerneſſe ſeen after the event, in
their Horoſcopes, or, if you will, Configurations of the Heavens.
SAGR. In this manner the Chymiſts find, being led by their

melancholly humour, that all the ſublimeſt wits of the World
have writ of nothing elſe in reality, than of the way to make
Gold; but, that they might tranſmit the ſecret to poſterity
out diſcovering it to the vulgar, they contrived ſome one way, and
ſome another how to conceal the ſame under ſeveral maskes; and
it would make one merry to hear their comments upon the ancient
Poets, finding out the important miſteries, which lie hid under
their Fables; and the ſignification of the Loves of the Moon,
and her deſcending to the Earth for Endimion; her diſpleaſure
againſt Acteon, and what was meant by Jupiters turning himſelf
into a ſhowre of Gold; and into flames of fire; and what great
ſecrets of Art are conteined in that Mercury the Interpreter; in
thoſe thefts of Pluto; and in thoſe Branches of Gold.
Chymiſts
pret the Eables of
the Poets to be
crets for making of
Gold.
SIMPL. I believe, and in part know, that there want not in the
World very extravagant heads, the vanities of whom ought not to
redound to the prejudice of Ariſtotle, of whom my thinks you
ſpeak ſometimes with too little reſpect, and the onely antiquity
and bare name that he hath acquired in the opinions of ſo many
famous men, ſhould ſuffice to render him honourable with all
that profeſſe themſelves learned.
SALV. You ſtate not the matter rightly, Simplicius; There
are ſome of his followers that fear before they are in danger,
who give us occaſion, or, to ſay better, would give us cauſe to
eſteem him leſſe, ſhould we conſent to applaud their Capricio's.

And you, pray you tell me, are you for your part ſo ſimple, as
not to know that had Arictotle been preſent, to have heard the
Doctor that would have made him Author of the Teleſcope, he
would have been much more diſpleaſed with him, than with thoſe,
who laught at the Doctor and his Comments? Do you queſtion
1whether Ariſtotle, had he but ſeen the novelties diſcovered in
ven, would not have changed his opinion, amended his Books,
and embraced the more ſenſible Doctrine; rejecting thoſe ſilly
Gulls, which too ſcrupulouſly, go about to defend what ever he
hath ſaid; not conſidering, that if Ariſtotle were ſuch a one as
they fancy him to themſelves, he would be a man of an
ble wit, an obſtinate mind, a barbarous ſoul, a ſtubborn will,
that accounting all men elſe but as ſilly ſheep, would have his
Oracles preferred before the Senſes, Experience, and Nature her
ſelf? They are the Sectators of Aristotle that have given him this
Authority, and not he that hath uſurped or taken it upon him;
and becauſe it is more eaſie for a man to ſculk under anothers
ſhield than to ſhew himſelf openly, they tremble, and are affraid
to ſtir one ſtep from him; and rather than they will admit ſome
alterations in the Heaven of Ariſtotle, they will impertinently
ny thoſe they behold in the Heaven of Nature.
Some of
tles Sectators
pare the reputation
of their Maſter, in
going about to
hanſe it.
SAGR. Theſe kind of Drolleries put me in mind of that

ary which having reduced a great piece of Marble to the Image of
an Hercules, or a thundring Jupiter, I know not whether, and
given it with admirable Art ſuch a vivacity and threatning fury,
that it moved terror in as many as beheld it; he himſelf began
alſo to be affraid thereof, though all its ſprightfulneſſe, and life
was his own workmanſhip; and his affrightment was ſuch, that
he had no longer the courage to affront it with his Chizzels and
Mallet.
A ridiculous
paſſage of a certain
Statuary.
SALV. I have many times wondered how theſe nice
ers of what ever fell from Ariſtotle, are not aware how great a
judice they are to his reputation and credit; and how that the
more they go about to encreaſe his Authority, the more they
diminiſh it; for whileſt I ſee them obſtinate in their attempts
to maintain thoſe Propoſitions which I palpably diſcover to
be manifeſtly falſe; and in their deſires to perſwade me that
ſo to do, is the part of a Philoſopher; and that Ariſtotle himſelf
would do the ſame, it much abates in me of the opinion that he
hath rightly philoſophated about other concluſions, to me more
abſtruſe: for if I could ſee them concede and change opinion in
a manifeſt truth, I would believe, that in thoſe in which they
ſhould perſiſt, they may have ſome ſolid demonſtrations to me
known, and unheard of.
SAGR. Or when they ſhould be made to ſee that they have
zarded too much of their own and Ariſtotle's repuatation in
feſſing, that they had not underſtood this or that concluſion found
out by ſome other man; would it not be a leſs evil for them to
ſeek for it amongſt his Texts, by laying many of them together,
according to the art intimated to us by Simplicius? for if his
1works contain all things knowable, it muſt follow alſo that they
may be therein diſcovered.
SALV. Good Sagredus, make no jeſt of this advice, which me
thinks you rehearſe in too Ironical a way; for it is not long ſince
that a very eminent Philoſopher having compoſed a Book de animà,
wherein, citing the opinion of Ariſtotle, about its being or not
ing immortal, he alledged many Texts, (not any of thoſe
fore quoted by Alexander ab Alexandro: for in thoſe he ſaid, that
Ariſtotle had not ſo much as treated of that matter, much leſs
termined any thing pertaining to the ſame, but others) by himſelf
found out in other more abſtruſe places, which tended to an
roneous ſenſe: and being adviſed, that he would find it an hard
matter to get a Licence from the Inquiſitors, he writ back unto

his friend, that he would notwithſtanding, with all expedition
procure the ſame, for that if no other obſtacle ſhould interpoſe,
he would not much ſcruple to change the Doctrine of Ariſtotle,
and with other expoſitions, and other Texts to maintain the
trary opinion, which yet ſhould be alſo agreeable to the ſenſe of
Ariſtotle.
A brave
tion of a certain
Peripatetick
loſopher.
SAGR. Oh moſt profound Doctor, this! that can command
me that I ſtir not a ſtep from Ariſtotle, but will himſelf lead
him by the noſe, and make him ſpeak as he pleaſeth. See how
much it importeth to learn to take Time by the Fore-top. Nor
is it ſeaſonable to have to do with Hercules, whil'ſt he is
raged, and amongſt the Furies, but when he is telling merry tales
amongſt the Meonion Damoſels. Ah, unheard of ſordidneſſe of

ſervile ſouls! to make themſelves willing ſlaves to other mens
nions; to receive them for inviolable Decrees, to engage
ſelves to ſeem ſatisfied and convinced by arguments, of ſuch
cacy, and ſo manifeſtly concludent, that they themſelves
not certainly reſolve whether they were really writ to that
poſe, or ſerve to prove that aſſumption in hand, or the contrary.
But, which is a greater madneſſe, they are at variance amongſt
themſelves, whether the Author himſelf hath held the affirmative
part, or the negative. What is this, but to make an Oracle of a
Log, and to run to that for anſwers, to fear that, to reverence
and adore that?
The ſervile
rit of ſome of
ſtotles followers.
SIMPL. But in caſe we ſhould recede from Aristotle, who have
we to be our Guid in Philoſophy? Name you ſome Author.
SALV. We need a Guid in unknown and uncouth wayes, but
in champion places, and open plains, the blind only ſtand in need
of a Leader; and for ſuch, it is better that they ſtay at home.
But he that hath eyes in his head, and in his mind, him ſhould
a man chooſe for his Guid. Yet miſtake me not, thinking that I

ſpeak this, for that I am againſt hearing of Ariſtotle; for on the
1contrary, I commend the reading, and diligently ſtudying of him;
and onely blame the ſervile giving ones ſelf up a ſlave unto him,
ſo, as blindly to ſubſcribe to what ever he delivers, and without
ſearch of any farther reaſon thereof, to receive the ſame for an
violable decree. Which is an abuſe, that carrieth with it
ther great inconvenience, to wit, that others will no longer take
pains to underſtand the validity of his Demonſtrations. And
what is more ſhameful, than in the middeſt of publique diſputes,
whileſt one perſon is treating of demonſtrable concluſions, to
hear aother interpoſe with a paſſage of Ariſtotle, and not
dome writ to quite another purpoſe, and with that to ſtop the
mouth of his opponent? But if you will continue to ſtudy in this
manner, I would have you lay aſide the name of Philoſophers;

and call your ſelves either Hiſtorians or Doctors of Memory, for
it is not ſit, that thoſe who never philoſophate, ſhould uſurp
the honourable title of Philoſophers. But it is beſt for us to
turn to ſhore, and not lanch farther into a boundleſſe Gulph, out
of which we ſhall not be able to get before night. Therefore
Simplicius, come either with arguments and demonſtrations of
your own, or of Ariſtotle, and bring us no more Texts and

ked authorities, for our diſputes are about the Senſible World,
and not one of Paper. And foraſmuch as in our diſcourſes
day, we retrein'd the Earth from darkneſſe, and expoſed it to the
open skie, ſhewing, that the attempt to enumerate it amongſt
thoſe which we call Cœleſtial bodies, was not a poſition ſo foil'd,
and vanquiſh't, as that it had no life left in it; it followeth next,
that we proceed to examine what probability there is for holding
of it fixt, and wholly immoveable, ſcilicet as to its entire Globe,
what likelyhood there is for making it moveable with ſome motion,
and of what kind that may be. And foraſmuch as in this ſame
queſtion I am ambiguous, and Simplicius is reſolute, as likewiſe
Ariſtotle for the opinion of its immobility, he ſhall one by one
produce the arguments in favour of their opinion, and I will
ledge the anſwers and reaſons on the contrary part; and next
gredus ſhall tell us his thoughts, and to which ſide he finds
ſelf inclined.
Too cloſe
ring to Ariſtotle is
blameable.
It is not juſt, that
thoſe who never
philoſophate, ſhould
uſurp the title of
Philoſophers.
The Senſible
World.
SAGR. Content; provided alwayes that I may reſerve the
berty to my ſelf of alledging what pure natural reaſon ſhall
times dictate to me.
SALV. Nay more, it is that which I particularly beg of you;
for, amongſt the more eaſie, and, to ſo ſpeak, material
tions, I believe there are but few of them that have been
ted by Writers, ſo that onely ſome of the more ſubtle, and
mote can be deſired, or wanting; and to inveſtigate theſe, what
other ingenuity can be more ſit than that of the moſt acute and
piercing wit of Sagredus?
1
SAGR. I am what ever pleaſeth Salviatus, but I pray you,
let us not ſally out into another kind of digreſſion complemental;
for at this time I am a Philoſopher, and in the Schools, not in the
Court.
SALV. Let our contemplation begin therefore with this
deration, that whatſoever motion may be aſcribed to the Earth,
it is neceſſary that it be to us, (as inhabitants upon it, and
quently partakers of the ſame) altogether imperceptible, and as if
it were not at all, ſo long as we have regard onely to terreſtrial
things; but yet it is on the contrary, as neceſſary that the ſame

motion do ſeem common to all other bodies, and viſible
jects, that being ſeparated from the Earth, participate not of the
ſame. So that the true method to find whether any kind of motion
may be aſcribed to the Earth, and that found, to know what it
is, is to conſider and obſerve if in bodies ſeparated from the
Earth, one may diſcover any appearance of motion, which

qually ſuiteth to all the reſt; for a motion that is onely ſeen, v. gr.
in the Moon, and that hath nothing to do with Venus or Jupiter,
or any other Stars, cannot any way belong to the Earth, or to
any other ſave the Moon alone. Now there is a moſt general and
grand motion above all others, and it is that by which the Sun,

the Moon, the other Planets, and the Fixed Stars, and in a word,
the whole Univerſe, the Earth onely excepted, appeareth in our
thinking to move from the Eaſt towards the Weſt, in the ſpace of
twenty four hours; and this, as to this firſt appearance, hath no
obſtacle to hinder it, that it may not belong to the Earth alone,
as well as to all the World beſides, the Earth excepted; for the
ſame aſpects will appear in the one poſition, as in the other.
Hence it is that Ariſtotle and Ptolomy, as having hit upon this

ſideration, in going about to prove the Earth to be immoveable,
argue not againſt any other than this Diurnal Motion; ſave onely
that Ariſtotle hinteth ſomething in obſcure terms againſt another
Motion aſcribed to it by an Ancient, of which we ſhall ſpeak in
its place.
The motions of
the Earth are
perceptible to its
inhabitants.
The Earth can
have no other
tions, than thoſe
which to us appear
commune to all the
rest of the
verſe, the Earth
excepted.
The Diurnal
tion, ſeemeth
mune to all the
niverſe, ſave onely
the Earth excepted.
Ariſtotle and
Ptolomy argue
gainſt the
nal Motion
buted to the Earth.
SAGR. I very well perceive the neceſſity of your illation: but
I meet with a doubt which I know not how to free my ſelf from,
and this it is, That Copernicus aſſigning to the Earth another
tion beſide the Diurnal, which, according to the rule even now laid
down, ought to be to us, as to appearance, imperceptible in the
Earth, but viſible in all the reſt of the World; me thinks I may
neceſſarily infer, either that he hath manifeſtly erred in aſſigning
the Earth a motion, to which there appears not a general
ſpondence in Heaven; or elſe that if there be ſuch a congruity
therein, Ptolomy on the other hand hath been deficient in not
futing this, as he hath done the other.
1
SALV. You have good cauſe for your doubt: and when we
come to treat of the other Motion, you ſhall ſee how far
nicus excelled Ptolomey in clearneſs and ſublimity of wit, in that
he ſaw what the other did not, I mean the admirable harmony
wherein that Motion agreed with all the other Cœleſtial Bodies.
But for the preſent we will ſuſpend this particular, and return to
our firſt conſideration; touching which I will proceed to propoſe
(begining with things more general) thoſe reaſons which ſeem to
favour the mobility of the Earth, and then wait the anſwers which

Simplicius ſhall make thereto. And firſt, if we conſider onely
the immenſe magnitude of the Starry Sphere, compared to the
ſmalneſs of the Terreſtrial Globe, contained therein ſo many
lions of times; and moreover weigh the velocity of the motion
which muſt in a day and night make an entire revolution thereof,
I cannot perſwade my ſelf, that there is any man who believes it
more reaſonable and credible, that the Cœleſtial Sphere turneth
round, and the Terreſtrial Globe ſtands ſtill.
Why the diurnal
motion more
bably ſhould belong
to the Earth, than
to the reſt of the
Vniverſe.
SAGR. If from the univerſality of effects, which may in nature
have dependence upon ſuch like motions, there ſhould
ly follow all the ſame conſequences to an hair, aſwell in one
theſis as in the other; yet I for my part, as to my firſt and general
apprehenſion, would eſteem, that he which ſhould hold it more
tional to make the whole Univerſe move, and thereby to ſalve the
Earths mobility, is more unreaſonable than he that being got to
the top of your Turret, ſhould deſire, to the end onely that he
might behold the City, and the Fields about it, that the whole
Country might turn round, that ſo he might not be put to the
trouble to ſtir his head. And yet doubtleſs the advantages would
be many and great which the Copernican Hypotheſis is attended
with, above thoſe of the Ptolomaique, which in my opinion
ſembleth, nay ſurpaſſeth that other folly; ſo that all this makes
me think that far more probable than this. But haply Ariſtotle,
Ptolomey, and Simplicius may find the advantages of their
ſteme, which they would do well to communicate to us alſo, if
any ſuch there be; or elſe declare to me, that there neither are or
can be any ſuch things.
SALV. For my part, as I have not been able, as much as I have
thought upon it, to find any diverſity therein; ſo I think I have
found, that no ſuch diverſity can be in them: in ſo much that I

eſteem it to no purpoſe to ſeek farther after it. Therefore
ſerve: Motion is ſo far Motion, and as Motion operateth, by how
far it hath relation to things which want Motion: but in thoſe
things which all equally partake thereof it hath nothing to do, and
is as if it never were. And thus the Merchandiſes with which a
ſhip is laden, ſo far move, by how far leaving London, they paſs
1by France, Spain, Italy, and ſail to Aleppo, which London, France,
Spain &c. ſtand ſtill, not moving with the ſhip: but as to the
Cheſts, Bales and other Parcels, wherewith the ſhip is ſtow'd and
and laden, and in reſpect of the ſhip it ſelf, the Motion from
don to Syria is as much as nothing; and nothing-altereth the
lation which is between them: and this, becauſe it is common to
all, and is participated by all alike: and of the Cargo which is in
the ſhip, if a Bale were romag'd from a Cheſt but one inch onely,
this alone would be in that Cargo, a greater Motion in reſpect of
the Cheſt, than the whole Voyage of above three thouſand miles,
made by them as they were ſtived together.
Motion, as to the
things that equally
move thereby, is as
of it never were, &
ſo far operates as it
hath relation to
things deprived of
motion.
SIMPL. This Doctrine is good, ſound, and altogether
patetick.
SALV. I hold it to be much more antient: and ſuſpect that A-

riſtotle in receiving it from ſome good School, did not fully
ſtand it, and that therefore, having delivered it with ſome
tion, it hath been an occaſion of confuſion amongſt thoſe, who
would defend whatever he ſaith. And when he writ, that
ſoever moveth, doth move upon ſomething immoveable, I ſuppoſe
that he equivocated, and meant, that whatever moveth, moveth
in reſpect to ſomething immoveable; which propoſition admitteth
no doubt, and the other many.
A propoſition
ken by Ariſtotle
from the Antients,
but ſomewhat
tered by him.
SAGR. Pray you make no digreſſion, but proceed in the
ſertation you began.
SALV. It being therefore manifeſt, that the motion which is

common to many moveables, is idle, and as it were, null as to the
relation of thoſe moveables between themſelves, becauſe that
mong themſelves they have made no change: and that it is
rative onely in the relation that thoſe moveables have to other
things, which want that motion, among which the habitude is
changed: and we having divided the Univerſe into two parts, one
of which is neceſſarily moveable, and the other immoveable; for
the obtaining of whatſoever may depend upon, or be required
from ſuch a motion, it may as well be done by making the Earth
alone, as by making all the reſt of the World to move: for that
the operation of ſuch a motion conſiſts in nothing elſe, ſave in
the relation or habitude which is between the Cœleſtial Bodies,
and the Earth, the which relation is all that is changed. Now if
for the obtaining of the ſame effect ad unguem, it be all one
ther the Earth alone moveth, the reſt of the Univerſe ſtanding
ſtill; or that, the Earth onely ſtanding ſtill, the whole Univerſe

moveth with one and the ſame motion; who would believe, that
Nature (which by common conſent, doth not that by many things,
which may be done by few) hath choſen to make an innumerable
number of moſt vaſt bodies move, and that with an unconceivable
1velocity, to perform that, which might be done by the moderate
motion of one alone about its own Centre?
The firſt diſcourſe
to prove that the
diurnal motion
longs to the Earth.
Nature never
doth that by many
things, which may
be done by a few.
SIMPL. I do not well underſtand, how this grand motion
niſieth nothing as to the Sun, as to the Moon, as to the other
nets, and as to the innumerable multitude of fixed ſtars: or why
you ſhould ſay that it is to no purpoſe for the Sun to paſs from one
Meridian to another; to riſe above this Horizon, to ſet beneath
that other; to make it one while day, another while night: the
like variations are made by the Moon, the other Planets, and the
fixed ſtars themſelves.
SALV. All theſe alterations inſtanced by you, are nothing, ſave
onely in relation to the Earth: and that this is true, do but

magine the Earth to move, and there will be no ſuch thing in the
World as the riſing or ſetting of the Sun or Moon, nor Horizons,
nor Meridians, nor days, nor nights; nor, in a word, will ſuch a
motion cauſe any mutation between the Moon and Sun, or any
other ſtar whatſoever, whether fixed or erratick; but all theſe
changes have relation to the Earth: which all do yet in ſum
import no other than as if the Sun ſhould ſhew it ſelf now to
China, anon to Perſia, then to Egypt, Greece, France, Spain,
merica, &c. and the like holdeth in the Moon, and the reſt of the
Cœleſtial Bodies: which ſelf ſame effect falls out exactly in the
ſame manner, if, without troubling ſo great a part of the Univerſe,

the Terreſtrial Globe be made to revolve in it ſelf. But we will
augment the difficulty by the addition of this other, which is a
very great one, namely, that if you will aſcribe this Great Motion to
Heaven, you muſt of neceſſity make it contrary to the particular
motion of all the Orbs of the Planets, each of which without
controverſie hath its peculiar motion from the Weſt towards the
Eaſt, and this but very eaſie and moderate: and then you make
them to be hurried to the contrary part, i. e. from Eaſt to Weſt,
by this moſt furious diurnal motion: whereas, on the contrary,
making the Earth to move in it ſelf, the contrariety of motions is
taken away, and the onely motion from Weſt to Eaſt is
modated to all appearances, and exactly ſatisfieth every
menon.
The diurnal
tion cauſeth no
mutation amongſt
the Cœleſtial
dies, but all
ges have relation
to the Earth.
A ſccond
firmation that the
diurnal motion
longs to the Earth.
SIMPL. As to the contrariety of Motions it would import

tle, for Ariſtotle demonſtrateth, that circular motions, are not
trary to one another; and that theirs cannot be truly called
trariety.
Circular
ons are not
ry, according to
Ariſtotle.
SALV. Doth Ariſtotle demonſtrate this, or doth he not rather
barely affirm it, as ſerving to ſome certain deſign of his? If
traries be thoſe things, that deſtroy one another, as he himſelf
affirmeth, I do not ſee how two moveables that encounter each
other in a circular line, ſhould leſſe prejudice one another, than if
they interfered in a right line.
1
SAGR. Hold a little, I pray you. Tell me Simplicius, when
two Knights encounter each other, tilting in open field, or when
two whole Squadrons, or two Fleets at Sea, make up to grapple,
and are broken and ſunk, do you call theſe encounters contrary to
one another?
SIMPL. Yes, we ſay they are contrary.
SAGR. How then, is there no contrariety in circular motions.
Theſe motions, being made upon the ſuperſicies of the Earth or
Water, which are, as you know, ſpherical, come to be circular.
Can you tell, Simplicius, which thoſe circular motions be, that
are not contrary to each other? They are (if I miſtake not) thoſe
of two circles, which touching one another without, one thereof
being turn'd round, naturally maketh the other move the
ry ^{*} way; but if one of them ſhall be within the other, it is

poſſible that their motion being made towards different points,
they ſhould not juſtle one another.
As you ſee in a
Mill, wherein the
implicated cogs ſet
the wheels on
ving.
SALV. But be they contrary, or not contrary, theſe are but
alterations of words; and I know, that upon the matter, it would
be far more proper and agreeable with Nature, if we could ſalve
all with one motion onely, than to introduce two that are (if you
will not call them contrary) oppoſite; yet do I not cenſure this
introduction (of contrary motions) as impoſſible; nor pretend I
from the denial thereof, to inferre a neceſſary Demonſtration,
but onely a greater probability, of the other. A third reaſon

which maketh the Ptolomaique Hypotheſis leſſe probable is, that it
moſt unreaſonably confoundeth the order, which we aſſuredly
ſee to be amongſt thoſe Cœleſtial Bodies, the circumgyration of
which is not queſtionable, but moſt certain. And that Order is,

that according as an Orb is greater, it finiſheth its revolution in a
longer time, and the leſſer, in ſhorter. And thus Saturn
bing a greater Circle than all the other Planets, compleateth the
ſame in thirty yeares: Jupiter finiſheth his; that is leſſe, in
twelve years: Mars in two: The Moon runneth thorow hers, ſo
much leſſe than the reſt, in a Moneth onely. Nor do we leſſe
ſenſibly ſee that of the Medicean Stars, which is neareſt to Ju-

piter, to make its revolution in a very ſhort time, that is, in four
and forty hours, or thereabouts, the next to that in three dayes and
an half, the third in ſeven dayes, and the moſt remote in ſixteen.
And this rate holdeth well enough, nor will it at all alter, whileſt
we aſſign the motion of 24 hours to the Terreſtrial Globe, for it
to move round its own center in that time; but if you would have
the Earth immoveable, it is neceſſary, that when you have paſt
from the ſhort period of the Moon, to the others ſucceſſively
bigger, until you come to that of Mars in two years, and from
thence to that of the bigger Sphere of Jupiter in twelve years, and
1from this to the other yet bigger of Saturn, whoſe period is of
thirty years, it is neceſſary, I ſay, that you paſſe to another
Sphere incomparably greater ſtill than that, and make this to

compliſh an entire revolution in twenty four hours. And this yet is
the leaſt diſorder that can follow. For if any one ſhould paſſe
from the Sphere of Saturn to the Starry Orb, and make it ſo
much bigger than that of Saturn, as proportion would require, in
reſpect of its very ſlow motion, of many thouſands of years, then
it muſt needs be a Salt much more abſurd, to skip from this to
another bigger, and to make it convertible in twenty four hours.
But the motion of the Earth being granted, the order of the
riods will be exactly obſerved, and from the very ſlow Sphere of
Saturn, we come to the fixed Stars, which are wholly

ble, and ſo avoid a fourth difficulty, which we muſt of neceſſity
mit, if the Starry Sphere be ſuppoſed moveable, and that is the

immenſe diſparity between the motions of thoſe ſtars themſelves;
of which ſome would come to move moſt ſwiftly in moſt vaſt
cles, others moſt ſlowly in circles very ſmall, according as thoſe
or theſe ſhould be found nearer, or more remote from the Poles;
which ſtill is accompanied with an inconvenience, as well becauſe
we ſee thoſe, of whoſe motion there is no queſtion to be made,
to move all in very immenſe circles; as alſo, becauſe it ſeems to
be an act done with no good conſideration, to conſtitute bodies,
that are deſigned to move circularly, at immenſe diſtances from
the centre, and afterwards to make them move in very ſmall
cles. And not onely the magnitudes of the circles, and
quently the velocity of the motions of theſe Stars, ſhall be moſt

different from the circles and motions of thoſe others, but
(which ſhall be the fifth inconvenience) the ſelf-ſame Stars
ſhall ſucceſſively vary its circles and velocities: For that

thoſe, which two thouſand years ſince were in the Equinoctial,
and conſequently did with their motion deſcribe very vaſt
cles, being in our dayes many degrees diſtant from thence, muſt
of neceſſity become more ſlow of motion, and be reduced to
move in leſſer circles, and it is not altogether impoſſible but that
a time may come, in which ſome of them which in aforetime had
continually moved, ſhall be reduced by uniting with the Pole, to
a ſtate of reſt, and then after ſome time of ceſſation, ſhall return
to their motion again; whereas the other Stars, touching whoſe
motion none ſtand in doubt, do all deſcribe, as hath been ſaid,
the great circle of their Orb, and in that maintain themſelves
without any variation. The abſurdity is farther enlarged (which

let be the ſixth inconvenience) to him that more ſeriouſly
neth the thing, in that no thought can comprehend what ought to
be the ſolidity of that immenſe Sphere, whoſe depth ſo ſtedfaſtly
1holdeth faſt ſuch a multitude of Stars, which without ever
ing fite among themſelves, are with ſo much concord carried
bout, with ſo great diſparity of motions. Or elſe, ſuppoſing the
Heavens to be fluid, as we are with more reaſon to believe, ſo
as that every Star wandereth to and fro in it, by wayes of its
own, what rules ſhall regulate their motions, and to what
poſe, ſo, as that being beheld from the Earth, they appear as if
they were made by one onely Sphere? It is my opinion, that they
might ſo much more eaſily do that, and in a more commodious
manner, by being conſtituted immoveable, than by being made
errant, by how much more facile it is to number the quarries in the
Pavement of a Piazza, than the rout of boyes which run up and
down upon them. And laſtly, which is the ſeventh inſtance, if

we atribute the Diurnal Motion to the higheſt Heaven, it muſt be
conſtituted of ſuch a force and efficacy, as to carry along with
it the innumerable multitude of fixed Stars, Bodies all of vaſt
magnitude, and far bigger than the Earth; and moreover all the
Spheres of the Planets; notwithſtanding that both theſe and thoſe
of their own nature move the contrary way. And beſides all this,
it muſt be granted, that alſo the Element of Fire, and the
er part of the Air, are likewiſe forcibly hurried along with the
reſt, and that the ſole little Globe of the Earth pertinaciouſly
ſtands ſtill, and unmoved againſt ſuch an impulſe; a thing, which
in my thinking, is very difficult; nor can I ſee how the Earth, a
pendent body, and equilibrated upon its centre, expoſed

ferently to either motion or reſt, and environed with a liquid
bient, ſhould not yield alſo as the reſt, and be carried about.
But we find none of theſe obſtacles in making the Earth to move;
a ſmall body, and inſenſible, compared to the Univerſe, and
therefore unable to offer it any violence.
A third
mation of the ſame
Doctrine.
The greater Orbs
make their
ſions in greater
times.
The times of the
Medicean Planets
converſions.
The motion of
24 hours aſcribed
to the higheſt
Sphere diſorders
the period of the
inferiour.
The fourth
firmation.
Great diſparity
amongſt the
ons of the
lar fixed ſtars, if
their Sphere be
moveable.
The fifth
firmation.
The motions of
the fixed ſtars
would accelerate
and grow ſlow in
divers times, if the
ſtarry Sphere were
moueable.
The ſixth
firmatiox.
The Seventh
firmation.
The Earth a
pendent Body, and
equilibrated in a
fluid Medium
ſeems unable to
reſiſt the rapture
of the Diurnal
Motion.
SAGR. I find my fancy diſturbed with certain conjectures ſo
fuſedly ſprung from your later diſcourſes; that, if I would be
bled to apply my ſelf with atention to what followeth, I muſt of
ceſſity attempt whether I can better methodize them, and gather
thence their true conſtruction, if haply any can be made of them;
and peradventure, the proceeding by interrogations may help me
the more eaſily to expreſſe my ſelf. Therefore I demand firſt of
plicius, whether he believeth, that divers motions may
ly agree to one and the ſame moveable body, or elſe that it be
requiſite its natural and proper motion be onely one.
SIMPL. To one ſingle moveable, there can naturally agree

but one ſole motion, and no more; the reſt all happen
tally and by participation; like as to him that walketh upon the
Deck of a Ship, his proper motion is that of his walk, his motion
by participation that which carrieth him to his Port, whither he
1would never with his walking have arrived, if the Ship with its
motion had not wafted him thither.
A ſingle
able hath but onely
one natural
on, and all the
reſt are by
pation.
SAGR. Tell me ſecondly. That motion, which is
cated to any moveable by participation, whileſt it moveth by it
ſelf, with another motion different from the participated, is it
neceſſary, that it do reſide in ſome certain ſubject by it ſelf, or
elſe can it ſubſiſt in nature alone, without other ſupport.
SIMPL. Ariſtotle giveth you an anſwer to all theſe queſtions,

and tels you, that as of one ſole moveable the motion is but one;
ſo of one ſole motion the moveable is but one; and
ly, that without the inherence in its ſubject, no motion can
ther ſubſiſt, or be imagined.
Motion cannot
be made without
its moveable
ject.
SAGR. I would have you tell me in the third place, whether
you beblieve that the Moon and the other Planets and Cœleſtial
bodies, have their proper motions, and what they are.
SIMPL. They have ſo, and they be thoſe according to which
they run through the Zodiack, the Moon in a Moneth, the Sun
in a Year, Mars in two, the Starry Sphere in thoſe ſo many
ſand. And theſe are their proper, or natural motions.
SAGR. But that motion wherewith I ſee the fixed Stars, and
with them all the Planets go unitedly from Eaſt to Weſt, and
turn round to the Eaſt again in twenty four hours, how doth it
agree with them?
SIMPL. It ſuiteth with them by participation.
SAGR. This then reſides not in them, and not reſiding in
them, nor being able to ſubſiſt without ſome ſubject in which it
is reſident, it muſt of force be the proper and natural motion of
ſome other Sphere.
SIMPL. For this purpoſe Aſtronomers, and Philoſophers have
found another high Sphere, above all the reſt, without Stars, to
which Natural agreeth the Diurnal Motion; and this they call
the Primum mobile; the which carrieth along with it all the
feriour Spheres, contributing and imparting its motion to
them.
SAGR. But when, without introducing other Spheres unknown
and hugely vaſt, without other motions or communicated raptures,
with leaving to each Sphere its ſole and ſimple motion, without
intermixing contrary motions, but making all turn one way, as
it is neceſſary that they do, depending all upon one ſole principle,
all things proceed orderly, and correſpond with moſt perfect
mony, why do we reject this Phœnomenon, and give our aſſent to
thoſe prodigious and laborious conditions?
SIMPL. The difficulty lyeth in finding out this ſo natural and
expeditious way.
1
SAGR. In my judgment this is found. Make the Earth the
Primum mobile, that is, make it turn round its own axis in twenty
four hours, and towards the ſame point with all the other Spheres;
and without participating this ſame motion to any other Planet or
Star, all ſhall have their riſings, ſettings, and in a word, all their
other appearances.
SIMPL. The buſineſs is, to be able to make the Earth move
without athouſand inconveniences.
SALV. All the inconveniences ſhall be removed as faſt as you
propound them: and the things ſpoken hitherto are onely the
primary and more general inducements which give us to believe
that the diurnal converſion may not altogether without
lity be applyed to the Earth, rather than to all the reſt of the
niverſe: the which inducements I impoſe not upon you as
lable Axioms, but as hints, which carry with them ſomewhat of
likelihood. And in regard I know very well, that one ſole

periment, or concludent demonſtration, produced on the contrary
part, ſufficeth to batter to the ground theſe and a thouſand other
probable Arguments; therefore it is not fit to ſtay here, but proceed
forwards and hear what Simplicius anſwereth, and what greater
probabilities, or ſtronger arguments he alledgeth on the contrary.
One ſingle
periment, or ſound
demonſtration
tereth down all
guments meerly
probable.
SIMPL. I will firſt ſay ſomething in general upon all theſe
ſiderations together, and then I will deſcend to ſome particulars.
It ſeems that you univerſally bottom all you ſay upon the greater
ſimplicity and facility of producing the ſame effects, whilſt you
hold, that as to the cauſing of them, the motion of the Earth
lone, ſerveth as well as that of all the reſt of the World, the Earth
deducted: but as to the operations, you eſteem that much eaſier
than this. To which I reply, that I am alſo of the ſame opinion,
ſo long as I regard my own not onely finite, but feeble power;
but having a reſpect to the ſtrength of the Mover, which is
finite, its no leſſe eaſie to move the Univerſe, than the Earth,
yea than a ſtraw. And if his power be infinite, why ſhould he not

rather exerciſe a greater part thereof than a leſſe? Therefore,
I hold that your diſcourſe in general is not convincing.
Of an infinite
power one would
think a greater
part ſhould rather
be imploy'd than a
leſſe.
SALV. If I had at any time ſaid, that the Univerſe moved not
for want of power in the Mover, I ſhould have erred, and your
reproof would have been ſeaſonable; and I grant you, that to
an infinite power, it is as eaſie to move an hundred thouſand, as
one. But that which I did ſay, concerns not the Mover, but
ly hath reſpect to the Moveables; and in them, not onely to
their reſiſtance, which doubtleſſe is leſſer in the Earth, than in
the Univerſe; but to the many other particulars, but even now
conſidered. As to what you ſay in the next place, that of an
finite power it is better to exerciſe a great part than a ſmall: I
1ſwer, that of infinite one part is not greater than another, ſince

both are infinite; nor can it be ſaid, that of the infinite number,
an hundred thouſand is a greater part than two, though that be
fifty thouſand times greater than this; and if to the moving of
the Univerſe there be required a finite power, though very great
in compariſon of that which ſufficeth to move the Earth onely;
yet is there not implied therein a greater part of the infinite power,
nor is that part leſſe infinite which remaineth unimploy'd. So that
to apply unto a particular effect, a little more, or a little leſſe
power, importeth nothing; beſides that the operation of ſuch
vertue, hath not for its bound or end the Diurnal Motion onely;
but there are ſeveral other motions in the World, which we
know of, and many others there may be, that are to us unknown.
Therefore if we reſpect the Moveables, and granting it as out of
queſtion, that it is a ſhorter and eaſier way to move the Earth,
than the Univerſe; and moreover, having an eye to the ſo many
other abreviations, and facilities that onely this way are to be
tained, an infallible Maxime of Ariſtotle, which he teacheth us,
that, fruſtra fit per plura, quod poteſt fieri per pauciora,
dereth it more probable that the Diurnal Motion belongs to the
Earth alone, than to the Univerſe, the Earth ſubducted.
Of infinity one
part is no bigger
than auother,
though they are
comparatively
equal.
SIMPL. In reciting that Axiom, you have omitted a ſmall
clauſe, which importeth as much as all the reſt, eſpecially in our
caſe, that is to ſay, the words æquè bene. It is requiſite therefore
to examine whether this Hypotheſis doth equally well ſatisfie in all
particulars, as the other.
SALV. The knowledg whether both theſe poſitions do æquè
bene, ſatisfie, may be comprehended from the particular
nation of the appearances which they are to ſatisfie; for hitherto
we have diſcourſed, and will continue to argue ex hypotheſi,
namely, ſuppoſing, that as to the ſatisfaction of the appearances,

both the aſſumptions are equally accomodated. As to the clauſe
which you ſay was omitted by me, I have more reaſon to ſuſpect
that it was ſuperfluouſly inſerted by you. For the expreſſion æquè
bene, is a relative that neceſſarily requireth two terms at leaſt,
for a thing cannot have relation to its ſelf, nor do we ſay, v. gr.
reſt to be equally good, as reſt. And becauſe, when we ſay, that
is done in vain by many means, which may be done with fewer,
we mean, that that which is to be done, ought to be the ſame
thing, not two different ones; and becauſe the ſame thing
not be ſaid to be done as well as its ſelf; therefore, the addition
of the Phraſe æquè bene is ſuperfluous, and a relation, that hath
but one term onely.
In the Axiome
Fruſtra fit per
ra, &c. the
tion of æque benè,
is ſuperfluous.
SAGR. Unleſſe you will have the ſame befal us, as did
day, let us return to our matter in hand; and let Simplicius
1gin to produce thoſe difficulties that ſeem in his opinion, to thwart
this new diſpoſition of the World.
SIMPL. That diſpoſition is not new, but very old, and that
you may ſee it is ſo, Ariſtotle confuteth it; and his confutations
are theſe: “Firſt if the Earth moveth either in it felf about its

own Centre, or in an Excentrick Circle, it is neceſſary that that
ſame motion be violent; for it is not its natural motion, for
if it were, each of its parts would partake thereof; but each
of them moveth in a right line towards its Centre. It being
therefore violent and pteternatural, it could never be
al: But the order of the World is perpetual. Therefore, &c.
Secondly, all the other moveables that move circularly, ſeem
to ^{*} ſtay behind, and to move with more than one motion, the

Primum Mobile excepted: Whence it would be neceſſary that
the Earth alſo do move with two motions; and if that ſhould
be ſo, it would inevitably follow, that mutations ſhould be
made in the Fixed Stars, the which none do perceive; nay
without any variation, the ſame Stars alwayes riſe from towards
the ſame places, and in the ſame places do ſet. Thirdly, the
tion of the parts is the ſame with that of the whole, and
ly tendeth towards the Centre of the Univerſe; and for the ſame
cauſe reſt, being arrived thither. He thereupon moves the
ſtion whether the motion of the parts hath a tendency to the
centre of the Univerſe, or to the centre of the Earth; and
deth that it goeth by proper inſtinct to the centre of the Univerſe,
and per accidence to that of the Earth; of which point we largely
diſcourſed yeſterday. He laſtly confirmeth the ſame with a fourth
argument taken from the experiment of grave bodies, which
ing from on high, deſcend perpendicularly unto the Earthsſurface;
and in the ſame manner Projections ſhot perpendicularly upwards,
do by the ſame lines return perpendicularly down again, though
they were ſhot to a very great height. All which arguments
ſarily prove their motion to be towards the Centre of the Earth,
which without moving at all waits for, and receiveth them. He
intimateth in the laſt place that the Aſtronomers alledg other
reaſons in confirmation of the ſame concluſions, I mean of the
Earths being in the Centre of the Univerſe, and immoveable;
and inſtanceth onely in one of them, to wit, that all the
nomena or appearances that are ſeen in the motions of the Stars,
perfectly agree with the poſition of the Earth in the Centre;
which would not be ſo, were the Earth ſeated otherwiſe.
The reſt produced by Ptolomy and the other Aſtronomers, I can
give you now if you pleaſe, or after you have ſpoken what you
have to ſay in anſwer to theſe of Ariſtotle.”
Ariſtotles
guments for the
Earths quieſſence.
* Reſtino indietzo,
which is meant
here of that
on which a bowl
makes when its
born by its by as to
one ſide or other,
and ſo hindered in
its direct motion.
SALV. The arguments which are brought upon this occaſion
1are of two kinds: ſome have reſpect to the accidents Terreſtrial,

without any relation to the Stars, and others are taken from the
Phænomena and obſervations of things Cœleſtial. The arguments
of Ariſtotle are for the moſt part taken from things neer at hand,
and he leaveth the others to Aſtronomers; and therefore it is the
beſt way, if you like of it, to examine theſe taken from
ments touching the Earth, and then proceed to thoſe of the other
kind. And becauſe Ptolomy, Tycho, and the other Aſtronomers

and Philoſophers, beſides the arguments of Ariſtotle by them
med, confirmed, and made good, do produce certain others; we
will put them all together, that ſo we may not anſwer twice to
the ſame, or the like objections. Therefore Simplicius, chooſe
whether you will recite them your ſelf, or cauſe me to eaſe you of
this task, for I am ready to ſerve you.
Two kindes of
Arguments
ching the Earths
motion or rest.
Arguments of
Ptolomy and
cho, and other
ſons, over and
bove thoſe of
ſtotle.
SIMPL. It is better that you quote them, becauſe, as having
taken more pains in the ſtudy of them, you can produce them with
more readineſſe, and in greater
The firſt
ment taken from
grave bodies
ling from on high
to the ground.
SALV. All, for the ſtrongeſt reaſon, alledge that of grave
dies, which falling downwards from on high, move by a right line,
that is perpendicular to the ſurface of the Earth, an argument
which is held undeniably to prove that the Earth is immoveable:
for in caſe it ſhould have the diurnal motion, a Tower, from the
top of which a ſtone is let fall, being carried along by the
ſion of the Earth, in the time that the ſtone ſpends in falling, would
be tranſported many hundred yards Eaſtward, and ſo far diſtant
from the Towers foot would the ſtone come to ground. The
which effect they back with another experiment; to wit, by let­

ting a bullet of lead fall from the round top of a Ship, that lieth at
anchor, and obſerving the mark it makes where it lights, which they
find to be neer the ^{*} partners of the Maſt; but if the ſame bullet

be let fall from the ſame place when the ſhip is under ſail, it ſhall
light as far from the former place, as the ſhip hath run in the time
of the leads deſcent; and this for no other reaſon, than becauſe
the natural motion of the ball being at liberty is by a right line

wards the centre of the Earth. They fortiſie this argument with
the experiment of a projection ſhot on high at a very great
ſtance; as for example, a ball ſent out of a Cannon, erected
pendicular to the horizon, the which ſpendeth ſo much time in
cending and falling, that in our parallel the Cannon and we both
ſhould be carried by the Earth many miles towards the Eaſt, ſo
that the ball in its return could never come neer the Peece, but

would fall as far Weſt, as the Earth had run Eaſt. They againe
adde a third, and very evident experiment, ſcilicet, that ſhooting a
bullet point blank (or as Gunners ſay, neither above nor under
tal) out of a Culverin towards the Eaſt, and afterwards another,
1with the ſame charge, and at the ſame elevation or diſport towards
the Weſt, the range towards the Weſt ſhould be very much
ter then the other towards the Eaſt: for that whil'ſt the ball goeth
Weſtward, and the Peece is carried along by the Earth Eaſtward,
the ball will fall from the Peece as far diſtant as is the aggregate of
the two motions, one made by it ſelf towards the Weſt, and the
other by the Peece carried about by the Earth towards the Eaſt;
and on the contrary, from the range of the ball ſhot Eaſtward you
are to ſubſtract the ſpace the Peece moved, being carried after it.
Now ſuppoſe, for example, that the range of the ball ſhot Weſt
were five miles, and that the Earth in the ſame parallel and in the
time of the Bals ranging ſhould remove three miles, the Ball in this
caſe would fall eight miles diſtant from the Culverin, namely, its
own five Weſtward, and the Culverins three miles Eaſtward: but
the range of the ſhot towards the Eaſt would be but two miles
long, for ſo much is the remainder, after you have ſubſtracted
from the five miles of the range, the three miles which the Peece
had moved towards the ſame part. But experience ſheweth the
Ranges to be equal, therefore the Culverin, and conſequently the
Earth are immoveable. And the ſtability of the Earth is no leſfe

confirmed by two other ſhots made North and South; for they
would never hit the mark, but the Ranges would be alwayes wide,
or towards the Weſt, by meanes of the remove the mark would
make, being carried along with the Earth towards the Eaſt, whil'ſt
the ball is flying. And not onely ſhots made by the Meridians,

but alſo thoſe aimed Eaſt or Weſt would prove uncertain; for
thoſe aim'd Eaſt would be too high, and thoſe directed Weſt too
low, although they were ſhot point blank, as I ſaid. For the
Range of the Ball in both the ſhots being made by the Tangent,
that is, by a line parallel to the Horizon, and being that in the
urnal motion, if it be of the Earth, the Horizon goeth continually
deſcending towards the Eaſt, and riſing from the Weſt (therefore
the Oriental Stars ſeem to riſe, and the Occidental to decline) ſo
that the Oriental mark would deſcend below the aime, and
upon the ſhot would fly too high, and the aſcending of the
ern mark would make the ſhot aimed that way range too low; ſo
that the Peece would never carry true towards any point; and for
that experience telleth us the contrary, it is requiſite to ſay, that
the Earth is immoveable.
Which is
med by the
ment of a body let
fall from the round
top of a Ship.
* That is, at the
foot of the Maſt,
upon the upper
deck.
The ſecond
gument taken from
a Projection ſhot
very high.
The third
ment taken from
the ſhots of a
non, towards the
Eaſt, and towards
the West.
This argument
is confirmed by two
ſhots towards the
South and towards
the North.
And it is
wiſe confirmed by
two ſhots towards
the Eaſt, and
wards the Weſt.
SIMPL. Theſe are ſolid reaſons, and ſuch as I believe no man
can anſwer.
SALV. Perhaps they are new to you?
SIMPL. Really they are; and now I ſee with how many
mirable experiments Nature is pleaſed to favour us, wherewith to
aſſiſt us in the knowledge of the Truth. Oh! how exactly one
1truth agreeth with another, and all conſpire to render each other
inexpugnable!
SAGR. What pity it is that Guns were not uſed in Ariſtotles
age, he would with help of them have eaſily battered down
norance, and ſpoke without hæſitation of theſe mundane points.
SALV. I am very glad that theſe reaſons are new unto you, that
ſo you may not reſt in the opinion of the major part of
ticks, who believe, that if any one forſakes the Doctrine of
ſtotle, it is becauſe they did not underſtand or rightly apprehend
his demonſtrations. But you may expect to hear of other

ties, and you ſhall ſee the followers of this new Syſteme produce
gainſt themſelves obſervations, experiences, and reaſons of farre
greater force than thoſe alledged by Aristotle, Ptolomy, and other
oppoſers of the ſame concluſions, and by this means you ſhall come
to aſcertain your ſelf that they were not induced through want of
knowledge or experience to follow that opinion.
Copernicus his
followers are not
moved through
nor ance of the
guments on the
ther part.
SAGR. It is requiſite that upon this occaſion I relate unto you
ſome accidents that befell me, ſo ſoon as I firſt began to hear ſpeak
of this new doctrine. Being very young, and having ſcarcely
niſhed my courſe of Philoſophy, which I left off, as being ſet upon
other employments, there chanced to come into theſe parts a
tain Foreigner of Roſtock, whoſe name, as I remember, was Chri-

ſtianus Vurſtitius, a follower of Copernicus, who in an Academy
made two or three Lectures upon this point, to whom many flock't
as Auditors; but I thinking they went more for the novelty of the
ſubject than otherwiſe, did not go to hear him: for I had
ded with my ſelf that that opinion could be no other than a ſolemn
madneſſe. And queſtioning ſome of thoſe who had been there, I
perceived they all made a jeſt thereof, execpt one, who told me
that the buſineſſe was not altogether to be laugh't at, and becauſe
this man was reputed by me to be very intelligent and wary, I
pented that I was not there, and began from that time forward as
oft as I met with any one of the Copernican perſwaſion, to demand
of them, if they had been alwayes of the ſame judgment; and of as
many as I examined, I found not ſo much as one, who told me not
that he had been a long time of the contrary opinion, but to have
changed it for this, as convinced by the ſtrength of the reaſons
ving the ſame: and afterwards queſtioning them, one by one; to
ſee whether they were well poſſeſt of the reaſons of the other ſide;

I found them all to be very ready and perfect in them; ſo that I
could not truly ſay, that they had took up this opinion out of
norance, vanity, or to ſhew the acuteneſſe of their wits. On the
contrary, of as many of the Peripateticks and Ptolomeans as I
have asked (and out of curioſity I have talked with many) what
pains they had taken in the Book of Copernicus, I found very
1few that had ſo much as ſuperficially peruſed it; but of thoſe
whom, I thought, had underſtood the ſame, not one; and
over, I have enquired amongſt the followers of the Peripatetick
Doctrine, if ever any of them had held the contrary opinion, and
likewiſe found none that had. Whereupon conſidering that there
was no man who followed the opinion of Copernicus, that had
not been firſt on the contrary ſide, and that was not very well
quainted with the reaſons of Ariſtotle and Ptolomy; and, on the
contrary, that there is not one of the followers of Ptolomy that
had ever been of the judgment of Copernicus, and had left that,
to imbrace this of Ariſtotle, conſidering, I ſay, theſe things, I
began to think, that one, who leaveth an opinion imbued with
his milk, and followed by very many, to take up another owned
by very few, and denied by all the Schools, and that really
ſeems a very great Paradox, muſt needs have been moved, not
to ſay forced, by more powerful reaſons. For this cauſe, I am
become very curious to dive, as they ſay, into the bottom of this
buſineſſe, and account it my great good fortune that I have met
you two, from whom I may without any trouble, hear all that
hath been, and, haply, can be ſaid on this argument, aſſuring
my ſelf that the ſtrength of your reaſons will reſolve all ſcruples,
and bring me to a certainty in this ſubject.
Chriſtianus
ſtitius read certain
Lectures touching
the opinion of
pernicus, & what
enſued thereupon.
The followers of
Copernicus were
all firſt againſt
that opinion, but
the Sectators of
Ariſtotle &
lomy, were never
of the other ſide.
SIMPL. But its poſſible your opinion and hopes may be
pointed, and that you may find your ſelves more at a loſſe in the
end than you was at firſt.
SAGR. I am very confident that this can in no wiſe befal
me.
SIMPL. And why not? I have a manifeſt example in my ſelf,
that the farther I go, the more I am confounded.
SAGR. This is a ſign that thoſe reaſons that hitherto ſeemed
concluding unto you, and aſſured you in the truth of your
nion, begin to change countenance in your mind, and to let you
by degrees, if not imbrace, at leaſt look towards the contrary
nent; but I, that have been hitherto indifferent, do greatly hope
to acquire reſt and ſatisfaction by our future diſcourſes, and you
will not deny but I may, if you pleaſe but to hear what
deth me to this expectation.
SIMPL. I will gladly hearken to the ſame, and ſhould be no
leſſe glad that the like effect might be wrought in me.
SAGR. Favour me therefore with anſwering to what I ſhall ask
you. And firſt, tell me, Simplicius, is not the concluſion, which
we ſeek the truth of, Whether we ought to hold with Ariſtotle
and Ptolomy, that the Earth onely abiding without motion in the
Centre of the Univerſe, the Cœleſtial bodies all move, or elſe,
Whether the Starry Sphere and the Sun ſtanding ſtill in the Centre,
1the Earth is without the ſame, and owner of all thoſe motions that
in our ſeeming belong to the Sun and fixed Stars?
SIMPL. Theſe are the concluſions which are in diſpute.
SAGR. And theſe two concluſions, are they not of ſuch a
ture, that one of them muſt neceſſarily be true, and the other
falſe?
SIMPL. They are ſo. We are in a Dilemma, one part of which
muſt of neceſſity be true, and the other untrue; for between
tion and Reſt, which are contradictories, there cannot be inſtanced
a third, ſo as that one cannot ſay the Earth moves not, nor ſtands
ſtill; the Sun and Stars do not move, and yet ſtand not ſtill.
SAGR. The Earth, the Sun, and Stars, what things are they in
nature? are they petite things not worth our notice, or grand and
worthy of conſideration?
SIMPL They are principal, noble, integral bodies of the
verſe, moſt vaſt and conſiderable.
SAGR. And Motion, and Reſt, what accidents are they in

Motion and reſt
principal accidents
in nature.
SIMPL. So great and principal, that Nature her ſelf is defined
by them.
SAGR. So that moving eternally, and the being wholly
veable are two conditions very conſiderable in Nature, and
cate very great diverſity; and eſpecially when aſcribed to the
principal bodies of the Univerſe, from which can enſue none but
very different events.
SIMPL. Yea doubtleſſe.
SAGR. Now anſwer me to another point. Do you believe that
in Logick, Rhethorick, the Phyſicks, Metaphyſicks, Mathematicks,
and finally, in the univerſality of Diſputations there are arguments
ſufficient to perſwade and demonſtrate to a perſon the fallacious,
no leſſe then the true concluſions?
Vntruths cannot
be demonstrated,
as Truths are.
SIMPL. No Sir; rather I am very confident and certain, that
for the proving of a true and neceſſary concluſion, there are in

nature not onely one, but many very powerfull demonſtrations:
and that one may diſcuſſe and handle the ſame divers and ſundry
wayes, without ever falling into any abſurdity; and that the more
any Sophiſt would diſturb and muddy it, the more clear would its
certainty appear: And that on the contrary to make a falſe
tion paſſe for true, and to perſwade the belief thereof, there
not be any thing produced but fallacies, Sophiſms, Paralogiſmes,
Equivocations, and Diſcourſes vain, inconſiſtant, and full of
pugnances and contradictions.
For proof of true
concluſions, many
ſolid arguments
may be produced,
but to prove a
ſity, none.
SAGR. Now if eternal motion, and eternal reſt be ſo
pal accidents of Nature, and ſo different, that there can depend
on them only moſt different conſequences, and eſpecially when
1applyed to the Sun, and to the Earth, ſo vaſt and famous bodies
of the Univerſe; and it being, moreover, impoſſible, that one of
two contradictory Propoſitions, ſhould not be true, and the other
falſe; and that for proof of the falſe one, any thing can be
duced but fallacies; but the true one being perſwadeable by all
kind of concluding and demonſtrative arguments, why ſhould
you think that he, of you two, who ſhall be ſo fortunate as to
maintain the true Propoſition ought not to perſwade me? You
muſt ſuppoſe me to be of a ſtupid wit, perverſe judgment, dull
mind and intellect, and of a blind reaſon, that I ſhould not be
able to diſtinguiſh light from darkneſſe, jewels from coals, or
truth from falſhood.
SIMPL. I tell you now, and have told you upon other
occaſions, that the beſt Maſter to teach us how to diſcern
phiſmes, Paralogiſmes, and other fallacies, was Ariſtotle, who
in this particular can never be deceived.
SAGR. You inſiſt upon Aristotle, who cannot ſpeak. Yet I
tell you, that if Ariſtotle were here, he would either yield

ſelf to be perſwaded by us, or refuting our arguments, convince
us by better of his own. And you your ſelf, when you heard the
experiments of the Suns related, did you not acknowledg and
admire them, and confeſſe them more concludent than thoſe of
Ariſtotle? Yet nevertheleſſe I cannot perceive that Salviatus,
who hath produced them, examined them, and with exquiſite
care ſcan'd them, doth confeſſe himſelf perſwaded by them; no
nor by others of greater force, which he intimated that he was
about to give us an account of. And I know not on what grounds
you ſhould cenſure Nature, as one that for many Ages hath
been lazie, and forgetful to produce ſpeculative wits; and
that knoweth not how to make more ſuch, unleſſe they be ſuch
kind of men as ſlaviſhly giving up their judgments to Ariſtotle, do
underſtand with his brain, and reſent with his ſenſes. But let us
hear the reſidue of thoſe reaſons which favour his opinion, that
we may thereupon proceed to ſpeak to them; comparing and
weighing them in the ballance of impartiality.
Ariſtotle would
either refute his
adverſaries
ments, or would
alter his opinion.
SALV. Before I proceed any farther, I muſt tell Sagredus, that
in theſe our Diſputations, I perſonate the Copernican,, and
tate him, as if I were his Zany; but what hath been effected in
my private thoughts by theſe arguments which I ſeem to alledg in
his favour, I would not have you to judg by what I ſay, whil'ſt
I am in the heat of acting my part in the Fable; but after I have
laid by my diſguiſe, for you may chance to find me different
from what you ſee me upon the Stage. Now let us go on.
Ptolomy and his followers produce another experiment like to

that of the Projections, and it is of things that being ſeparated
1from the Earth, continue a good ſpace of time in the Air, ſuch
as are the Clouds, Birds of flight; and as of them it cannot be
ſaid that they are rapt or tranſparted by the Earth, having no
heſion thereto, it ſeems not poſſible, that they ſhould be able to
keep pace with the velocity thereof; nay it ſhould rather ſeem
to us, that they all ſwiftly move towards the Weſt: And if
being carried about by the Earth, paſſe our parallel in twenty
four hours, which yet is at leaſt ſixteen thouſand miles, how can
Birds follow ſuch a courſe or revolution? Whereas on the
trary, we ſee them fly as well towards the Eaſt, as towards the
Weſt, or any other part, without any ſenſible difference.

over, if when we run a Horſe at his ſpeed, we feel the air beat
vehemently againſt our face, what an impetuous blaſt ought we
perpetually to feel from the Eaſt, being carried with ſo rapid a
courſe againſt the wind? and yet no ſuch effect is perceived. Take
another very ingenious argument inferred from the following

periment. The circular motion hath a faculty to extrude and
ſipate from its Centre the parts of the moving body, whenſoever
either the motion is not very ſlow, or thoſe parts are not very
well faſtened together; and therefore, if v. g. we ſhould turn
one of thoſe great wheels very faſt about, wherein one or more
men walking, crane up very great weights, as the huge maſſie
ſtone, uſed by the Callander for preſſing of Cloaths; or the
fraighted Barks which being haled on ſhore, are hoiſted out of
one river into another; in caſe the parts of that ſame Wheel ſo
ſwiftly turn'd round, be not very well joyn'd and pin'd together,
they would all be ſhattered to pieces; and though many ſtones or
other ponderous ſubſtances, ſhould be very faſt bound to its outward
Rimme, yet could they not reſiſt the impetuoſity, which with
great violence would hurl them every way far from the Wheel,
and conſequently from its Centre. So that if the Earth did move
with ſuch and ſo much greater velocity, what gravity, what
city of lime or plaiſter would keep together Stones, Buildings, and
whole Cities, that they ſhould not be toſt into the Air by ſo
cipitous a motion? And both men and beaſts, which are not
ſtened to the Earth, how could they reſiſt ſo great an impetus?
Whereas, on the other ſide, we ſee both theſe, and far leſſe
ſiſtances of pebles, ſands, leaves reſt quietly on the Earth, and
to return to it in falling, though with a very ſlow motion. See
here, Simplicius, the moſt potent arguments, taken, to ſo ſpeak,
from things Terreſtrial; there remain thoſe of the other kind,
namely, ſuch as have relation to the appearances of Heaven,
which reaſons, to confeſſe the truth, tend more to prove the
Earth to be in the centre of the Univerſe, and conſequently, to
deprive it of the annual motion about the ſame, aſcribed unto it
1by Copernicus. Which arguments, as being of ſomewhat a
rent nature, may be produced, after we have examined the
ſtrength of theſe already propounded.
An argument
taken from the
Clouds, and from
Birds.
An argument
taken from the air
which we feel to
beat upon us when
we run a Horſe at
full ſpeed.
An argument
taken from the
whirling of
lar motion, which
hath a faculty to
extrude and
pate.
SAGR. What ſay you Simplicius? do you think that Salviatus
is Maſter of, and knoweth how to unfold the Ptolomean and
ſtotelian arguments? Or do you think that any Peripatetick is
qually verſt in the Copernican demonſtrations?
SIMPL. Were it not for the high eſteem, that the paſt
ſes have begot in me of the learning of Salviatus, and of the
cuteneſſe of Sagredus, I would by their good leave have gone my
way without ſtaying for their anſwers; it ſeeming to me a thing
impoſſible, that ſo palpable experiments ſhould be contradicted;
and would, without hearing them farther, conſirm my ſelf in my
old perſwaſion; for though I ſhould be made to ſee that it was
roneous, its being upheld by ſo many probable reaſons, would
der it excuſeable. And if theſe are fallacies, what true
tions were ever ſo fair?
SAGR. Yet its good that we hear the reſponſions of Salviatus;
which if they be true, muſt of neceſſity be more fair, and that by
inſinite degrees; and thoſe muſt be deformed, yea moſt deformed,
if the Metaphy ſical Axiome hold, That true and fair are one and

the ſame thing; as alſo falſe and deformed. Therefore Salviatus
let's no longer loſe time.
True and fair
are one and the
ſame, as alſo falſe
and deformed.
SALV. The firſt Argument alledged by Simplicius, if I well
member it, was this. The Earth cannot move circularly, becauſe
ſuch motion would be violent to the ſame, and therefore not
petual: that it is violent, the reaſon was: Becauſe, that had it been
natural, its parts would likewiſe naturally move round, which is
impoſſible, for that it is natural for the parts thereof to move with a
right motion downwards. To this my reply is, that I could
ly wiſh, that Ariſtotle had more cleerly expreſt himſelf, where he

ſaid; That its parts would likewiſe move circularly; for this
ving circularly is to be underſtood two wayes, one is, that every
particle or atome ſeparated from its Whole would move circularly
about its particular centre, deſcribing its ſmall Circulets; the other
is, that the whole Globe moving about its centre in twenty four
hours, the parts alſo would turn about the ſame centre in four and
twenty hours. The firſt would be no leſſe an impertinency, than
if one ſhould ſay, that every part of the circumference of a Circle
ought to be a Circle; or becauſe that the Earth is Spherical, that
therefore every part thereof be a Globe, for ſo doth the Axiome
require: Eadem eſt ratio totius, & partium. But if he took it in
the other ſenſe, to wit, that the parts in imitation of the Whole
ſhould move naturally round the Centre of the whole Globe in
twenty four hours, I ſay, that they do ſo; and it concerns you,
1inſtead of Ariſtotle, to prove that they do not.
The anſwer to
Ariſtotles firſt
gument.
SIMPL. This is proved by Ariſtotle in the ſame place, when he
ſaith, that the natural motion of the parts is the right motion
downwards to the centre of the Univerſe; ſo that the circular
motion cannot naturally agree therewith.
SALV. But do not you ſee, that thoſe very words carry in them
a confutation of this ſolution?
SIMPL. How? and where?
SALV. Doth not he ſay that the circular motion of the Earth
would be violent? and therefore not eternal? and that this is
ſurd, for that the order of the World is eternal?
SIMPL. He ſaith ſo.
SALV. But if that which is violent cannot be eternal, then by

converſion, that which cannot be eternal, cannot be natural: but
the motion of the Earth downwards cannot be otherwiſe eternal;
therefore much leſſe can it be natural: nor can any other motion
be natural to it, ſave onely that which is eternal. But if we make
the Earth move with a circular motion, this may be eternal to it,
and to its parts, and therefore natural.
That which is
violent, cannot be
eternal, and that
which cannot be
ternal, cannot be
natural.
SIMPL. The right motion is moſt natural to the parts of the
Earth, and is to them eternal; nor ſhall it ever happen that they
move not with a right motion; alwayes provided that the
diments be removed.
SALV. You equivocate Simplicius; and I will try to free you
from the equivoke. Tell me, therefore, do you think that a
Ship which ſhould ſail from the Strait of Gibralter towards
ſtina can eternally move towards that Coaſt? keeping alwayes an
equal courſe?
SIMPL. No doubtleſſe.
SALV. And why not?
SIMPL. Becauſe that Voyage is bounded and terminated
tween the Herculean Pillars, and the ſhore of the Holy-land; and
the diſtance being limited, it is paſt in a finite time, unleſſe one by
returning back ſhould with a contrary motion begin the ſame
age anew; but this would be an interrupted and no continued
motion.
SALV. Very true. But the Navigation from the Strait of
galanes by the Pacifick Ocean, the Moluccha's, the Cape di buona
Speranza, and from thence by the ſame Strait, and then again by
the Pacifick Ocean, &c. do you believe that it may be
tuated?
SIMPL. It may; for this being a circumgyration, which
turneth about its ſelf, with infinite replications, it may be
ated without any interruption.
SALV. A Ship then may in this Voyage continue ſailing
nally.
1
SIMPL. It may, in caſe the Ship were incorruptible, but the
Ship decaying, the Navigation muſt of neceſſity come to an end.
SALV. But in the Mediterrane, though the Veſſel were
ruptible, yet could ſhe not ſail perpetually towards Paleſtina, that

Voyage being determined. Two things then are required, to the
end a moveable may without intermiſſion move perpetually; the
one is, that the motion may of its own nature be indeterminate and
infinite; the other, that the moveable be likewiſe incorruptible
and eternal.
Two things
quiſite to the end a
motion may
petuate it ſelf; an
unlimited ſpace,
and an
ble moveable.
SIMPL. All this is neceſſary.
SALV. Therefore you may ſee how of your own accord you
have confeſſed it impoſſible that any moveable ſhould move
nally in a right line, in regard that right motion, whether it be

wards, or downwards, is by you your ſelf bounded by the
ference and centre; ſo that if a Moveable, as ſuppoſe the Earth
be eternal, yet foraſmuch as the right motion is not of its own
ture eternall, but moſt ^{*}terminate, it cannot naturally ſuit with

the Earth. Nay, as was ſaid ^{*} yeſterday, Ariſtotle himſelf is

conſtrained to make the Terreſtrial Globe eternally immoveable.
When again you ſay, that the parts of the Earth evermore move
downwards, all impediments being removed, you egregiouſly
vocate; for then, on the other ſide they muſt be impeded,
ried, and forced, if you would have them move; for, when they
are once fallen to the ground, they muſt be violently thrown
wards, that they may a ſecond time fall; and as to the
ments, theſe only hinder its arrival at the centre; but if there were
a Well, that did paſſe thorow and beyond the centre, yet would not
a clod of Earth paſſe beyond it, unleſſe inaſmuch as being
ported by its impetus, it ſhould paſſe the ſame to return thither
gain, and in the end there to reſt. As therefore to the defending,
that the motion by a right line doth or can agree naturally neither
to the Earth, nor to any other moveable, whil'ſt the Univerſe
taineth its perfect order, I would have you take no further paines
bout it, but (unleſſe you will grant them the circular motion)
your beſt way will be to defend and maintain their immobility.
Right motion
cannot be eternal,
and conſequently
cannot be natural
to the Earth.
* Terminatiſſimo.
* By this
on he every where
means the
ding Dialogue, or
Giornata.
SIMPL. As to their immoveableneſſe, the arguments of
ſtotle, and moreover thoſe alledged by your ſelf ſeem in my
on neceſſarily to conclude the ſame, as yet; and I conceive it will
be a hard matter to refute them.
SALV. Come we therefore to the ſecond Argument, which was,
That thoſe bodies, which we are aſſured do move circularly, have

more than one motion, unleſſe it be the Primum Mobile; and
therefore, if the Earth did move circularly, it ought to have two
motions; from which alterations would follow in the riſing and
ſetting of the Fixed Stars: Which effect is not perceived to enſue.
1Therefore, &c. The moſt proper and genuine anſwer to this
gation is contained in the Argument it ſelf; and even Aristotle
puts it in our mouths, which it is impoſſible, Simplicius, that you
ſhould not have ſeen.
The anſwer to
the ſecond
ment.
SIMPL. I neither have ſeen it, nor do I yet apprehend it.
SALV. This cannot be, ſure, the thing is ſo very plain.
SIMPL. I will with your leave, caſt an eye upon the Text.
SAGR. We will command the Text to be brought forthwith.
SIMPL. I alwayes carry it about with me: See here it is, and
I know the place perfectly well, which is in lib. 2. De Cælo, cap.
16. Here it is, Text 97. Preterea omnia, quæ feruntur latione
circulari ſubdeficere videntur, ac moveri pluribus una latione,
præter primam Sphæram; quare & Terram neceſſariam eſt, ſive
circa medium, ſive in medio poſita feratur, duabus moveri
lationibus. Si autem hoc acciderit, neceſſariam eſt fieri
tiones, ac converſiones fixorum aſtrorum. Hoc autem non
tur ficri, ſed ſemper eadem, apud eadem loca ipſius, &
tur, & occidunt. [In Engliſh thus:] Furthermore all that are

carried with circular motion, ſeem to ^{*} foreſlow, and to move
with more than one motion, except the firſt Sphere; wherefore
it is neceſſary that the Earth move with two motions, whether

it be carried about the ^{*} middle, or placed in the middle. But
if it be ſo, there would of neceſſity be alterations and
ons made amongſt the fixed Stars. But no ſuch thing is ſeen to
be done, but the ſame Star doth alwayes riſe and ſet in the ſame
place. In all this I find not any falacy, and my thinks the
ment is very forcible.
* Subdeſicere.
* Or Centre.
SALV. And this new reading of the place hath confirmed me
in the fallacy of the Sillogiſme, and moreover, diſcovered
ther falſity. Therefore obſerve. The Poſitions, or if you will,
Concluſions, which Ariſtotle endeavours to oppoſe, are two; one
is that of thoſe, who placing the Earth in the midſt of the World,
do make it move in it ſelf about its own centre. The other is of
thoſe, who conſtituting it far from the middle, do make it
volve with a circular motion about the middle of the Univerſe.
And both theſe Poſitions he conjointly impugneth with one and
the ſame argument. Now I affirm that he is out in both the one
and the other impugnation; and that his error againſt the firſt
Poſition is an Equivoke or Paralogiſme; and his miſtake

ing the ſecond is a falſe conſequence. Let us begin with the firſt
Aſſertion, which conſtituteth the Earth in the midſt of the
World, and maketh it move in it ſelf about its own centre; and

let us confront it with the objection of Ariſtotle; ſaying, All
moveables, that move circularly, ſeem to ^{*} foreſlow, and move
with more than one Byas, except the firſt Sphere (that is the pri-
1mum mobile) therefore the Earth moving about its own centre,
being placed in the middle, muſt of neceſſity have two byaſſes,
and foreſlow. But if this were ſo, it would follow, that there
ſhould be a variation in the riſing and ſetting of the fixed Stars,
which we do not perceive to be done: Therefore the Earth doth
not move, &c. Here is the Paralogiſme, and to diſcover it, I will
argue with Ariſtotle in this manner. Thou ſaiſt, oh Ariſtotle,
that the Earth placed in the middle of the World, cannot move
in it ſelf (i. e. upon its own axis) for then it would be requiſite
to allow it two byaſſes; ſo that, if it ſhould not be neceſſary to
allow it more than one Byas onely, thou wouldeſt not then hold
it impoſſible for it to move onely with that one; for thou would'ſt
unneceſſarily have conſined the impoſſibility to the plurality of
byaſſes, if in caſe it had no more but one, yet it could not move
with that. And becauſe that of all the moveables in the World,
thou makeſt but one alone to move with one ſole byas; and all
the reſt with more than one; and this ſame moveable thou
firmeſt to be the firſt Sphere, namely, that by which all the
ed and erratick Stars ſeem harmoniouſly to move from Eaſt to
Weſt, if in caſe the Earth may be that firſt Sphere, that by
ving with one by as onely, may make the Stars appear to move
from Eaſt to Weſt, thou wilt not deny them it: But he that
firmeth, that the Earth being placed in the midſt of the World,
moveth about its own Axis, aſcribes unto it no other motion,
ſave that by which all the Stars appear to move from Eaſt to Weſt;
and ſo it cometh to be that firſt Sphere, which thou thy ſelf
knowledgeſt to move with but one by as onely. It is therefore
ceſſary, oh Ariſtotle, if thou wilt conclude any thing, that thou
demonſtrate, that the Earth being placed in the midſt of the
World, cannot move with ſo much as one by as onely; or elſe,
that much leſſe can the firſt Sphere have one ſole motion; for
therwiſe thou doeſt in thy very Sillogiſme both commit the falacy,
and detect it, denying, and at that very time proving the ſame
thing. I come now to the ſecond Poſition, namely, of thoſe
who placing the Earth far from the midſt of the Univerſe, make
it moveable about the ſame; that is, make it a Planet and
tick Star; againſt which the argument is directed, and as to
form is concludent, but faileth in matter. For it being granted,
that the Earth doth in that manner move, and that with two
aſſes, yet doth it not neceſſarily follow that though it were ſo,
it ſhould make alterations in the riſings and ſettings of the fixed
Stars, as I ſhall in its proper place declare. And here I could
gladly excuſe Ariſtotle; rather I could highly applaud him for
ving light upon the moſt ſubtil argument that could be produced
againſt the Copernican Hypotheſis; and if the objection be
1nious, and to outward appearance moſt powerful, you may ſee
how much more acute and ingenious the ſolution muſt be, and
not to be found by a wit leſſe piercing than that of Copernicus;
and again from the difficulty in underſtanding it, you may argue
the ſo much greater difficulty in finding it. But let us for the
ſent ſuſpend our anſwer, which you ſhall underſtand in due time
and place, after we have repeated the objection of Ariſtotle, and
that in his favour, much ſtrengthened. Now paſſe we to Ari-

ſtotles third Argument, touching which we need give no farther
reply, it having been ſufficiently anſwered betwixt the diſcourſes
of yeſterday and to day: In as much as he urgeth, that the
tion of grave bodies is naturally by a right line to the centre; and
then enquireth, whether to the centre of the Earth, or to that
of the Univerſe, and concludeth that they tend naturally to the
centre of the Univerſe, but accidentally to that of the Earth.

Therefore we may proceed to the fourth, upon which its requiſite
that we ſtay ſome time, by reaſon it is founded upon that
riment, from whence the greater part of the remaining
ments derive all their ſtrength. Ariſtotle ſaith therefore, that it is
a moſt convincing argument of the Earths immobility, to ſee
that projections thrown or ſhot upright, return perpendicularly
by the ſame line unto the ſame place from whence they were ſhot
or thrown. And this holdeth true, although the motion be of a
very great height; which could never come to paſſe, did the
Earth move: for in the time that the projected body is moving
upwards and downwards in a ſtate of ſeparation from the Earth,
the place from whence the motion of the projection began, would
be paſt, by means of the Earths revolution, a great way
wards the Eaſt, and look how great that ſpace was, ſo far from
that place would the projected body in its deſcent come to the
ground. So that hither may be referred the argument taken from
a bullet ſhot from a Canon directly upwards; as alſo that other
uſed by Ariſtotle and Ptolomy, of the grave bodies that falling
from on high, are obſerved to deſcend by a direct and
lar line to the ſurface of the Earth. Now that I may begin to untie
theſe knots, I demand of Simplicius that in caſe one ſhould deny
to Ptolomy and Ariſtotle that weights in falling freely from on
high, deſcend by a right and perpendicular line, that is, directly
to the centre, what means he would uſe to prove it?
Ariſtotles
ment againſt the
Earths motion, is
defective in two
things
* The ſame word
which a little above
I tendred ſtay
hind, as a bowle
when it meets with
ruls.
The anſwer to
the third
ment.
The anſwer to
the fourth
ment.
SIMPL. The means of the ſenſes; the which aſſureth us, that
that Tower or other altitude, is upright and perpendicular, and
ſheweth us that that ſtone, or other grave body, doth ſlide along
the Wall, without inclining a hairs breadth to one ſide or
ther, and light at the foot thereof juſt under the place from whence
it was let fall.
1
SALV. But if it ſhould happen that the Terreſtrial Globe did
move round, and conſequently carry the Tower alſo along with
it, and that the ſtone did then alſo grate and ſlide along the ſide of
the Tower, what muſt its motion be then?
SIMPL. In this caſe we may rather ſay its motions: for it
would have one wherewith to deſcend from the top of the Tower
to the bottom, and ſhould neceſſarily have another to follow the
courſe of the ſaid Tower.
SALV. So that its motion ſhould be compounded of two, to
wit, of that wherewith it meaſureth the Tower, and of that
ther wherewith it followeth the ſame: From which compoſition
would follow, that the ſtone would no longer deſcribe that ſimple
right and perpendicular line, but one tranſverſe, and perhaps not
ſtreight.
SIMPL. I can ſay nothing of its non-rectitude, but this I know
very well, that it would of neceſſity be tranſverſe, and different
from the other directly perpendicular, which it doth deſcribe, the
Earth ſtanding ſtill.
SALV. You ſee then, that upon the meer obſerving the falling
ſtone to glide along the Tower, you cannot certainly affirm that
it deſcribeth a line which is ſtreight and perpendicular, unleſs you
firſt ſuppoſe that the Earth ſtandeth ſtill.
SIMPL. True; for if the Earth ſhould move, the ſtones
tion would be tranſverſe, and not perpendicular.
SALV. Behold then the Paralogiſm of Ariſtotle and Ptolomey

to be evident and manifeſt, and diſcovered by you your ſelf,
wherein that is ſuppoſed for known, which is intended to be
monſtrated.
The Paralogiſm
of Ariſtotle and
Ptolomey in
poſing that for
known, which is in
queſtion.
SIMPL. How can that be? To me it appeareth that the
Syllogiſm is rightly demonſtrated without petitionem principii.
SALV. You ſhall ſee how it is; anſwer me a little. Doth he
not lay down the concluſion as unknown?
SIMPL. Unknown; why otherwiſe the demonſtrating it would
be ſuperfluous.
SALV. But the middle term, ought not that to be known?
SIMPL. Its neceſſary that it ſhould; for otherwiſe it would be
a proving ignotum per æquè ignotum.
SALV. Our concluſion which is to be proved, and which is
known, is it not the ſtability of the Earth?
SIMPL. It is the ſame.
SALV. The middle term, which ought to be known, is it not the
ſtreight and perpendicular deſcent of the ſtone?
SIMPL. It is ſo.
SALV. But was it not juſt now concluded, that we can have
no certain knowledg whether that ſame ſhall be direct and
1dicular, unleſs we firſt know that the Earth ſtands ſtill? Therefore
in your Syllogiſm the certainty of the middle term is aſſumed
from the uncertainty of the concluſion. You may ſee then, what
and how great the Paralogiſm is.
SAGR. I would, in favour of Simplicius, defend Ariſtotle if it
were poſſible, or at leaſt better ſatisfie my ſelf concerning the
ſtrength of your illation. You ſay, that the ſeeing the ſtone rake
along the Tower, is not ſufficient to aſſure us, that its motion is
perpendicular (which is the middle term of the Syllogiſm) unleſs
it be preſuppoſed, that the Earth ſtandeth ſtill, which is the
cluſion to be proved: For that if the Tower did move together
with the Earth, and the ſtone did ſlide along the ſame, the motion
of the ſtone would be tranſverſe, and not perpendicular. But I
ſhall anſwer, that ſhould the Tower move, it would be impoſſible
that the ſtone ſhould fall gliding along the ſide of it; and
fore from its falling in that manner the ſtability of the Earth is
ferred.
SIMPL. It is ſo; for if you would have the ſtone in
ing to grate upon the Tower, though it were carried round by
the Earth, you muſt allow the ſtone two natural motions, to wit,
the ſtraight motion towards the Centre, and the circular about
the Centre, the which is impoſſible.
SALV. Ariſtotles defenſe then conſiſteth in the impoſſibilitie,
or at leaſt in his eſteeming it an impoſſibility, that the ſtone ſhould
move with a motion mixt of right and circular: for if he did
not hold it impoſſible that the ſtone could move to the Centre,
and about the Centre at once, he muſt have underſtood, that it
might come to paſs that the cadent ſtone might in its deſcent, race
the Tower as well when it moved as when it ſtood ſtill; and
ſequently he muſt have perceived, that from this grating nothing
could be inferred touching the mobility or immobility of the
Earth. But this doth not any way excuſe Aristotle; aſwell
cauſe he ought to have expreſt it, if he had had ſuch a conceit, it
being ſo material a part of his Argument; as alſo becauſe it can
neither be ſaid that ſuch an effect is impoſſible, nor that Ariſtotle
did eſteem it ſo. The firſt cannot be affirmed, for that by and
by I ſhall ſhew that it is not onely poſſible, but neceſſary: nor

much leſs can the ſecond be averred, for that Ariſtotle himſelf
granteth fire to move naturally upwards in a right line, and to
move about with the diurnal motion, imparted by Heaven to the
whole Element of Fire, and the greater part of the Air: If
fore he held it not impoſſible to mix the right motion upwards,
with the circular communicated to the Fire and Air from the
cave of the Moon, much leſs ought he to account impoſſible the
mixture of the right motion downwards of the ſtone, with the
1circular which we preſuppoſe natural to the whole Terreſtrial
Globe, of which the ſtone is a part.
Ariſtotle
teth that the Fire
moveth directly
upwards by
ture, and round
bout by
tion.
SIMPL. I ſee no ſuch thing: for if the element of Fire
volve round together with the Air, it is a very eaſie, yea a neceſſary
thing, that a ſpark of fire which from the Earth mounts upwards,
in paſſing thorow the moving air, ſhould receive the ſame motion,
being a body ſo thin, light, and eaſie to be moved: but that a
very heavy ſtone, or a Canon bullet, that deſcendeth from on
high, and that is at liberty to move whither it will, ſhould ſuffer
it ſelf to be tranſported either by the air or any other thing, is
altogether incredible. Beſides that, we have the Experiment,
which is ſo proper to our purpoſe, of the ſtone let fall from the
round top of the Maſt of a ſhip, which when the ſhip lyeth ſtill,
falleth at the Partners of the Maſt; but when the ſhip ſaileth, falls
ſo far diſtant from that place, by how far the ſhip in the time of
the ſtones falling had run forward; which will not be a few
thoms, when the ſhips courſe is ſwift.
SALV. There is a great diſparity between the caſe of the Ship

and that of the Earth, if the Terreſtrial Globe be ſuppoſed to have
a diurnal motion. For it is a thing very manifeſt, that the
tion of the Ship, as it is not natural to it, ſo the motion of all thoſe
things that are in it is accidental, whence it is no wonder that the
ſtone which was retained in the round top, being left at liberty,
deſcendeth downwards without any obligation to follow the
tion of the Ship. But the diurnal converſion is aſcribed to the
Terreſtrial Globe for its proper and natural motion, and
quently, it is ſo to all the parts of the ſaid Globe; and, as being
impreſs'd by nature, is indelible in them; and therefore that ſtone
that is on the top of the Tower hath an intrinſick inclination of
revolving about the Centre of its Whole in twenty four hours, and
this ſame natural inſtinct it exerciſeth eternally, be it placed in any
ſtate whatſoever. And to be aſſured of the truth of this, you
have no more to do but to alter an antiquated impreſſion made
in your mind; and to ſay, Like as in that I hitherto holding it to
be the property of the Terreſtrial Globe to reſt immoveable about
its Centre, did never doubt or queſtion but that all whatſoever
particles thereof do alſo naturally remain in the ſame ſtate of reſt:
So it is reaſon, in caſe the Terreſtrial Globe did move round by
natural inſtinct in twenty four hours, that the intrinſick and
ral inclination of all its parts ſhould alſo be, not to ſtand ſtill, but

to follow the ſame revolution. And thus without running into
any inconvenience, one may conclude, that in regard the motion
conferred by the force of ^{*}Oars on the Ship, and by it on all the
things that are contained within her, is not natural but forreign, it
is very reaſonable that that ſtone, it being ſeparated from the ſhip,
1do reduce its ſelf to its natural diſpoſure, and return to exerciſe

its pure ſimple inſtinct given it by nature. To this I add, that
it's neceſſary, that at leaſt that part of the Air which is beneath the
greater heights of mountains, ſhould be tranſported and carried
round by the roughneſs of the Earths ſurface; or that, as being
mixt with many Vapours, and terrene Exhalations, it do
turally follow the diurnal motion, which occurreth not in the
Air about the ſhip rowed by Oars: So that your arguing
from the ſhip to the Tower hath not the force of an illation;
becauſe that ſtone which falls from the round top of the Maſt,
entereth into a medium, which is unconcern'd in the motion
of the ſhip: but that which departeth from the top of the Tower,
finds a medium that hath a motion in common with the whole
reſtrial Globe; ſo that without being hindred, rather being aſſiſted
by the motion of the air, it may follow the univerſal courſe of the
Earth.
The diſparity
tween the fall of a
ſtone from the
round top of a ſhip,
and from the top
of a tower.
*That you may not
ſuſpect my
tion, or wonder
what Oars have to
do with a ſhip, you
are to know that
the Author intends
the Gallies uſed in
the Mediterrane.
The part of the
Air inferiour to
the higher
tains doth follow
the motion of the
Earth.
SIMPL. I cannot conceive that the air can imprint in a very

great ſtone, or in a groſs Globe of Wood or Ball of Lead, as
ſuppoſe of two hundred weight, the motion wherewith its ſelf is
moved, and which it doth perhaps communicate to feathers, ſnow,
and other very light things: nay, I ſee that a weight of that
ture, being expoſed to any the moſt impetuous wind, is not
by removed an inch from its place; now conſider with your ſelf
whether the air will carry it along therewith.
The motion of the
Air apt to carry
with it light things
but not heavy.
SALV. There is great difference between your experiment and
our caſe. You introduce the wind blowing againſt that ſtone,
ſuppoſed in a ſtate of reſt, and we expoſe to the air, which already
moveth, the ſtone which doth alſo move with the ſame velocity;
ſo that the air is not to conferr a new motion upon it, but onely
to maintain, or to ſpeak better, not to hinder the motion already
acquired: you would drive the ſtone with a ſtrange and
natural motion, and we deſire to conſerve it in its natural. If
you would produce a more pertinent experiment, you ſhould ſay,
that it is obſerved, if not with the eye of the forehead, yet with
that of the mind, what would evene, if an eagle that is carried by
the courſe of the wind, ſhould let a ſtone fall from its talons;
which, in regard that at its being let go, it went along with the
wind, and after it was let fall it entered into a medium that
ved with equal velocity, I am very confident that it would not be
ſeen to deſcend in its fall perpendicularly, but that following the
courſe of the wind, and adding thereto that of its particular
vity, it would move with a tranſverſe motion.
SIMPI. But it would firſt be known how ſuch an experiment
may be made; and then one might judg according to the event.
In the mean time the effect of the ſhip doth hitherto incline to
vour our opinion.
1
SALV. Well ſaid you hitherto, for perhaps it may anon change
countenance. And that I may no longer hold you in ſuſpenſe,
tell me, Simplicius, do you really believe, that the Experiment of
the ſhip ſquares ſo very well with our purpoſe, as that it ought to
be believed, that that which we ſee happen in it, ought alſo to
evene in the Terreſtrial Globe?
SIMPL. As yet I am of that opinion; and though you have
alledged ſome ſmall diſparities, I do not think them of ſo great
moment, as that they ſhould make me change my judgment.
SALV. I rather deſire that you would continue therein, and
hold for certain, that the effect of the Earth would exactly anſwer
that of the ſhip: provided, that when it ſhall appear prejudicial to
your cauſe, you would not be humorous and alter your thoughts.
You may haply ſay, Foraſmuch as when the ſhip ſtands ſtill, the
ſtone falls at the foot of the Maſt, and when ſhe is under ſail, it
lights far from thence, that therefore by converſion, from the ſtones
falling at the foot is argued the ſhips ſtanding ſtill, and from its
falling far from thence is argued her moving; and becauſe that
which occurreth to the ſhip, ought likewiſe to befall the Earth:
that therefore from the falling of the ſtone at the foot of the
er is neceſſarily inferred the immobility of the Terreſtrial Globe.
Is not this your argumentation?
SIMPL. It is; and reduced into that conciſeneſs, as that it is
become moſt eaſie to be apprehended.
SALV. Now tell me; if the ſtone let fall from the
top, when the ſhip is in a ſwift courſe, ſhould fall exactly in
the ſame place of the ſhip, in which it falleth when the ſhip is at
anchor, what ſervice would theſe experiments do you, in order to
the aſcertaining whether the veſſel doth ſtand ſtill or move?
SIMPL. Juſt none: Like as, for exemple, from the beating of
the pulſe one cannot know whether a perſon be aſleep or awake,
ſeeing that the pulſe beateth after the ſame manner in ſleeping as
in waking.
SALV. Very well. Have you ever tryed the experiment of the
Ship?
SIMPL. I have not; but yet I believe that thoſe Authors
which alledg the ſame, have accurately obſerved it; beſides that
the cauſe of the diſparity is ſo manifeſtly known, that it admits
of no queſtion.
SALV. That it is poſſible that thoſe Authors inſtance in it,
without having made tryal of it, you your ſelf are a good
mony, that without having examined it, alledg it as certain, and in
a credulous way remit it to their authority; as it is now not onely
poſſible, but very probable that they likewiſe did; I mean, did
remit the ſame to their Predeceſſors, without ever arriving at one
1that had made the experiment: for whoever ſhall examine the
ſame, ſhall find the event ſucceed quite contrary to what hath
been written of it: that is, he ſhall ſee the ſtone fall at all times
in the ſame place of the Ship, whether it ſtand ſtill, or move with
any whatſoever velocity. So that the ſame holding true in the

Earth, as in the Ship, one cannot from the ſtones falling
dicularly at the foot of the Tower, conclude any thing touching
the motion or reſt of the Earth.
The stone falling
from the Mast of
a ſhip lights in the
ſame place,
ther the ſhip doth
move or ly still.
SIMPL. If you ſhould refer me to any other means than to
experience, I verily believe our Diſputations would not come to
an end in haſte; for this ſeemeth to me a thing ſo remote from all
humane reaſon, as that it leaveth not the leaſt place for credulity
or probability.
SALV. And yet it hath left place in me for both.
SIMPL. How is this? You have not made an hundred, no nor
one proof thereof, and do you ſo confidently affirm it for true?
I for my part will return to my incredulity, and to the confidence
I had that the Experiment hath been tried by the principal
thors who made uſe thereof, and that the event ſucceeded as they
affirm.
SALV. I am aſſured that the effect will enſue as I tell you; for ſo
it is neceſſary that it ſhould: and I farther add, that you know your
ſelf that it cannot fall out otherwiſe, however you feign or ſeem to
feign that you know it not. Yet I am ſo good at taming of wits,
that I will make you confeſs the ſame whether you will or no. But
Sagredus ſtands very mute, and yet, if I miſtake not, I ſaw him
make an offer to ſpeak ſomewhat.
SAGR. I had an intent to ſay ſomething, but to tell you true, I
know not what it was; for the curioſity that you have moved in me,
by promiſing that you would force Simplicius to diſcover the
knowledg which he would conceal from us, hath made me to
poſe all other thoughts: therefore I pray you to make good your
vaunt.
SALV. Provided that Simplicius do conſent to reply to what I
ſhall ask him, I will not fail to do it.
SIMPL. I will anſwer what I know, aſſured that I ſhall not be
much put to it, for that of thoſe things which I hold to be falſe,
I think nothing can be known, in regard that Science reſpecteth
truths and not falſhoods.
SALV. I deſire not that you ſhould ſay or reply, that you know
any thing, ſave that which you moſt aſſuredly know. Therefore
tell me; If you had here a flat ſuperficies as polite as a
glaſs, and of a ſubſtance as hard as ſteel, and that it were not
ralel to the Horizon, but ſomewhat inclining, and that upon it
you did put a Ball perfectly ſpherical, and of a ſubſtance grave and
1hard, as ſuppoſe of braſs; what think you it would do being let
go? do not you believe (as for my part I do) that it would lie
ſtill?
SIMPL. If that ſuperficies were inclining?
SALV. Yes; for ſo I have already ſuppoſed.
SIMPL. I cannot conceive how it ſhould lie ſtill: nay, I am
confident that it would move towards the declivity with much
penſneſs.
SALV. Take good heed what you ſay, Simplicius, for I am
confident that it would lie ſtill in what ever place you ſhould lay
it.
SIMPL. So long as you make uſe of ſuch ſuppoſitions,
viatus, I ſhall ceaſe to wonder if you inferr moſt abſurd
cluſions.
SALV. Are you aſſured, then, that it would freely move
wards the declivity?
SIMPL. Who doubts it?
SALV. And this you verily believe, not becauſe I told you ſo,
(for I endeavoured to perſwade you to think the contrary) but of
your ſelf, and upon your natural judgment.
SIMPL. Now I ſee what you would be at; you ſpoke not this
as really believing the ſame; but to try me, and to wreſt matter
out of my own mouth wherewith to condemn me.
SALV. You are in the right. And how long would that Ball
move, and with what velocity? But take notice that I inſtanced
in a Ball exactly round, and a plain exquiſitely poliſhed, that all
external and accidental impediments might be taken away. And
ſo would I have you remove all obſtructions cauſed by the Airs
ſiſtance to diviſion, and all other caſual obſtacles, if any other
there can be.
SIMPL. I very well underſtand your meaning, and as to your
demand, I anſwer, that the Ball would continue to move in
finitum, if the inclination of the plain ſhould ſo long laſt, and
tinually with an accelerating motion; for ſuch is the nature of
ponderous moveables, that vires acquirant eundo: and the
er the declivity was, the greater the velocity would be.
SALV. But if one ſhould require that that Ball ſhould move
upwards on that ſame ſuperficies, do you believe that it would
ſo do?
SIMPL. Not ſpontaneouſly; but being drawn, or violently
thrown, it may.
SALV. And in caſe it were thruſt forward by the impreſſion of
ſome violent impetus from without, what and how great would
its motion be?
SIMPL. The motion would go continually decreaſing and
1tarding, as being contrary to nature; and would be longer or
ſhorter, according to the greater or leſs impulſe, and according to
the greater or leſs acclivity.
SALV. It ſeems, then, that hitherto you have explained to me
the accidents of a moveable upon two different Planes; and that
in the inclining plane, the grave moveable doth ſpontaneouſly
ſcend, and goeth continually accelerating, and that to retain it in
reſt, force muſt be uſed therein: but that on the aſcending plane,
there is required a force to thruſt it forward, and alſo to ſtay it in
reſt, and that the motion impreſſed goeth continually diminiſhing,
till that in the end it cometh to nothing. You ſay yet farther,
that in both the one and the other caſe, there do ariſe differences
from the planes having a greater or leſs declivity or acclivity; ſo
that the greater inclination is attended with the greater velocity;
and contrariwiſe, upon the aſcending plane, the ſame moveable
thrown with the ſame force, moveth a greater diſtance, by how
much the elevation is leſs. Now tell me, what would befall the
ſame moveable upon a ſuperficies that had neither acclivity nor
declivity?
SIMPL. Here you muſt give me a little time to conſider of an
anſwer. There being no declivity, there can be no natural
nation to motion: and there being no acclivity, there can be no
reſiſtance to being moved; ſo that there would ariſe an
rence between propenſion and reſiſtance of motion; therefore,
methinks it ought naturally to ſtand ſtill. But I had forgot my
ſelf: it was but even now that Sagredus gave me to underſtand
that it would ſo do.
SALV. So I think, provided one did lay it down gently: but
if it had an impetus given it towards any part, what would
low?
SIMP. There would follow, that it ſhould move towards that
part.
SALV. But with what kind of motion? with the continually
accelerated, as in declining planes; or with the ſucceſſively
tarded, as in thoſe aſcending.
SIMP. I cannot tell how to diſcover any cauſe of acceleration,
or retardation, there being no declivity or acclivity.
SALV. Well: but if there be no cauſe of retardation, much
leſs ought there to be any cauſe of reſt. How long therefore
would you have the moveable to move?
SIMP. As long as that ſuperficies, neither inclined nor
ned ſhall laſt.
SALV. Therefore if ſuch a ſpace were interminate, the motion
upon the ſame would likewiſe have no termination, that is, would
be perpetual.
1
SIMP. I think ſo, if ſo be the moveable be of a matter
durable.
SALV. That hath been already ſuppoſed, when it was ſaid,
that all external and accidental impediments were removed, and
the brittleneſſe of the moveable in this our caſe, is one of thoſe
impediments accidental. Tell me now, what do you think is the
cauſe that that ſame Ball moveth ſpontaneouſly upon the inclining
plane, and not without violence upon the erected?
SIMP. Becauſe the inclination of grave bodies is to move
wards the centre of the Earth, and onely by violence upwards
wards the circumference; and the inclining ſuperficies is that
which acquireth vicinity to the centre, and the aſcending one,
remoteneſſe.
SALV. Therefore a ſuperficies, which ſhould be neither
clining nor aſcending, ought in all its parts to be equally
ſtant from the centre. But is there any ſuch ſuperficies in the
World?
SIMP. There is no want thereof: Such is our Terreſtrial
Globe, if it were more even, and not as it is rough and
nous; but you have that of the Water, at ſuch time as it is calm
and ſtill.
SALV. Then a ſhip which moveth in a calm at Sea, is one of
thoſe moveables, which run along one of thoſe ſuperficies that
are neither declining nor aſcending, and therefore diſpoſed, in
caſe all obſtacles external and accidental were removed, to move
with the impulſe once imparted inceſſantly and uniformly.
SIMPL. It ſhould ſeem to be ſo.
SALV. And that ſtone which is on the round top, doth not it
move, as being together with the ſhip carried about by the
cumference of a Circle about the Centre; and therefore
quently by a motion in it indelible, if all extern obſtacles be
removed? And is not this motion as ſwift as that of the ſhip.
SIMPL. Hitherto all is well. But what followeth?
SALV. Then in good time recant, I pray you, that your laſt
concluſion, if you are ſatisfied with the truth of all the
miſes.
SIMPL. By my laſt concluſion, you mean, That that ſame
ſtone moving with a motion indelibly impreſſed upon it, is not to
leave, nay rather is to follow the ſhip, and in the end to light in
the ſelf ſame place, where it falleth when the ſhip lyeth ſtill; and
ſo I alſo grant it would do, in caſe there were no outward
diments that might diſturb the ſtones motion, after its being let
go, the which impediments are two, the one is the moveables
inability to break through the air with its meer impetus onely, it
being deprived of that of the ſtrength of Oars, of which it had
1been partaker, as part of the ſhip, at the time that it was upon
the Maſt; the other is the new motion of deſcent, which alſo
muſt needs be an hinderance of that other progreſſive motion.
SALV. As to the impediment of the Air, I do not deny it
you; and if the thing falling were a light matter, as a feather,
or a lock of wool, the retardation would be very great, but in
an heavy ſtone is very exceeding ſmall. And you your ſelf but
even now did ſay, that the force of the moſt impetuous wind
ſufficeth not to ſtir a great ſtone from its place; now do but
ſider what the calmer air is able to do, being encountred by a
ſtone no more ſwift than the whole ſhip. Nevertheleſſe, as I ſaid
before, I do allow you this ſmall effect, that may depend upon
ſuch an impediment; like as I know, that you will grant to me,
that if the air ſhould move with the ſame velocity that the ſhip
and ſtone hath, then the impediment would be nothing at all.
As to the other of the additional motion downwards; in the firſt
place it is manifeſt, that theſe two, I mean the circular, about
the centre, and the ſtreight, towards the centre, are not
ries, or deſtructive to one another, or incompatible. Becauſe that
as to the moveable, it hath no repugnance at all to ſuch motions,
for you your ſelf have already confeſt the repugnance to be
gainſt the motion which removeth from the centre, and the
nation to be towards the motion which approacheth to the centre.
Whence it doth of neceſſity follow, that the moveable hath
ther repugnance, nor propenſion to the motion which neither
proacheth, nor goeth from the centre, nor conſequently is there
any cauſe for the diminiſhing in it the faculty impreſſed. And
aſmuch as the moving cauſe is not one alone, which it hath
tained by the new operation of retardation; but that they are
two, diſtinct from each other, of which, the gravity attends
ly to the drawing of the moveable towards the centre, and the
vertue impreſs't to the conducting it about the centre, there
maineth no occaſion of impediment.
SIMPL. Your argumentation, to give you your due, is very
probable; but in reality it is invelloped with certain intricacies,
that are not eaſie to be extricated. You have all along built upon

a ſuppoſition, which the Peripatetick Schools will not eaſily grant
you, as being directly contrary to Aristotle, and it is to take for
known and manifeſt, That the project ſeparated from the
cient, continueth the motion by vertue impreſſed on it by the
ſaid projicient, which vertue impreſſed is a thing as much
ſted in Peripatetick Philoſophy, as the paſſage of any accident
from one ſubject into another. Which doctrine doth hold, as I
believe it is well known unto you, that the project is carried by
the medium, which in our caſe happeneth to be the Air. And
1therefore if that ſtone let fall from the round top, ought to
low the motion of the ſhip, that effect ſhould be aſcribed to the
Air, and not to the vertue impreſſed. But you preſuppoſe that
the Air doth not follow the motion of the ſhip, but is tranquil.
Moreover, he that letteth it fall, is not to throw it, or to give
it impetus with his arm, but ought barely to open his hand and let
it go; and by this means, the ſtone, neither through the vertue
impreſſed by the projicient, nor through the help of the Air,
ſhall be able to follow the ſhips motion, and therefore ſhall be
left behind.
The project
cording to
tle, is not moved by
vertue impreſſed,
but by the medium.
SALV. I think then that you would ſay, that if the ſtone be
not thrown by the arm of that perſon, it is no longer a
jection.
SIMPL. It cannot be properly called a motion of projection.
SALV. So then that which Ariſtotle ſpeaks of the motion, the
moveable, and the mover of the projects, hath nothing to do
with the buſineſſe in hand; and if it concern not our purpoſe,
why do you alledg the ſame?
SIMP. I produce it on the oceaſion of that impreſſed vertue,
named and introduced by you, which having no being in the
World, can be of no force; for non-entium nullæ ſunt
nes; and therefore not onely of projected, but of all other
ternatural motions, the moving cauſe ought to be aſcribed to the
medium, of which there hath been no due conſideration had;
and therefore all that hath been ſaid hitherto is to no purpoſe.
SALV. Go to now, in good time. But tell me, ſeeing that
your inſtance is wholly grounded upon the nullity of the vertue
impreſſed, if I ſhall demonſtrate to you, that the medium hath
nothing to do in the continuation of projects, after they are
patated from the projicient, will you admit of the impreſſed
tue, or will you make another attempt to overthrow it?
SIMP. The operation of the medium being removed, I ſee not
how one can have recourſe to any thing elſe ſave the faculty
preſſed by the mover.
SALV. It would be well, for the removing, as much as is
poſſible, the occaſions of multiplying contentions, that you
would explain with as much diſtinctneſſe as may be, what is that
operation of the medium in continuing the motion of the
Operation of the
medium in
ing the motion of
the project.
SIMP. The projicient hath the ſtone in his hand, and with
force and violence throws his arm, with which jactation the
ſtone doth not move ſo much as the circumambient Air; ſo that
when the ſtone at its being forſaken by the hand, findeth it ſelf
in the Air, which at the ſame time moveth with impetouſity, it
is thereby born away; for, if the air did not operate, the ſtone
would fall at the foot of the projicient or thrower.
1
Many
ments, and
ſons againſt the
cauſe of the
on of projects,
ſigned by Ariſtotle.
SALV. And was you ſo credulous, as to ſuffer your ſelf to be
perſwaded to believe theſe fopperies, ſo long as you had your
ſenſes about you to confute them, and to underſtand the
truth thereof? Therefore tell me, that great ſtone, and that
Canon bullet, which but onely laid upon a table, did continue
immoveable againſt the moſt impetuous winds, according as you a
little before did affirm, if it had been a ball of cork or other light
ſtuffe, think you that the wind would have removed it from its
place?
SIMP. Yes, and I am aſſured that it would have blown it
quite away, and with ſo much more velocity, by how much the
matter was lighter, for upon this reaſon we ſee the clouds to be
tranſported with a velocity equal to that of the wind that drives
them.
SALV. And what is the Wind?
SIMP. The Wind is defined to be nothing elſe but air moved.
SALV. Then the moved air doth carry light things more
ſwiftly, and to a greater diſtance, then it doth heavy.
SIMP. Yes certainly.
SALV. But if you were to throw with your arm a ſtone, and a
lock of cotton wool, which would move ſwiſteſt and fartheſt?
SIMP. The ſtone by much; nay the wool would fall at my
feet.
SALV. But, if that which moveth the projected ſubſtance,
ter it is delivered from the hand, be no other than the air moved
by the arm, and the moved air do more eaſily bear away light
than grave matters, how cometh it that the project of wool flieth
not farther, and ſwifter than that of ſtone? Certainly it
eth that the ſtone hath ſome other impulſe beſides the motion of
the air. Furthermore, if two ſtrings of equal length did hang
at yonder beam, and at the end of one there was faſtened a
let of lead, and a ball of cotton wool at the other, and both
were carried to an equal diſtance from the perpendicular, and
then let go; it is not to be doubted, but that both the one and
the other would move towards the perpendicular, and that being
carried by their own impetus, they would go a certain ſpace
yond it, and afterwards return thither again. But which of theſe
two pendent Globes do you think, would continue longeſt in
tion, before that it would come to reſt in its perpendicularity?
SIMP. The ball of lead would ſwing to and again many times,
and that of wool but two or three at the moſt.
SALV. So that that impetus and that mobility whatſoever is
the cauſe thereof, would conſerve its ſelf longer in grave
ſtances, than light; I proceed now to another particular, and
mand of you, why the air doth not carry away that Lemon
which is upon that ſame Table?
1
SIMP. Becauſe that the air it ſelf is not moved
SALV. It is requiſite then, that the projicient do confer
tion on the Air, with which it afterward moveth the project. But
if ſuch a motion cannot be impreſſed [i. e. imparted] it being im­
poſſible to make an accident paſſe out of one ſubject into another,
how can it paſſe from the arm into the Air? Will you ſay that the
Air is not a ſubject different from the arm?
SIMP. To this it is anſwered that the Air, in regard it is
ther heavy nor light in its own Region, is diſpoſed with facility to
receive every impulſe, and alſo to retain the ſame.
SALV. But if thoſe penduli even now named, did prove
unto us, that the moveable, the leſſe it had of gravity, the leſſe
apt it was to conſerve its motion, how can it be that the Air
which in the Air hath no gravity at all, doth of it ſelf alone
tain the motion acquired? I believe, and know that you by this
time are of the ſame opinion, that the arm doth not ſooner
turn to reſt, than doth the circumambient Air. Let's go into the
Chamber, and with a towel let us agitate the Air as much as we
can, and then holding the cloth ſtill, let a little candle be
brought, that was lighted in the next room, or in the ſame place
let a leaf of beaten Gold be left at liberty to flie any wav, and you
ſhall by the calm vagation of them be aſſured that the Air is
diately reduced to tranquilty. I could alledg many other
ments to the ſame purpoſe, but if one of theſe ſhould not
fice, I ſhould think your folly altogether incurable.
SAGR. When an arrow is ſhot againſt the Wind, how
ble a thing is it, that that ſame ſmall filament of air, impelled by
the bow-ſtring, ſhould in deſpite of fate go along with the arrow?
But I would willingly know another particular of Ariſtotle, to
which I intreat Simplicius would vouchſafe me an anſwer.
poſing that with the ſame Bow there were ſhot two arrows, one
juſt after the uſual manner, and the other ſide-wayes, placing it
long-wayes upon the Bow-ſtring, and then letting it flie, I would
know which of them would go fartheſt. Favour me, I pray you
with an anſwer, though the queſtion may ſeem to you rather
ridiculous than otherwiſe; and excuſe me, for that I, who am, as
you ſee, rather blockiſh, than not, can reach no higher with my
ſpeculative faculty.
SIMPL. I have never ſeen an arrow ſhot in that manner, yet
nevertheleſſe I believe, that it would not flie ſide-long, the
twentieth part of the ſpace that it goeth end-wayes.
SAGR. And for that I am of the ſame opinion, hence it is, that
I have a doubt riſen in me, whether Aristotle doth not contradict
experience. For as to experience, if I lay two arrows upon this
Table, in a time when a ſtrong Wind bloweth, one towards
1the courſe of the wind, and the other ſidelong, the wind will
quickly carry away this later, and leave the other where it was;
and the ſame to my ſeeming, ought to happen, if the Doctrine of
Ariſtotle were true, of thoſe two ſhot out of a Bow: foraſmuch
as the arrow ſhot ſideways is driven by a great quantity of Air,
moved by the bowſtring, to wit by as much as the ſaid ſtring is
long, whereas the other arrow receiveth no greater a quantity of
air, than the ſmall circle of the ſtrings thickneſs. And I cannot
imagine what may be the reaſon of ſuch a difference, but would
fain know the ſame.
SIMP. The cauſe ſeemeth to me ſufficiently manifeſt; and it
is, becauſe the arrow ſhot endways, hath but a little quantity of
air to penetrate, and the other is to make its way through a
tity as great as its whole length.
SALV. Then it ſeems the arrows ſhot, are to penetrate the air?
but if the air goeth along with them, yea, is that which carrieth
them, what penetration can they make therein? Do you not ſee
that, in this caſe, the arrow would of neceſſity move with greater
velocity than the air? and this greater velocity, what doth confer
it on the arrow? Will you ſay the air giveth them a velocity
greater than its own? Know then, Simplicius, that the buſineſs
proceeds quite contrary to that which Ariſtotle ſaith, and that the

medium conferreth the motion on the project, is as falſe, as it is
true, that it is the onely thing which procureth its obſtruction; and
having known this, you ſhall underſtand without finding any thing
whereof to make queſtion, that if the air be really moved, it doth
much better carry the dart along with it longways, than endways,
for that the air which impelleth it in that poſture, is much, and in
this very little. But ſhooting with the Bow, foraſmuch as the air
ſtands ſtill, the tranſverſe arrow, being to force its paſſage through
much air, comes to be much impeded, and the other that was nock't
eaſily overcometh the obſtruction of the ſmall quantity of air,
which oppoſeth it ſelf thereto.
The medium doth
impede and not
fer the motion of
projects.
SALV. How many Propoſitions have I obſerved in Ariſtotle,
(meaning ſtill in Natural Philoſophy) that are not onely falſe,
but falſe in ſuch ſort, that its diametrical contrary is true, as it
happens in this caſe. But purſuing the point in hand, I think that
Simplicius is perſwaded, that, from ſeeing the ſtone always to fall
in the ſame place, he cannot conjecture either the motion or
bility of the Ship: and if what hath been hitherto ſpoken,
ſhould not ſuffice, there is the Experiment of the medium which
may thorowly aſſure us thereof; in which experiment, the moſt
that could be ſeen would be, that the cadent moveable might be
left behind, if it were light, and that the air did not follow the
motion of the ſhip: but in caſe the air ſhould move with equal
1velocity, no imaginable diverſity could be found either in this,
or any other experiment whatſoever, as I am anon to tell you.
Now if in this caſe there appeareth no difference at all, what can
be pretended to be ſeen in the ſtone falling from the top of the
Tower, where the motion in gyration is not adventitious, and
cidental, but natural and eternal; and where the air exactly
loweth the motion of the Tower, and the Tower that of the
reſtrial Globe? have you any thing elſe to ſay, Simplicius, upon
this particular?
SIMP. No more but this, that I ſee not the mobility of the
Earth as yet proved.
SALV. Nor have I any intention at this time, but onely to
ſhew, that nothing can be concluded from the experiments
ed by our adverſaries for convincing Arguments: as I think I
ſhall prove the others to be.
SAGR. I beſeech you, Salviatus, before you proceed any
ther, to permit me to ſtart certain queſtions, which have been
rouling in my fancy all the while that you with ſo much patience
and equanimity, was minutely explaining to Simplicius the
riment of the Ship.
SALV. We are here met with a purpoſe to diſpute, and it's fit
that every one ſhould move the difficulties that he meets withall,
for this is the way to come to the knowledg of the truth.
Therefore ſpeak freely.
SAGR. If it be true, that the impetus wherewith the ſhip moves,
doth remain indelibly impreſſ'd in the ſtone, after it is let fall from
the Maſt; and if it be farther true, that this motion brings no
pediment or retardment to the motion directly downwards,
tural to the ſtone: it's neceſſary, that there do an effect enſue of

a very wonderful nature. Let a Ship be ſuppoſed to ſtand ſtill,
and let the time of the falling of a ſtone from the Maſts Round-top
to the ground, be two beats of the pulſe; let the Ship afterwards
be under ſail, and let the ſame ſtone depart from the ſame place,
and it, according to what hath been premiſed, ſhall ſtill take up
the time of two pulſes in its fall, in which time the ſhip will have
run, ſuppoſe, twenty yards; To that the true motion of the ſtone
will be a tranſverſe line, conſiderably longer than the firſt ſtraight
and perpendicular line, which is the length of the ^{*} Maſt, and yet

nevertheleſs the ^{*} ſtone will have paſt it in the ſame time. Let
it be farther ſuppoſed, that the Ships motion is much more
rated, ſo that the ſtone in falling ſhall be to paſs a tranſverſe line
much longer than the other; and in ſum, increaſing the Ships

locity as much as you will, the falling ſtone ſhall deſcribe its
verſe lines ſtill longer and longer, and yet ſhall paſs them all in
thoſe ſelf ſame two pulſes. And in this faſhion, if a Canon were
1level'd on the top of a Tower, and ſhots were made therewith
point blank, that is, paralel to the Horizon, let the Piece have a
greater or leſs charge, ſo as that the ball may fall ſometimes a
thouſand yards diſtant, ſometimes four thouſand, ſometimes ſix,
ſometimes ten, &c. and all theſe ſhots ſhall curry or finiſh their
ranges in times equal to each other, and every one equal to the
time which the ball would take to paſs from the mouth of the
Piece to the ground, being left, without other impulſe, to fall
ſimply downwards in a perpendicular line. Now it ſeems a very
admirable thing, that in the ſame ſhort time of its falling
dicularly down to the ground, from the height of, ſuppoſe, an
hundred yards, the ſame ball, being thruſt violently out of the
Piece by the Fire, ſhould be able to paſs one while four hundred,
another while a thouſand, another while four, another while ten
thouſand yards, ſo as that the ſaid ball in all ſhots made point
blank, always continueth an equal time in the air.
An admirable
accident in the
tion of projects.
*By the length of
the maſt he means
the diſtance
tween the
deck and
top.
* La palla.
SALV. The conſideration for its novelty is very pretty, and if
the effect be true, very admirable: and of the truth thereof, I
make no queſtion: and were it not for the accidental impediment
of the air, I verily believe, that, if at the time of the balls going
out of the Piece, another were let fall from the ſame height
rectly downwards, they would both come to the ground at the
ſame inſtant, though that ſhould have curried ten thouſand
miles in its range, and this but an hundred onely: preſuppoſing
the ſurface of the Earth to be equal, which to be aſſured of, the
experiment may be made upon ſome lake. As for the impediment
which might come from the air, it would conſiſt in retarding the
extreme ſwift motion of the ſhot. Now, if you think fit, we will
proceed to the ſolution of the other Objections, ſeeing that
plicius (as far as I can ſee) is convinc'd of the nullity of this firſt,
taken from things falling from on high downwards.
SIMP. I find not all my ſcruples removed, but it may be the
fault is my own, as not being of ſo eaſie and quick an apprehenſion
as Sagredus. And it ſeems to me, that if this motion, of which
the ſtone did partake whilſt it was on the Round-top of the Ships
Maſt, be, as you ſay, to conſerve it ſelf indelibly in the ſaid ſtone,
even after it is ſeparated from the Ship, it would follow, that
wiſe in caſe any one, riding a horſe that was upon his ſpeed, ſhould
let a bowl drop out of his hand, that bowl being fallen to the
ground would continue its motion and follow the horſes ſteps,
without tarrying behind him: the which effect, I believe, is not
to be ſeen, unleſs when he that is upon the horſe ſhould throw it
with violence that way towards which he runneth; but otherwiſe,
I believe it will ſtay on the ground in the ſame place where it
fell.
1
SALV. I believe that you very much deceive your ſelf, and am
certain, that experience will ſhew you the contrary, and that the ball
being once arrived at the ground, will run together with the horſe,
not ſtaying behind him, unleſs ſo far as the aſperity and
neſs of the Earth ſhall hinder it. And the reaſon ſeems to me
very manifeſt: for if you, ſtanding ſtill, throw the ſaid ball
long the ground, do you think it would not continue its motion
even after you had delivered it out of your hand? and that for ſo
much a greater ſpace, by how much the ſuperficies were more
ſmooth, ſo that v. g. upon ice it would run a great way?
SIMP. There is no doubt of it, if I give it impetus with my
arm; but in the other caſe it is ſuppoſed, that he who is upon the
horſe, onely drops it out of his hand:
SALV. So I deſire that it ſhould be: but when you throw it
with your arm, what other remaineth to the ball being once gone
out of your hand, than the motion received from your arm, which
motion being conſerved in the boul, it doth continue to carry it
forward? Now, what doth it import, that that impetus be
ferred on the ball rather from the arm than from the horſe? Whilſt
you were on horſeback, did not your hand, and conſequently the
ball run as faſt as the horſe it ſelf? Doubtleſs it did: therefore
in onely opening of the hand, the ball departs with the motion
ready conceived, not from your arm, by your particular motion,
but from the motion dependant on the ſaid horſe, which cometh to
be communicated to you, to your arm, to your hand, and laſtly to
the ball. Nay, I will tell you farther, that if the rider upon his
ſpeed fling the ball with his arm to the part contrary to the courſe,
it ſhall, after it is fallen to the ground, ſometimes (albeit thrown to
the contrary part) follow the courſe of the horſe, and ſometimes lie
ſtill on the ground; and ſhall onely move contrary to the ſaid
courſe, when the motion received from the arm, ſhall exceed that
of the carrier in velocity. And it is a vanity, that of ſome, who
ſay that a horſeman is able to caſt a javelin thorow the air, that
way which the horſe runs, and with the horſe to follow and
take the ſame; and laſtly, to catch it again. It is, I ſay, a vanity,
for that to make the project return into the hand, it is requiſite to
caſt it upwards, in the ſame manner as if you ſtood ſtill. For, let
the carrier be never ſo ſwift, provided it be uniform, and the
ject not over-light, it ſhall always fall back again into the hand of
the projicient, though never ſo high thrown.
SAGR. By this Doctrine I come to know ſome Problems very

curious upon this ſubject of projections; the firſt of which muſt
ſeem very ſtrange to Simplicius. And the Problem is this; I
firm it to be poſſible, that the ball being barely dropt or let fall,
by one that any way runneth very ſwiftly, being arrived at the
1Earth, doth not onely follow the courſe of that perſon, but doth
much out go him. Which Problem is connexed with this, that
the moveable being thrown by the projicient above the plane of
the Horizon, may acquire new velocity, greater by far than that
confer'd upon it by the projicient. The which effect I have with
admiration obſerved, in looking upon thoſe who uſe the ſport of
tops, which, ſo ſoon as they are ſet out of the hand, are ſeen to
move in the air with a certain velocity, the which they afterwards
much encreaſe at their coming to the ground; and if whipping
them, they rub at any uneven place that makes them skip on high,
they are ſeen to move very ſlowly through the air, and falling
gain to the Earth, they ſtill come to move with a greater velocity:
But that which is yet more ſtrange, I have farther obſerved, that
they not onely turn always more ſwiftly on the ground, than in
the air, but of two ſpaces both upon the Earth, ſometimes a
tion in the ſecond ſpace is more ſwift than in the firſt. Now what
would Simplicius ſay to this?
Sundry curious
Problems,
ing the motions of
projects.
SIMP. He would ſay in the firſt place, that he had never made
ſuch an obſervation. Secondly, he would ſay, that he did not
lieve the ſame. He would ſay again, in the third place, that if
you could aſſure him thereof, and demonſtratively convince him of
the ſame, he would account you a great Dæmon.
SAGR. I hope then that it is one of the Socratick, not infernal
ones. But that I may make you underſtand this particular, you
muſt know, that if a perſon apprehend not a truth of himſelf, it
is impoſſible that others ſhould make him underſtand it: I may
deed inſtruct you in thoſe things which are neither true nor falſe;
but the true, that is, the neceſſary, namely, ſuch as it is impoſſible
ſhould be otherwiſe, every common capacity either comprehendeth
them of himſelf, or elſe it is impoſſible he ſhould ever know them.
And of this opinion I am confident is Salviatus alſo: and
fore I tell you, that the reaſons of the preſent Problems are known
by you, but it may be, not apprehended.
SIMP. Let us, for the preſent, paſs by that controverſie, and
permit me to plead ignorance of theſe things you ſpeak of, and try
whether you can make me capable of underſtanding theſe
blems.
SAGR. This firſt dependeth upon another, which is, Whence
cometh it, that ſetting a top with the laſh, it runneth farther, and
conſequently with greater force, than when its ſet with the
gers?
SIMP. Ariſtotle alſo makes certain Problems about theſe kinds
of projects.
SALV. He doth ſo; and very ingenious they are:
ly, That, Whence it cometh to paſs that round tops run better than
the ſquare?
1
SAGR. And cannot you, Simplicius, give a reaſon for this,
without others prompting you?
SIMP. Very good, I can ſo; but leave your jeering.
SAGR. In like manner you do know the reaſon of this other
alſo. Tell me therefore; know you that a thing which moveth,
being impeded ſtands ſtill?
SIMP. I know it doth, if the impediment be ſo great as to
ſuffice.
SAGR. Do you know, that moving upon the Earth is a greater
impediment to the moveable, than moving in the air, the Earth
ing rough and hard, and the air ſoft and yielding?
SIMP. And knowing this, I know that the top will turn faſter
in the air, than on the ground, ſo that my knowledg is quite
trary to what you think it.
SAGR. Fair and ſoftly, Simplicius. You know that in the
parts of a moveable, that turneth about its centre, there are found
motions towards all ſides; ſo that ſome aſcend, others deſcend;
ſome go forwards, others backwards?
SIMP. I know it, and Aristotle taught me the ſame.
SAGR. And with what demonſtration, I pray you?
SIMP. With that of ſenſe.
SAGR. Ariſtotle, then, hath made you ſee that which without
him you would not have ſeen? Did he ever lend you his eyes?
You would ſay, that Ariſtotle hath told, advertiſed, remembered
you of the ſame; and not taught you it. When then a top,
out changing place, turns round, (or in the childrens phraſe,
eth) not paralel, but erect to the Horizon, ſome of its parts aſcend,
and the oppoſite deſcend; the ſuperiour go one way, the
riour another. Fancie now to your ſelf, a top, that without
ging place, ſwiftly turns round in that manner, and ſtands
ded in the air, and that in that manner turning, it be let fall to the
Earth perpendicularly, do you believe, that when it is arrived at
the ground, it will continue to turn round in the ſame manner,
without changing place, as before?
SIMP. No, Sir.
SAGR. What will it do then?
SIMP. It will run along the ground very faſt.
SAGR. And towards what part?
SIMP. Towards that, whither its ^{*}reeling carrieth
* Vertigine.
SAGR. In its reeling there are parts, that is the uppermoſt, which
do move contrary to the inferiour; therefore you muſt inſtance
which it ſhall obey: for as to the parts aſcending and deſcending,
the one kind will not yield to the other; nor will they all go
downwards, being hindered by the Earth, nor upwards as being
heavy.
1
SIMP. The top will run reeling along the floor towards that
part whither its upper parts encline it.
SAGR. And why not whither the contrary parts tend, namely,
thoſe which touch the ground?
SIMP. Becauſe thoſe upon the ground happen to be impeded
by the roughneſs of the touch, that is, by the floors unevenneſs;
but the ſuperiour, which are in the tenuous and flexible air, are
hindred very little, if at all; and therefore the top will obey their
inclination.
SAGR. So that that taction, if I may ſo ſay, of the neither
parts on the floor, is the cauſe that they ſtay, and onely the upper
parts ſpring the top forward.
SALV. And therefore, if the top ſhould fall upon the ice, or
other very ſmooth ſuperficies, it would not ſo well run forward, but
might peradventure continue to revolve in it ſelf, (or ſleep)
out acquiring any progreſſive motion.
SAGR. It is an eaſie thing for it ſo to do; but yet
leſs, it would not ſo ſpeedily come to ſleep, as when it falleth on
a ſuperficies ſomewhat rugged. But tell me, Simplicius, when
the top turning round about it ſelf, in that manner, is let fall, why
doth it not move forwards in the air, as it doth afterwards when it
is upon the ground?
SIMP. Becauſe having air above it, and beneath, neither thoſe
parts, nor theſe have any where to touch, and not having more
caſion to go forward than backward, it falls perpendicularly.
SAGR. So then the onely reeling about its ſelf, without other
impetus, can drive the top forward, being arrived at the ground,
very nimbly. Now proceed we to what remains. That laſh,
which the driver tyeth to his Top-ſtick, and with which, winding
it about the top, he ſets it (i. e. makes it go) what effect hath it on
the ſaid top?
SIMP. It conſtrains it to turn round upon its toe, that ſo it may
free it ſelf from the Top-laſh.
SAGR. So then, when the top arriveth at the ground, it cometh
all the way turning about its ſelf, by means of the laſh. Hath it
not reaſon then to move in it ſelf more ſwiftly upon the ground,
than it did whilſt it was in the air?
SIMP. Yes doubtleſs; for in the air it had no other impulſe
than that of the arm of the projicient; and if it had alſo the
ing, this (as hath been ſaid) in the air drives it not forward at all:
but arriving at the floor, to the motion of the arm is added the
progreſſion of the reeling, whereby the velocity is redoubled. And
I know already very well, that the top skipping from the ground,
its velocity will deminiſh, becauſe the help of its circulation is
wanting; and returning to the Earth will get it again, and by that
1means move again faſter, than in the air. It onely reſts for me to
underſtand, whether in this ſecond motion on the Earth it move
more ſwiftly, than in the firſt; for then it would move in
tum, alwayes accelerating.
SAGR. I did not abſolutely affirm, that this ſecond motion is
more ſwift than the firſt; but that it may happen ſo to be
times.
SIMP. This is that, which I apprehend not, and which I
deſire to know.
SAGR. And this alſo you know of your ſelf. Therefore tell
me: When you let the top fall out of your hand, without
king it turn round (i. e. ſetting it) what will it do at its coming to
the ground?
SIMP. Nothing, but there lie ſtill.
SAGR. May it not chance, that in its fall to the ground it may
acquire a motion? Think better on it.
SIMP. Unleſſe we let it fall upon ſome inclining ſtone, as
children do playing at ^{*} Chioſa, and that falling ſide-wayes upon

the ſame, it do acquire the motion of turning round upon its toe,
wherewith it afterwards continueth to move progreſſively on the
floor, I know not in what other manner it can do any thing but
lie ſtill where it falleth.
* A Game in Italy,
which is, to glide
bullets down an
inclining ſtone,
&c.
SAGR. You ſee then that in ſome caſe it may acquire a new
revolution. When then the top jerked up from the ground, falleth
down again, why may it not caſually hit upon the declivity of
ſome ſtone fixed in the floor, and that hath an inclination that
way towards which it moveth, and acquiring by that ſlip a new
whirle over and above that conferred by the laſh, why may it
not redouble its motion, and make it ſwifter than it was at its
firſt lighting upon the ground?
SIMP. Now I ſee that the ſame may eaſily happen. And I
am thinking that if the top ſhould turn the contrary way, in
riving at the ground, it would work a contrary effect, that is,
the motion of the accidental whirl would retard that of the
jicient.
SAGR. And it would ſometimes wholly retard and ſtop it, in
caſe the revolution of the top were very ſwift. And from hence
riſeth the reſolution of that ſlight, which the more skilful Tennis
Players uſe to their advantage; that is, to gull their adverſary by
cutting (for ſo is their Phraſe) the Ball; which is, to return it
with a ſide Rachet, in ſuch a manner, that it doth thereby
quire a motion by it ſelf contrary to the projected motion, and ſo
by that means, at its coming to the ground, the rebound, which
if the ball did not turn in that manner, would be towards the
adverſary, giving him the uſual time to toſſe it back again, doth
1fail, and the ball runs tripping along the ground, or rebounds leſſe
than uſual, and breaketh the time of the return. Hence it is

that you ſee, thoſe who play at ^{*} Stool-ball, when they play in
a ſtony way, or a place full of. holes and rubs that make the ball
trip an hundred ſeveral wayes, never ſuffering it to come neer the
mark, to avoid them all, they do not trundle the ball upon the
ground, but throw it, as if they were to pitch a quait. But
cauſe in throwing the ball, it iſſueth out of the hand with ſome
roling conferred by the fingers, when ever the hand is under the
ball, as it is moſt commonly held; whereupon the ball in its lighting
on the ground neer to the mark, between the motion of the
jicient and that of the roling, would run a great way from the
ſame: To make the ball ſtay, they hold it artificially, with their
hand uppermoſt, and it undermoſt, which in its delivery hath
a contrary twirl or roling conferred upon it by the fingers, by
means whereof in its coming to the ground neer the mark it ſtays
there, or runs very very little forwards. But to return to our
principal problem which gave occaſion for ſtarting theſe others; I
ſay it is poſſible that a perſon carried very ſwiftly, may let a ball
drop out of his hand, that being come to the Earth, ſhall not
onely follow his motion, but alſo out-go it, moving with a
er velocity. And to ſee ſuch an effect, I deſire that the courſe
may be that of a Chariot, to which on the out-ſide let a
ning board be faſtened; ſo as that the neither part may be towards
the horſes, and the upper towards the hind Wheel. Now, if in
the Chariots full career, a man within it, let a ball fall gliding
long the declivity of that board, it ſhall in roling downward
quire a particular vertigo or turning, the which added to the
motion impreſſed by the Chariot, will carrie the ball along the
ground much faſter than the Chariot. And if one accommodate
another declining board over againſt it, the motion of the
riot may be qualified ſo, that the ball, gliding downwards along
the board, in its coming to the ground ſhall reſt immoveable,
and alſo ſhall ſometimes run the contrary way to the Chariot. But
we are ſtrayed too far from the purpoſe, therefore if Simplicius
be ſatisfied with the reſolution of the firſt argnment againſt the
Earths mobility, taken from things falling perpendicularly, we
may paſſe to the reſt
*A Game in Italy,
wherein they ſtrive
who ſhall trundle
or throw a wooden
bowle neereſt to an
aſſigned mark.
SALV. The digreſſions made hitherto, are not ſo alienated
from the matter in hand, as that one can ſay they are wholly
ſtrangers to it. Beſides theſe argumentations depend on thoſe
things that ſtart up in the fancy not of one perſon, but of three,
that we are: And moreover we diſcourſe for our pleaſure, nor
are we obliged to that ſtrictneſſe of one who ex profeſſo treateth
methodically of an argument, with an intent to publiſh the ſame.
1I will not conſent that our Poem ſhould be ſo confined to that
unity, as not to leave us fields open for Epſody's, which every
ſmall connection ſhould ſuffice to introduce; but with almoſt as
much liberry as if we were met to tell ſtories, it ſhall be lawful
for me to ſpeak, what ever your diſcourſe brings into my mind.
SAGR. I like this motion very well; and ſince we are at this
liberty, let me take leave, before we paſſe any farther to ask of
you Salviatus, whether you did ever conſider what that line may
be that is deſcribed by the grave moveable naturally falling down
from the top of a Tower; and if you have reflected on it, be
pleaſed to tell me what you think thereof.
SALV. I have ſometimes conſidered of it, and make no
ſtion, that if one could be certain of the nature of that motion
wherewith the grave body deſcendeth to approach the centre of
the Terreſtrial Globe, mixing it ſelf afterwards with the common
circular motion of the diurnal converſion; it might be exactly
found what kind of line that is, that the centre of gravity of the
moveable deſcribeth in thoſe two motions.
SAGR. Touching the ſimple motion towards the centre
pendent on the gravity, I think that one may confidently,
out error, believe that it is by a right line, as it would be, were
the Earth immoveable.
SALV. As to this particular, we may not onely believe it, but
experience rendereth us certain of the ſame.
SAGR. But how doth experience aſſure us thereof, if we
ver ſee any motions but ſuch as are compoſed of the two, circular
and deſcending.
SALV. Nay rather Sagredus we onely ſee the ſimple motion of
deſcent; ſince that other circular one common to the Earth, the
Tower and our ſelves remains imperceptible, and as if it never
were, and there remaineth perceptible to us that of the ſtone,
ly not participated by us, and for this, ſenſe demonſtrateth that
it is by a right line, ever parallel to the ſaid Tower, which is
built upright and perpendicular upon the Terreſtrial ſurface.
SAGR. You are in the right; and this was but too plainly
monſtrated to me even now, ſeeing that I could not remember ſo
eaſie a thing; but this being ſo manifeſt, what more is it that you
ſay you deſire, for underſtanding the nature of this motion
downwards?
SALV. It ſufficeth not to know that it is ſtreight, but its
ſite to know whether it be uniform, or irregular; that is,
ther it maintain alwayes one and the ſame velocity, or elſe goeth
retarding or accelerating.
SAGR. It is already clear, that it goeth continually
rating.
1
SALV. Neither doth this ſuffice, but its requiſite to know
cording to what proportion ſuch accelleration is made; a
blem, that I believe was never hitherto underſtood by any
loſopher or Mathematician; although Philoſophers, and
larly the Peripateticks, have writ great and entire Volumes,
touching motion.
SIMP. Philoſophers principally buſie themſelves about
ſals; they find the definitions and more common ſymptomes,
mitting certain ſubtilties and niceties, which are rather
ſities to the Mathematicians. And Aristotle did content himſelf
to deſine excellently what motion was in general; and of the
cal, to ſhew the principal qualities, to wit, that one is natural,
another violent; one is ſimple, another compound; one is
equal, another accellerate; and concerning the accelerate,
tents himſelf to give the reaſon of acceleration, remitting the
finding out of the proportion of ſuch acceleration, and other
particular accidents to the Mechanitian, or other inferiour
Artiſt.
SAGR. Very well Simplicius. But you Salviatus, when you
deſcend ſometimes from the Throne of Peripatetick Majeſty,
have you ever thrown away any of your hours in ſtudying to find
this proportion of the acceleration of the motion of deſcending
grave bodies?
SALV. There was no need that I ſhould ſtudy for it, in regard
that the Academick our common friend, heretofore ſhewed me a
Treatiſe of his ^{*} De Motu, where this, and many other

dents were demonſtrated. But it would be too great a digreſſion,
if for this particular, we ſhould interrupt our preſent diſcourſe,
(which yet it ſelf is alſo no better than a digreſſion) and make as
the Saying is, a Comedy within a Comedy.
This is that
cellent tract which
we give the firſt
place in our ſecond
Volume.
SAGR. I am content to excuſe you from this narration for the
preſent, provided that this may be one of the Propoſitions
ved to be examined amongſt the reſt in another particular meeting,
for that the knowledg thereof is by me very much deſired; and
in the mean time let us return to the line deſcribed by the grave
body in its fall from the top of the Tower to its baſe.
SALV. If the right motion towards the centre of the Earth was
uniforme, the circular towards the Eaſt being alſo uniforme, you
would ſee compoſed of them both a motion by a ſpiral line, of
that kind with thoſe defined by Archimedes in his Book Dc
libus; which are, when a point moveth uniformly upon a right
line, whileſt that line in the mean time turneth uniformly about
one of its extreme points fixed, as the centre of his gyration.
But becauſe the right motion of grave bodies falling, is
ally accelerated, it is neceſſary, that the line reſulting of the
1compoſition of the two motions do go alwayes receding with
greater and greater proportion from the circumference of that
cle, which the centre of the ſtones gravity would have deſigned,
if it had alwayes ſtaid upon the Tower; it followeth of neceſſity
that this receſſion at the firſt be but little, yea very ſinall, yea,
more, as ſmall as can be imagined, ſeeing that the deſcending
grave body departing from reſt, that is, from the privation of
motion, towards the bottom and entring into the right motion
downwards, it muſt needs paſſe through all the degrees of
ty, that are betwixt reſt, and any aſſigned velocity; the which
degrees are infinite; as already hath been at large diſcourſed and
proved.
It being ſuppoſed therefore, that the progreſſe of the
ration being after this manner, and it being moreover true, that
the deſcending grave body goeth to terminate in the centre of the
Earth, it is neceſſary that the line of its mixt motion be ſuch, that

it go continually receding with greater and greater proportion
from the top of the Tower, or to ſpeak more properly, from
the circumference of the circle deſcribed by the top of the Tower,
by means of the Earths converſion; but that ſuch receſſions be
leſſer and leſſer in infinitum; by how much the moveable finds it
ſelf to be leſſe and leſſe removed from the firſt term where it
reſted. Moreover it is neceſſary, that this line of the
ed motion do go to terminate in the centre of the Earth. Now
having preſuppoſed theſe two things, I come to deſcribe about
the centre A [in Fig. 1. of this ſecond Dialogue;] with the ſemi­
diameter A B, the circle B I, repreſenting to me the Terreſtrial
Globe, and prolonging the ſemidiameter A B to C, I have
ſcribed the height of the Tower B C; the which being carried
about by the Earth along the circumference B I, deſcribeth with
its top the arch C D: Dividing, in the next place, the line C A
in the middle at E; upon the centre E, at the diſtance E C, I
ſcribe the ſemicircle C I A: In which, I now affirm, that it is very
probable that a ſtone falling from the top of the Tower C, doth
move, with a motion mixt of the circular, which is in common,
and of its peculiar right motion. If therefore in the circumference
C D, certain equal parts C F, F G, G H, H L, be marked, and
from the points F, G, H, L, right lines be drawn towards the
centre A, the parts of them intercepted between the two
cumferences C D and B I, ſhall repreſent unto us the ſame
Tower C B, tranſported by the Terreſtrial Globe towards D I;
in which lines the points where they come to be interſected by the
arch of the ſemicircle C I, are the places by whichfrom time to
time the falling ſtone doth paſſe; which points go continually
with greater and greater proportion receding from the top of the
1Tower. And this is the cauſe why the right motion made along
the ſide of the Tower appeareth to us more and more accelerate.
It appeareth alſo, how by reaſon of the infinite acuteneſſe of
the contact of thoſe two circles D C, C I, the receſſion of the
cadent moveable from the circumference C F D; namely, from
the top of the Tower, is towards the beginning extream ſmall,
which is as much as if one ſaid its motion downwards is very ſlow,
and more and more ſlow in infinitum, according to its vicinity to
the term C, that is to the ſtate of reſt. And laſtly it is ſeen how
in the end this ſame motion goeth to terminate in the centre of the
Earth A.
The line
bed by a moveable
in its natural
ſcent, the motion
of the Earth
bout its own centre
being preſuppoſed,
would probably be
the circumference
of a circle.
SAGR. I underſtand all this very well, nor can I perſwade my
ſelf that the falling moveable doth deſcribe with the centre of its
gravity any other line, but ſuch an one as this.
SALV. But ſtay a little Sagredus, for I am to acquaint you
alſo with three Obſervations of mine, that its poſſible will not

pleaſe you. The firſt of which is, that if we do well conſider, the
moveable moveth not really with any more than onely one motion
ſimply circular, as when being placed upon the Tower, it moved
with one ſingle and circular motion. The ſecond is yet more

ſant; for, it moveth neither more nor leſſe then if it had ſtaid
tinually upon the Tower, being that to the arches C F, F G, G H,
&c. that it would have paſſed continuing alwayes upon the Tower,
the arches of the circumference C I are exactly equal, anſwering
under the ſame C F, F G, G H, &c. Whence followeth the third

wonder, That the true and real motion of the ſtone is never
lerated, but alwayes even and uniforme, ſince that all the equal
ches noted in the circumference C D, and their reſpondent ones
marked in the circumference C I, are paſt in equal times; ſo that
we are left at liberty to ſeek new cauſes of acceleration, or of
ther motions, ſeeing that the moveable, as well ſtanding upon the
Tower, as deſcending thence, alwayes moveth in the ſame faſhion,
that is, circularly, with the ſame velocity, and with the ſame
formity. Now tell me what you think of this my fantaſtical
jecture.
A moveable
ting from the top of
the Tower, moveth
in the
rence of a circle.
It moveth neither
more nor leſſe, than
if it had ſtaid
wayes there.
It moveth with
an uniform, not
an accelerate
tion.
SAGR. I muſt tell you, that I cannot with words ſufficiently
expreſſe how admirable it ſeemeth to me; and for what at
ſent offereth it ſelf to my underſtanding, I cannot think that the
buſineſs happeneth otherwiſe; and would to God that all the
demonſtrations of Philoſophers were but half ſo probable as this.
However for my perfect ſatisfaction I would gladly hear how you
prove thoſe arches to be equal.
SALV. The demonſtration is moſt eaſie. Suppoſe to your ſelf
a line drawn from I to E. And the Semidiameter of the circle CD,
that is, the line C A, being double the Semidiameter C E of the
1circle C I, the circumference ſhall be double to the circumference,
and every arch of the greater circle double to every like arch of
the leſſer; and conſequently, the half of the arch of the greater
circle, equal to the whole arch of the leſſe. And becauſe the
gle C E I made in the centre E of the leſſer circle, and which
ſteth upon the arch C I, is double the angle C A D, made in the
centre A of the greater circle, to which the arch C D ſubtendeth;
therefore the arch C D is half of the arch of the greater circle like
to the arch C I, and therefore the two arches C D and C I are
qual; and in the ſame manner we may demonſtrate of all their
parts. But that the buſineſs, as to the motion of deſcending grave
bodies, proceedeth exactly thus, I will not at this time affirm; but
this I will ſay, that if the line deſcribed by the cadent moveable
be not exactly the ſame with this, it doth extream neerly reſemble
the ſame.
SAGR. But I, Salviatus, am juſt now conſidering another

ticular very admirable; and this it is; That admitting theſe
ſiderations, the right motion doth go wholly ^{*} mounting, and that

Nature never makes uſe thereof, ſince that, even that that uſe,
which was from the beginning granted to it, which was of
cing the parts of integral bodies to their place, when they were
ſeparated from their whole, and therefore conſtituted in a
ved diſpoſition, is taken from it, and aſſigned to the circular
motion.
Right motion
ſeemeth wholly
cluded in nature.
* Vadia del tutto a
monte, rendered in
the Latixe
no peſſum eat.
SALV. This would neceſſarily follow, if it were concluded
that the Terreſtrial Globe moveth circularly; a thing, which I
pretend not to be done, but have onely hitherto attempted, as I
ſhall ſtill, to examine the ſtrength of thoſe reaſons, which have
been alledged by Philoſophers to prove the immobility of the
Earth, of which this firſt taken from things falling
larly, hath begat the doubts, that have been mentioned; which
I know not of what force they may have ſeemed to Simplicius;
and therefore before I paſſe to the examination of the remaining
arguments, it would be convenient that he produce what he hath
to reply to the contrary.
SIMP. As to this firſt, I confeſſe indeed that I have heard
ſundry pretty notions, which I never thought upon before, and
in regard they are new unto me, I cannot have anſwers ſo ready
for them, but this argument taken from things falling
cularly, I eſteem it not one of the ſtrongeſt proofs of the
lity of the Earth; and I know not what may happen touching the
ſhots of great Guns, eſpecially thoſe aimed contrary to the
nal motion.
SAGR. The flying of the birds as much puzzleth me as the
objection of the Gun-ſhot, and all the other experiments above
1alledged. For theſe birds which at their pleaſure flie
wards and backwards, and wind to and again in a thouſand
faſhions, and, which more importeth, lie whole hours upon the
wing, theſe I ſay do not a little poſe me, nor do I ſee, how
mongſt ſo many circumgyrations, they ſhould not loſe the motion
of the Earth, and how they ſhould be able to keep pace with
ſo great a velocity as that which they ſo far exceed with their flight.
SALV. To ſpeak the truth, your ſcruple is not without reaſon,
and its poſſible Copernicus himſelf could not find an anſwer for it,
that was to himſelf entirely ſatisfactory; and therefore haply paſt
it over in ſilence albeit he was, indeed, very brief in examining
the other allegations of his adverſaries, I believe through his
height of wit, placed on greater aud ſublimer contemplations,
like as Lions are not much moved at the barking of little Dogs.
We will therefore reſerve the inſtance of birds to the laſt place,
and for the preſent, ſee if we can give Simplicius ſatisfaction in
the others, by ſhewing him in our wonted manner, that he
ſelf hath their anſwers at hand, though upon firſt thoughts he doth
not diſcover them. And to begin with the ſhots made at randome,
with the ſelf ſame piece, powder, and ball, the one towards the Eaſt,
the other towards the Weſt, let him tell me what it is that perſwades
him to think that the Range towards the Weſt (if the diurnal
verſion belonged to the Earth) ought to be much longer than that
towards the
The reaſon why
a Gun ſhould ſiem
to carry farther
wards the Weſt
than towards the
Eaſt.
SIMP. I am moved ſo to think; becauſe in the ſhot made
wards the Eaſt, the ball whil'ſt it is out of the piece, is
ed by the ſaid piece, the which being carried round by the Earth,
runneth alſo with much velocity towards the ſame part,
upon the fall of the ball to the ground, cometh to be but little
diſtant from the piece. On the contrary in the ſhot towards the
Weſt, before that the ball falleth to the ground, the piece is
tired very far towards the Eaſt, by which means the ſpace
tween the ball and the piece, that is Range, will appear longer
than the other, by how much the piece, that is the Earth, had
run in the time that both the bals were in the air.
SALV. I could wiſh, that we did know ſome way to make an
experiment correſponding to the motion of theſe projects, as that
of the ſhip doth to the motion of things perpendicularly falling
from on high; and I am thinking how it may be done.
The experiment
of a running
riot to find out the
difference of
ges.
SAGR. I believe, that it would be a very oppoſite proof, to
take an open Chariot, and to accomodate therein a ^{*}Stock-bow
at half elevation, to the end the flight may prove the greateſt

that my be, and whil'ſt the horſes ſhall run, to ſhoot firſt towards
the part whither you drive, and then another backwards towards
the contrary part, cauſing ſome one to mark diligently where
the Chariot was in that moment f time when the ſhaft came to
1the ground, as well in the one ſhot as in the other: for thus you
may ſee exactly how much one ſhaft flew farther than the other.
* Baleſtrone da
zoni.
SIMP. In my thoughts this experiment is very proper: and I
do not doubt but that the flight, that is, the ſpace between the
ſhaft and the place where the chariot was at the ſhafts fall, will be
leſs by much when one ſhooteth towards the chariots courſe, than
when one ſhooteth the contrary way. For an example, let the
flight of it ſelf be three hundred yards, and the courſe of the
riot in the time whilſt the ſhaft ſtayeth in the air, an hundred
yards, therefore ſhooting towards the courſe, of the three hundred
yards of the flight, the chariot will have gone one hundred; ſo
then at the ſhafts coming to the ground, the ſpace between it and
the chariot, ſhall be but two hundred yards onely; but on the
contrary, in the other ſhoot, the chariot running contrary to the
ſhaft, when the ſhaft ſhall have paſſed its three hundred yards, and
the chariot its other hundred the contrary way, the diſtance
poſing ſhall be found to be four hundred yards.
SALV. Is there any way to ſhoot ſo that theſe flights may be
equal?
SIMP. I know no other way, unleſs by making the chariot to
ſtand ſtill.
SALV. This we know; but I mean when the chariot runneth
in full carreer.
SIMP. In that caſe you are to draw the Bow higher in
ing forwards, and to ſlack it in ſhooting the contrary way.
SALV. Then you ſee that there is one way more. But how
much is the bow to be drawn, and how much ſlackened?
SIMP. In our caſe, where we have ſuppoſed that the bow
ried three hundred yards, it would be requiſite to draw it ſo, as
that it might carry four hundred, and in the other to ſlacken it ſo,
as that it might carry no more than two hundred. For ſo each
of the flights would be but three hundred in relation to the chariot,
the which, with its courſe of an hundred yards which it ſubſtracts
from the ſhoot of four hundred, and addeth to that of two
dred, would reduce them both to three hundred.
SALV. But what effect hath the greater or leſs intenſneſs of the
bow upon the ſhaft?
SIMP. The ſtiffer bow carrieth it with greater velocity, and the
weaker with leſs; and the ſame ſhaft flieth ſo much farther at one
time than another, with how much greater velocity it goeth out of
the tiller at one time, than another.
SALV. So that to make the ſhaft ſhot either way, to flie at
qual diſtance from the running chariot, it is requiſite, that if in the
firſt ſhoot of the precedent example, it goeth out of the tiller with
v. g. four degrees of velocity, that then in the other ſhoot it
1part but with two onely: but if the ſame bow be uſed, it always
receiveth thence three degrees.
SIMP. It doth ſo; and for this reaſon, ſhooting with the
ſame bow in the chariots courſe, the ſhoots cannot be equal.
SALV. I had forgot to ask, with what velocity it is ſuppoſed in
this particular experiment, that the chariot runneth.
SIMP. The velocity of the chariot muſt be ſuppoſed to be one
degree in compariſon to that of the bow, which is three,
SALV. Very right, for ſo computation gives it. But tell me,
when the chariot moveth, doth not all things in the ſame move
with the ſame velocity?
SIMP. Yes doubtleſs.
SALV. Then ſo doth the ſhaft alſo, and the bow, and the ſtring,
upon which the ſhaft is nock't.
SIMP. They do ſo.
SALV. Why then, in diſcharging the ſhaft towards the courſe
of the chariot, the bow impreſſeth its three degrees of velocity on
a ſhaft that had one degree of velocity before, by means of the
chariot which tranſported it ſo faſt towards that part; ſo that in
its going off it hath four degrees of velocity. On the contrary,
in the other ſhoot, the ſame bow conferreth its ſame three degrees
of velocity on a ſhaft that moveth the contrary way, with one
gree; ſo that in its departing from the bow-ſtring, it hath no more
left but onely two degrees of velocity. But you your ſelf have
already ſaid, that the way to make the ſhoots equal, is to cauſe
that the ſhaft be let flie the firſt time with four degrees of velocity,
and the ſecond time with two. Therefore without changing the
bow, the very courſe of the chariot is that which adjuſteth the

flights, and the experiment doth ſo repreſent them to any one who
is not either wilfully or naturally incapable of reaſon. Now
apply this diſcourſe to Gunnery, and you ſhall find, that whether the
Earth move or ſtand ſtill, the ſhots made with the ſame force, will
always curry equal ranges, to what part ſoever aimed. The error
of Ariſtotle, Ptolomey, Iycho, your ſelf, and all the reſt, is
ed upon that fixed and ſtrong perſuaſion, that the Earth ſtandeth
ſtill, which you have not judgment nor power to depoſe, no not
when you have a deſire to argue of that which would enſue,
ſuppoſing the Earth to move. And thus, in the other argument,
not conſidering that whil'ſt the ſtone is upon the Tower, it doth,
as to moving or not moving, the ſame that the Terreſtrial Globe
doth, becauſe you have concluded with your ſelf, that the Earth
ſtands ſtill, you always diſcourſe touching the fall of the ſtone, as
if it were to depart from reſt: whereas it behooveth to ſay, that
if the Earth ſtandeth ſtill, the ſtone departeth from reſt, and
ſcendeth perpendicularly; but if the Earth do move, the ſtone
1likewiſe moveth with like velocity, nor doth it depart from reſt,
but from a motion equal to that of the Earth, wherewith it
mixeth the ſupervenient motion of deſcent, and of thoſe two
poſeth a third which is tranſverſal or ſide-ways.
The ſolution of
the argument
ken from
Guns ſhot towards
the East & Weſt.
SIMP. But for Gods ſake, if it move tranſverſly, how is it that
I behold it to move directly and perpendicularly? This is no
ter than the denial of manifeſt ſenſe; and if we may not believe
ſenſe, at what other door ſhall we enter into diſquiſitions of
ſophy?
SALV. In reſpect to the Earth, to the Tower, and to our ſelves,
which all as one piece move with the diurnal motion together with
the ſtone, the diurnal motion is as if it never had been, and
eth inſenſible, imperceptible, and without any action at all; and
the onely motion which we can perceive, is that of which we
take not, that is the deſcent gliding along the ſide of the Tower:
You are not the firſt that hath felt great repugnance in
ding this non-operating of motion upon things to which it is
mon.
SAGR. Now I do remember a certain conceipt, that came one

day into my fancy, whilſt I ſailed in my voyage to Aleppo, whither
I went Conſul for our Countrey, and poſſibly it may be of ſome
uſe, for explaining this nullity of operation of common motion,
and being as if it never were to all the partakers thereof. And if
it ſtand with the good liking of Simplicius, I will reaſon with
him upon that which then I thought of by my ſelf alone.
A notable caſe
of Sagredus, to ſhew
the non-operating
of common motion.
SIMP. The novelty of the things which I hear, makes me not
ſo much a patient, as a greedy and curious auditor: therefore go
on.
SAGR. If the neb of a writing pen, that I carried along with
me in the ſhip, through all my navigation from Venice to ^{*} Scan-

deron, had had a facultie of leaving viſible marks of its whole
age, what ſigns, what marks, what lines would it have left?
* Aleſſandretta.
SIMP. It would have left a line diſtended from Venice thither,
not perfectly ſtreight, or to ſay better, diſtended in a perfect arch
of a circle, but in ſome places more, in ſome leſs curved, according
as the veſſel had gone more or leſs fluctuating; but this its
cting in ſome places a fathom or two to the right hand or to the
left, upwards or downwards, in a length of many hundred miles,
would have brought but little alteration to the intire tract of the
line, ſo that it would have been hardly ſenſible; and without any
conſiderable error, might have been called the part of a perfect
arch.
SAGR. So that the true and moſt exact motion of the neb of
my pen would have alſo been an arch of a perfect circle, if the
veſſels motion, the fluctuation of the billows ceaſing, had been
1calm and tranquill. And if I had continually held that pen in
my hand, and had onely moved it ſometimes an inch or two this
way or that way, what alteration ſhould I have made in that its
principal, and very long tract or ſtroke?
SIMP. Leſs than that which the declining in ſeveral places from
abſolute rectitude, but the quantity of a flea's eye makes in a right
line of a thouſand yards long.
SAGR. If a Painter, then, at our launching from the Port, had
began to deſign upon a paper with that pen, and continued his
work till he came to Scanderon, he would have been able to have
taken by its motion a perfect draught of all thoſe figures perfectly
interwoven and ſhadowed on ſeveral ſides with countreys,
ings, living creatures, and other things; albeit all the true, real,
and eſſential motion traced out by the neb of that pen, would
have been no other than a very long, but ſimple line: and as to
the proper operation of the Painter, he would have delineated the
ſame to an hair, if the ſhip had ſtood ſtill. That therefore of the
huge long motion of the pen there doth remain no other marks,
than thoſe tracks drawn upon the paper, the reaſon thereof is
cauſe the grand motion from Venice to Scanderon, was common to
the paper, the pen, and all that which was in the ſhip: but the petty
motions forwards and backwards, to the right, to the left,
municated by the fingers of the Painter unto the pen, and not to
the paper, as being peculiar thereunto, might leave marks of it ſelf
upon the paper, which did not move with that motion. Thus it
is likewiſe true, that the Earth moving, the motion of the ſtone in
deſcending downwards, was really a long tract of many hundreds
and thouſands of yards, and if it could have been able to have
lineated in a calm air, or other ſuperficies, the track of its courſe,
it would have left behind an huge long tranſverſe line. But that
part of all this motion which is common to the ſtone, the Tower,
and our ſelves, is imperceptible to us, and as if it had never been,
and that part onely remaineth obſervable, of which neither the
Tower nor we are partakers, which is in fine, that wherewith the
ſtone falling meaſureth the Tower.
SALV. A moſt witty conceipt to clear up this point, which was
not a little difficult to many capacities. Now if Simplicius will
make no farther reply, we may paſs to the other experiments, the
unfolding of which will receive no ſmall facility from the things
already declared.
SIMP. I have nothing more to ſay: and I was well-nigh
ported with that delineation, and with thinking how thoſe ſtrokes
drawn ſo many ways, hither, thither, upwards, downwards,
wards, backwards, and interwoven with thouſands of turnings, are
not eſſentially or really other, than ſmall pieces of one ſole line
1drawn all one way, and the ſame without any other alteration ſave
the declining the direct rectitude, ſometimes a very inſenſible
ter towards one ſide or another, and the pens moving its neb one
while ſofter, another while ſlower, but with very ſmall inequality.
And I think that it would in the ſame manner write a letter, and
that thoſe frollike penmen, who to ſhew their command of hand,
without taking their pen from the paper in one ſole ſtroke, with
infinite turnings draw a pleaſant knot, if they were in a boat that
did tide it along ſwiftly they would convert the whole motion
of the pen, which in reality is but one ſole line, drawn all towards
one and the ſame part, and very little curved, or declining from
perfect rectitude, into a knot or flouriſh. And I am much pleaſed
that S agredus hath helped me to this conceit: therefore let us go
on, for the hope of meeting with more of them, will make me the
ſtricter in my attention.
SAGR. If you have a curioſity to hear ſuch like ſubtilties, which

occurr not thus to every one, you will find no want of them,
cially in this particular of Navigation; and do you not think that a
witty conceit which I met with likewiſe in the ſame voyage, when I
obſerved that the maſt of the ſhip, without either breaking or
ing, had made a greater voyage with its round-top, that is with its
top-gallant, than with its foot; for the round top being more diſtant
from the centre of the Earth than the foot is, it had deſcribed the
arch of a circle bigger than the circle by which the foot had paſſed.
Subtilties
ently inſipid,
cally, ſpoken and
taken from a
tain Encyclopædia.
SIMP. And thus when a man walketh he goeth farther with
his head than with his feet.
SAGR. You have found out the matter your ſelf by help of
your own mother-wit: But let us not interrupt Salviatus.
SALV. It pleaſeth me to ſee Simplicius how he ſootheth up
himſelf in this conceit, if happly it be his own, and that he hath not
borrowed it from a certain little pamphlet of concluſions, where
there are a great many more ſuch fancies no leſs pleaſant & witty.
It followeth that we ſpeak of the peice of Ordinance mounted

pendicular to the Horizon, that is, of a ſhot towards our vertical
point, and to conclude, of the return of the ball by the ſame line
unto the ſame peice, though that in the long time which it is
parated from the peice, the earth hath tranſported it many miles
towards the Eaſt; now it ſeemeth, that the ball ought to fall a like
diſtance from the peice towards the Weſt; the which doth not
happen: therefore the peice without having been moved did ſtay
expecting the ſame. The anſwer is the ſame with that of the

ſtone falling from the Tower; and all the fallacy, and
on conſiſteth in ſuppoſing ſtill for true, that which is in queſtion;
for the Opponent hath it ſtill fixed in his conceit that the
ball departs from its reſt, being diſcharged by the fire
1from the piece; and the departing from the ſtate of reſt, cannot
be, unleſſe the immobility of the Terreſtrial Globe be
ſed, which is the concluſion of that was in diſpute; Therefore,
I reply, that thoſe who make the Earth moveable, anſwer, that
the piece, and the ball that is in it, partake of the ſame motion
with the Earth; nay that they have this together with her from
nature; and that therefore the ball departs in no other manner
from its quieſcence, but conjoyned with its motion about the
tre, the which by its projection upwards, is neither taken away,
nor hindered; and in this manner following, the univerſal motion
of the Earth towards the Eaſt, it alwayes keepeth perpendicular
over the ſaid piece, as well in its riſe as in its return. And the
ſame you ſee to enſue, in making the experiment in a ſhip with
a bullet ſhot upwards perpendicularly with a Croſſe-bow, which
returneth to the ſame place whether the ſhip doth move, or ſtand

An inſtance
gainst the diurnal
motion of the earth,
taken from the ſhot
of a Peece of
nance
larly.
The anſwer to the
objection, ſhewing
the equivoke.
Another anſwer
to the ſame
on.
SAGR. This ſatisfieth very well to all; but becauſe that I have
ſeen that Simplicius taketh pleaſure with certain ſubtilties to
puzzle his companions, I will demand of him whether,
ſing for this time that the Earth ſtandeth ſtill, and the piece
cted upon it perpendicularly, directed to our Zenith, he do at all
queſtion that to be the true perpendicular ſhot, and that the ball
in departing, and in its return is to go by the ſame right line,
ſtill ſuppoſing all external and accidental impediments to be
moved?
SIMP. I underſtand that the matter ought to ſucceed exactly
in that manner.
SAGR. But if the piece were placed, not perpendicularly, but
inclining towards ſome place, what would the motion of the ball
be? Would it go haply, as in the other ſhot, by the
cular line, and return again by the ſame?
SIMP. It would not ſo do; but iſſuing out of the piece, it
would purſue its motion by a right line which prolongeth the
rect perpendicularity of the concave cylinder of the piece, unleſſe
ſo far as its own weight would make it decline from that erection
towards the Earth.
SAGR. So that the mounture of the cylinder is the regulator of
the motion of the ball, nor doth it, or would it move out of that
line, if its own gravity did not make it decline downwards. And

therefore placing the cylinder perpendicularly, and ſhooting the
ball upwards, it returneth by the ſame right line downwards;
cauſe the motion of the ball dependent on its gravity is
ward, by the ſame perpendicular. The journey therefore of the
ball out of the piece, continueth or prolongeth the rectitude or
perpendicularity of that ſmall part of the ſaid journey, which it
made within the ſaid piece; is it not ſo?
1
Projects
nue their motion
by the right line
that followeth the
direction of the
motion, made
gether with the
projicient, whil'ſt
they were conjoin'd
therewith.
SIMP. So it is, in my opinion.
SAGR. Now imagine the cylinder to be erected, and that the
Earth doth revolve about with a diurnal motion, carrying the
piece along with it, tell me what ſhall be the motion of the ball
within the cylinder, having given fire?
SIMP. It ſhall be a ſtreight and perpendicular motion, the
der being erected perpendicularly.
SAGR. Conſider well what you ſay: for I believe that it will
not be perpendicular. It would indeed be perpendicular, if the
Earth ſtood ſtill, for ſo the ball would have no other motion but
that proceeding from the fire. But in caſe the Earth turns round,

the ball that is in the piece, hath likewiſe a diurnal motion, ſo
that there being added to the ſame the impulſe of the fire, it
veth from the breech of the piece to the muzzle with two motions,
from the compoſition whereof it cometh to paſſe that the motion
made by the centre of the balls gravity is an inclining line. And
for your clearer underſtanding the ſame, let the piece A C [in
Fig. 2.] be erected, and in it the ball B; it is manifeſt, that the
piece ſtanding immoveable, and fire being given to it, the ball
will make its way out by the mouth A, and with its centre,
ſing thorow the the piece, ſhall have deſcribed the perpendicular
line B A, and it ſhall purſue that rectitude when it is out of the
piece, moving toward the Zenith. But in caſe the Earth ſhould
move round, and conſequently carry the piece along with it, in
the time that the ball driven out of the piece ſhall move along
the cylinder, the piece being carried by the Earth, ſhall paſſe
to the ſituation D E, and the ball B, in going off, would be at
the corniſh D, and the motion of the bals centre, would have
been according to the line B D, no longer perpendicular, but
clining towards the Eaſt; and the ball (as hath been concluded)
being to continue its motion through the air, according to the
direction of the motion made in the piece, the ſaid motion ſhall
continue on according to the inclination of the line B D, and ſo
ſhall no longer be perpendicular, but inclined towards the Eaſt,
to which part the piece doth alſo move; whereupon the ball may
follow the motion of the Eerth, and of the piece. Now Simplicius,
you ſee it demonſtrated, that the Range which you took to be
perpendicular, is not ſo.
The revolution
of the Earth
poſed, the ball in
the piece erected
perpendicularly,
doth not move by a
perpendicular, but
an inclined line.
SIMP. I do not very well underſtand this buſineſs; do you,
Salviatus?
SALV. I apprehend it in part; but I have a certain kind of
ſcruple, which I wiſh I knew how to expreſs. It ſeems to me, that
according to what hath been ſaid, if the Piece be erected
dicular, and the Earth do move, the ball would not be to fall, as
Ariſtotle and Tycho will have it, far from the Piece towards the
1Weſt, nor as you would have it, upon the Piece, but rather far
diſtant towards the Eaſt. For according to your explanation, it
would have two motions, the which would with one conſent carry
it thitherward, to wit, the common motion of the Earth, which
carrieth the Piece and the ball from C A towards E D; and the
fire which carrieth it by the inclined line B D, both motions
wards the Eaſt, and therefore they are ſuperiour to the motion of
the Earth.
SAGR. Not ſo, Sir. The motion which carrieth the ball
wards the Eaſt, cometh all from the Earth, and the fire hath no
part at all therein: the motion which mounteth the ball upwards,
is wholly of fire, wherewith the Earth hath nothing to do. And
that it is ſo, if you give not fire, the ball will never go out of the
Piece, nor yet riſe upwards a hairs breadth; as alſo if you make
the Earth immoveable, and give fire, the ball without any
nation ſhall go perpendicularly upwards. The ball therefore
ving two motions, one upwards, and the other in gyration, of both
which the tranſverſe line B D is compounded, the impulſe upward
is wholly of fire, the circular cometh wholly from the Earth, and
is equal to the Earths motion: and being equal to it, the ball
maintaineth it ſelf all the way directly over the mouth of the
Piece, and at laſt falleth back into the ſame: and becauſe it
ways obſerveth the erection of the Piece, it appeareth alſo
nually over the head of him that is near the Piece, and therefore
it appeareth to mount exactly perpendicular towards our Zenith,
or vertical point.
SIMP. I have yet one doubt more remaining, and it is, that in
regard the motion of the ball is very ſwift in the Piece, it ſeems
not poſſible, that in that moment of time the tranſpoſition of the
Piece from C A to A D ſhould confer ſuch an inclination upon
the tranſverſe line C D, that by means thereof, the ball when it
cometh afterwards into the air ſhould be able to follow the courſe
of the Earth.
SAGR. You err upon many accounts; and firſt, the inclination
of the tranſverſe line C D, I believe it is much greater than you
take it to be, for I verily think that the velocity of the Earths
tion, not onely under the Equinoctial, but in our paralel alſo, is
greater than that of the ball whilſt it moveth in the Piece; ſo that
the interval C E would be abſolutely much bigger than the whole
length of the Piece, and the inclination of the tranſverſe line
ſequently bigger than half a right angle: but be the velocity of
the Earth more, or be it leſs, in compariſon of the velocity of the
fire, this imports nothing; for if the velocity of the Earth be ſmall,
and conſequently the inclination of the tranſverſe line be little
alſo; there is then alſo need but of little inclination to make the
1ball ſuſpend it ſelf in its range directly over the Piece. And in a
word, if you do but attentively conſider, you will comprehend,
that the motion of the Earth in transferring the Piece along with
it from C A to E D, conferreth upon the tranſverſe line C D, ſo
much of little or great inclination, as is required to adjuſt the
range to its perpendicularity. But you err, ſecondly, in that you
referr the faculty of carrying the ball along with the Earth to the
impulſe of the fire, and you run into the ſame error, into which
Salviatus, but even now ſeemed to have fallen; for the faculty
of following the motion of the Earth, is the primary and perpetual
motion, indelibly and inſeparably imparted to the ſaid ball, as to a
thing terreſtrial, and that of its own nature doth and ever ſhall
poſſeſs the ſame.
SALV. Let us yield, Simplicius, for the buſineſs is juſt as he

ſaith. And now from this diſcourſe let us come to underſtand the
reaſon of a Venatorian Problem, of thoſe Fowlers who with their
guns ſhoot a bird flying; and becauſe I did imagine, that in regard
the bird flieth a great pace, therefore they ſhould aim their ſhot far
from the bird, anticipating its flight for a certain ſpace, and more
or leſs according to its velocity and the diſtance of the bird, that
ſo the bullet haſting directly to the mark aimed at, it might come
to arrive at the ſelf ſame time in the ſame point with its motion,
and the bird with its flight, and by that means one to encounter
the other: and asking one of them, if their practiſe was not ſo
to do; He told me, no; but that the ſlight was very eaſie and
certain, and that they took aim juſt in the ſame manner as if they
had ſhot at a bird that did ſit ſtill; that is, they made the flying
bird their mark, and by moving their fowling-piece they followed
her, keeping their aim ſtill full upon her, till ſuch time as they let
fly, and in this manner ſhot her as they did others ſitting ſtill. It is
neceſſary therefore that that motion, though ſlow, which the
ing-piece maketh in turning and following after the flight of the
bird do communicate it ſelf to the bullet alſo, and that it be joyned
with that of the fire; ſo that the ball hath from the fire the
tion directly upwards, and from the concave Cylinder of the barrel
the declination according to the flight of the Bird, juſt as was ſaid
before of the ſhot of a Canon; where the ball receiveth from the
fire a virtue of mounting upwards towards the Zenith, and from
the motion of the Earth its winding towards the Eaſt, and of both
maketh a compound motion that followeth the courſe of the
Earth, and that to the beholder ſeemeth onely to go directly
wards, and return again downwards by the ſame line. The
ing therefore of the gun continually directed towards the mark,
maketh the ſhoot hit right, and that you may keep your gun
rected to the mark, in caſe the mark ſtands ſtill, you muſt alſo hold
1your gun ſtill; and if the mark ſhall move, the gun muſt be kept upon
the mark by moving. And upon this dependeth the proper anſwer

to the other argument taken from the ſhot of a Canon, at the
mark placed towards the South or North: wherein is alledged,
that if the Earth ſhould move, the ſhots would all range
ward of the mark, becauſe that in the time whilſt the ball, being
forc'd out of the Piece, goeth through the air to the mark, the ſaid
mark being carried toward the Eaſt, would leave the ball to the
Weſtward. I anſwer therefore, demanding whether if the
non be aimed true at the mark, and permitted ſo to continue, it
will conſtantly hit the ſaid mark, whether the Earth move or ſtand
ſtill? It muſt be replied, that the aim altereth not at all, for if
the mark doth ſtand ſtill, the Piece alſo doth ſtand ſtill, and if it,
being tranſported by the Earths motion, doth move, the Piece doth
alſo move at the ſame rate, and, the aim maintained, the ſhot
proveth always true, as by what hath been ſaid above, is
feſt.
The manner how
Fowlers ſhoot birds
flying.
The anſwer to
the objection tak n
from the ſhots of
great Guns made
towards the North
and South.
SAGR. Stay a little, I entreat you, Salviatus, till I have
pounded a certain conceit touching theſe ſhooters of birds flying,
whoſe proceeding I believe to be the ſame which you relate, and
believe the effect of hitting the bird doth likewiſe follow: but yet
I cannot think that act altogether conformable to this of ſhooting
in great Guns, which ought to hit as well when the piece and mark
moveth, as when they both ſtand ſtill; and theſe, in my opinion,
are the particulars in which they diſagree. In ſhooting with a
great Gun both it and the mark move with equal velocity, being
both tranſported by the motion of the Terreſtrial Globe: and
beit ſometimes the piece being planted more towards the Pole,
than the mark, and conſequently its motion being ſomewhat
er than the motion of the mark, as being made in a leſſer circle,
ſuch a difference is inſenſible, at that little diſtance of the piece
from the mark: but in the ſhot of the Fowler the motion of the
Fowling-piece wherewith it goeth following the bird, is very ſlow
in compariſon of the flight of the ſaid bird; whence me thinks it
ſhould follow, that that ſmall motion which the turning of the
Birding-piece conferreth on the bullet that is within it, cannot,
when it is once gone forth of it, multiply it ſelf in the air, untill it
come to equal the velocity of the birds flight, ſo as that the ſaid bullet
ſhould always keep direct upon it: nay, me thinketh the bird
would anticipate it and leave it behind. Let me add, that in this
act, the air through which the bullet is to paſs, partaketh not of the
motion of the bird: whereas in the caſe of the Canon, both it,
the mark, and the intermediate air, do equally partake of the
mon diurnal motion. So that the true cauſe of the Marks-man
his hitting the mark, as it ſhould ſeem, moreover and beſides the
1following the birds flight with the piece, is his ſomewhat
ting it, taking his aim before it; as alſo his ſhooting (as I believe)
not with one bullet, but with many ſmall balls (called ſhot) the
which ſcattering in the air poſſeſs a great ſpace; and alſo the
treme velocity wherewith theſe ſhot, being diſcharged from the
Gun, go towards the bird.
SALV. See how far the winged wit of Sagredus anticipateth,
and out-goeth the dulneſs of mine; which perhaps would have

light upon theſe diſparities, but not without long ſtudie. Now
turning to the matter in hand, there do remain to be conſidered
by us the ſhots at point blank, towards the Eaſt and towards the
Weſt; the firſt of which, if the Earth did move, would always
happen to be too high above the mark, and the ſecond too low;
foraſmuch as the parts of the Earth Eaſtward, by reaſon of the
urnal motion, do continually deſcend beneath the tangent paralel
to the Horizon, whereupon the Eaſtern ſtars to us appear to aſcend;
and on the contrary, the parts Weſtward do more and more
cend, whereupon the Weſtern ſtars do in our ſeeming deſcend:
and therefore the ranges which are leveled according to the ſaid
tangent at the Oriental mark, (which whilſt the ball paſſeth
along by the tangent deſcendeth) ſhould prove too high, and the
Occidental too low by means of the elevation of the mark, whilſt
the ball paſſeth along the tangent. The anſwer is like to the reſt:
for as the Eaſtern mark goeth continually deſcending, by reaſon
of the Earths motion, under a tangent that continueth
able; ſo likewiſe the piece for the ſame reaſon goeth continually
inclining, and with its mounture purſuing the ſaid mark: by
which means the ſhot proveth true.
The anſwer to the
Argument taken
from the ſhots at
point blanck
wards the Eaſt &
Weſt.
But here I think it a convenient opportunity to give notice of

certain conceſſions, which are granted perhaps over liberally by
the followers of Copernicus unto their Adverſaries: I mean of
yielding to them certain experiments for ſure and certain, which
yet the Adverſaries themſelves had never made tryal of: as for
example, that of things falling from the round-top of a ſhip whilſt
it is in motion, and many others; amongſt which I verily believe,
that this of experimenting whether the ſhot made by a Canon
wards the Eaſt proveth too high, and the Weſtern ſhot too low,
is one: and becauſe I believe that they have never made tryal
thereof, I deſire that they would tell me what difference they
think ought to happen between the ſaid ſhots, ſuppoſing the Earth
moveable, or ſuppoſing it moveable; and let Simplieius for this
time anſwer for them.
The followers of
Copernicus too
freely admit
tain propoſitions for
true, which are
very doubtfull.
SIMP. I will not undertake to anſwer ſo confidently as another
more intelligent perhaps might do; but ſhall ſpeak what thus upon
the ſudden I think they would reply; which is in effect the ſame
1with that which hath been ſaid already, namely, that in caſe the
Earth ſhould move, the ſhots made Eaſtward would prove too
high, &c. the ball, as it is probable, being to move along the
gent.
SALV. But if I ſhould ſay, that ſo it falleth out upon triall,
how would you cenſure me?
SIMP. It is neceſſary to proceed to experiments for the
ving of it.
SALV. But do you think, that there is to be found a Gunner ſo
skilful, as to hit the mark at every ſhoot, in a diſtance of v.g. five
hundred paces?
SIMP. No Sir; nay I believe that there is no one, how good a
marks-man ſoever that would promiſe to come within a pace of
the mark,
SALV. How can we then, with ſhots ſo uncertain, aſſure our
ſelves of that which is in diſpute?
SIMP. We may be aſſured thereof two wayes; one, by
king many ſhots; the other, becauſe in reſpect of the great
city of the Earths motion, the deviation from the mark would in
my opinion be very great.
SALV. Very great, that is more than one pace; in regard that
the varying ſo much, yea and more, is granted to happen ordinarily
even in the Earths mobility.
SIMP. I verily believe the variation from the mark would be
more than
A Computation
how much the
ges of great ſhot
ought to vary from
the marke, the
Earths motion
ing granted.
SALV. Now I deſire that for our ſatisfaction we do make thus
in groſſe a ſlight calculation, if you conſent thereto, which will
ſtand us in ſtead likewiſe (if the computation ſucceed as I expect)
for a warning how we do in other occurrences ſuffer our ſelves, as
the ſaying is, to be taken with the enemies ſhouts, and ſurrender
up our belief to what ever firſt preſents it ſelf to our fancy. And
now to give all advantages to the Peripateticks and Tychonicks,
let us ſuppoſe our ſelves to be under the Equinoctial, there to ſhoot
a piece of Ordinance point blank Eaſtwards at a mark five
dred paces off. Firſt, let us ſee thus (as I ſaid) in a level, what
time the ſhot after it is gone out of the Piece taketh to arrive at
the mark; which we know to be very little, and is certainly no
more than that wherein a travailer walketh two ſteps, which alſo
is leſs than the ſecond of a minute of an hour; for ſuppoſing
that the travailer walketh three miles in an hour, which are nine
thouſand paces, being that an hour containes three thouſand, ſix
hundred ſecond minutes, the travailer walketh two ſteps and an
half in a ſecond, a ſecond therefore is more than the time of the
balls motion. And for that the diurnal revolution is twenty four
hours, the Weſtern horizon riſeth fifteen degrees in an hour, that
1is, fifteen firſt minutes of a degree, in one firſt minute of an hour;
that is, fifteen ſeconds of a degree, in one ſecond of an hour; and
becauſe one ſecond is the time of the ſhot, therefore in this time
the Weſtern horizon riſeth fifteen ſeconds of a degree, and ſo
much likewiſe the mark; and therefore fifteen ſeconds of that
cle, whoſe ſemidiameter is five hundred paces (for ſo much the
ſtance of the mark from the Piece was ſuppoſed.) Now let us
look in the table of Arches and Chords (ſee here is Copernicus his
book) what part is the chord of fifteen ſeconds of the
ter, that is, five hundred paces. Here you ſee the chord (or
tenſe) of a firſt minute to be leſs than thirty of thoſe parts, of
which the ſemidiameter is an hundred thouſand. Therefore the
chord of a ſecond minute ſhall be leſs then half of one of thoſe
parts, that is leſs than one of thoſe parts, of whichthe
ter is two hundred thouſand; and therefore the chord of fifteen
conds ſhall be leſs than fifteen of thoſe ſame two hundred thouſand
parts; but that which is leſs than (a) fifteen parts of two hun­

dred thouſand, is alſo more than that which is four centeſmes of
five hundred; therefore the aſcent of the mark in the time of the
balls motion is leſſe than four centeſmes, that is, than one twenty
fifth part of a pace; it ſhall be therefore (b) about two inches:
And ſo much conſequently ſhall be the variation of each Weſtern
ſhot, the Earth being ſuppoſed to have a diurnal motion. Now if I
ſhall tell you, that this variation (I mean of falling two inches ſhort
of what they would do in caſe the Earth did not move) upon

all doth happen in all ſhots, how will you convince me Simplicius,
ſhewing me by an experiment that it is not ſo? Do you not ſee
that it is impoſſible to confute me, unleſs you firſt find out a way
to ſhoot at a mark with ſo much exactneſſe, as never to miſſe an
hairs bredth? For whilſt the ranges of great ſhot conſiſt of
rent numbers of paces, as de facto they do, I will affirm that in
each of thoſe variations there is contained that of two inches
ſed by the motion of the Earth.
(a) That is, in
plainer termes the
fraction 15/200000, is
more than the
ction 4/50000, for
viding the
nators by their
minators, and the
firſt produceth
13333 1/3 the other
but 12500.
(b) It ſhall be
neer 2 2/5 inches,
counting the pace
to be Geometrical,
containing 5 foot.
SAGR. Pardon me, Salviatus, you are too liberal. For I would

tell the Peripateticks, that though every ſhot ſhould hit the very
centre of the mark, that ſhould not in the leaſt diſprove the motion
of the Earth. For the Gunners are ſo conſtantly imployed in
velling the ſight and gun to the mark, as that they can hit the ſame,
notwithſtanding the motion of the Earth. And I ſay, that if the
Earth ſhould ſtand ſtill, the ſhots would not prove true; but the
Occidental would be too low, and the Oriental too high: now let
Simplicius diſprove me if he can.
It is
ted with great
tilty, that the
Earths motion
poſed, Canon ſhot
ought not to vary
more than in reſt.
SALV. This is a ſubtilty worthy of Sagredus: But whether
this variation be to be obſerved in the motion, or in the reſt of the
Earth, it muſt needs be very ſmall, it muſt needs be ſwallowed up
1in thoſe very great ones which ſundry accidents continually

duce. And all this hath been ſpoken and granted on good grounds
to Simplicius, and only with an intent to advertiſe him how much
it importeth to be cautious in granting many experiments for true
to thoſe who never had tried them, but only eagerly alledged them
juſt as they ought to be for the ſerving their purpoſe: This is
ken, I ſay, by way of ſurpluſſage and Corollary to Simplicius, for

the real truth is, that as concerning theſe ſhots, the ſame ought
actly to befall aſwell in the motion as in the reſt of the Terreſtrial
Globe; as likewiſe it will happen in all the other experiments
that either have been or can be produced, which have at firſt bluſh
ſo mnch ſemblance of truth, as the antiquated opinion of the
Earths motion hath of equivocation.
It is requiſite to
be very cautious in
admitting
ments for true, to
thoſe who never
tried them.
Experiments and
arguments againſt
the Earths motion
ſeem ſo far
cluding, as they lie
hid under
vokes.
SAGR. As for my part I am fully ſatisfied, and very well
derſtand that who ſo ſhall imprint in his fancy this general
munity of the diurnal converſion amongſt all things Terreſtrial,
to all which it naturally agreeth, aſwell as in the old conceit of its
reſt about the centre, ſhall doubtleſſe diſcern the fallacy and
voke which made the arguments produced ſeem eoncluding.
There yet remains in me ſome hæſitancy (as I have hinted
fore) touching the flight of birds; the which having as it were an
animate faculty of moving at their pleaſure with a thouſand
tions, and to ſtay long in the Air ſeparated from the Earth, and
therein with moſt irregular windings to go fluttering to and again,
I cannot conceive how amongſt ſo great a confuſion of motions,
they ſhould be able to retain the firſt commune motion; and in
what manner, having once made any ſtay behind, they can get
it up again, and overtake the ſame with flying, and kcep pace
with the Towers and trees which hurry with ſo precipitant a courſe
towards the Eaſt; I ſay ſo precipitant, for in the great circle of
the Globe it is little leſſe than a thouſand miles an hour, whereof
the flight of the ſwallow I believe makes not fifty.
SALV. If the birds were to keep pace with the courſe of the
trees by help of their wings, they would oſ neceſſity flie very faſt;
and if they were deprived of the univerſal converſion, they would
lag as far behind; and their flight would ſeem as furious towards
the Weſt, and to him that could diſcern the ſame, it would
much exceed the flight of an arrow; but I think we could not be
able to perceive it, no more than we ſee a Canon bullet, whil'ſt
driven by the fury of the fire, it flieth through the Air: But the
truth is that the proper motion of birds, I mean of their flight,
hath nothing to do with the univerſal motion, to which it is
ther an help, nor an hinderance; and that which maintaineth
the ſaid motion unaltered in the birds, is the Air it ſelf, thorough
which they flie, which naturally following the Vertigo of the
1Earth, like as it carrieth the clouds along with it, ſo it tranſporteth
birds and every thing elſe which is pendent in the ſame; in ſo much
that as to the buſineſſe of keeping pace with the Earth, the birds
need take no care thereof, but for that work might ſleep
tually.
SAGR. That the Air can carry the clouds along with it, as
being matters eaſie for their lightneſſe to be moved and deprived
of all other contrary inclination, yea more, as being matters that
partake alſo of the conditions and properties of the Earth; I
prehend without any difficulty; but that birds, which as having
life, may move with a motion quite contrary to the diurnal, once
having ſurceaſed the ſaid motion, the Air ſhould reſtore them to
it, ſeems to me a little ſtrange, and the rather for that they are ſolid
and weighty bodies; and withal, we ſee; as hath been ſaid, ſtones
and other grave bodies to lie unmoved againſt the impetus of the
air; and when they ſuffer themſelves to be overcome thereby,
they never acquire ſo much velocity as the wind which carrieth
them.
SALV. We aſcribe not ſo little force, Sagredus, to the moved
Air, which is able to move and bear before it ſhips full fraught,
to tear up trees by the roots, and overthrow Towers when it
moveth ſwiftly; and yet we cannot ſay that the motion of the
Air in theſe violent operations is neer ſo violent, as that of the
diurnal revolution.
SIMP. You ſee then that the moved Air may alſo cotinue the
motion of projects, according to the Doctrine of Ariſtotle; and
it ſeemed to me very ſtrange that he ſhould have erred in this
particular.
SALV. It may without doubt, in caſe it could continue it ſelf,
but lik as when the wind ceaſing neither ſhips go on, nor trees are
blown down, ſo the motion in the Air not continuing after the
ſtone is gone out of the hand, and the Air ceaſing to move, it
followeth that it muſt be ſomething elſe beſides the Air that
keth the projects to move.
SIMP. But how upon the winds being laid, doth the ſhip ceaſe
to move? Nay you may ſee that when the wind is down, and
the ſails furl'd, the veſſel continueth to run whole miles.
SALV. But this maketh againſt your ſelf Simplicius, for that
the wind being laid that filling the ſails drove on the ſhip, yet
vertheleſſe doth it without help of the medium continue its
courſe.
SIMP. It might be ſaid that the water was the medium which
carried forward the ſhip, and maintain'd it in motion.
SALV. It might indeed be ſo affirmed, if you would ſpeak
quite contrary to truth; for the truth is, that the water, by
1ſon of its great reſiſtance to the diviſion made by the hull of the
ſhip, doth with great noiſe reſiſt the ſame; nor doth it permit it
of a great while to acquire that velocity which the wind would
confer upon it, were the obſtacle of the water removed.
haps Simplicius you have never conſidered with what fury the
water beſets a bark, whil'ſt it forceth its way through a ſtanding
water by help of Oars or Sails: for if you had ever minded that
effect, you would not now have produced ſuch an abſurdity.
And I am thinking that you have hitherto been one of thoſe who
to find out how ſuch things ſucceed, and to come to the
ledg of natural effects, do not betake themſelves to a Ship, a
Croſſe-bow, or a piece of Ordinance, but retire into their
dies, and turn over Indexes and Tables to ſee whether Aristotle
hath ſpoken any thing thereof, and being aſſured of the true
ſenſe of the Text, neither deſire nor care for knowing any

The great
city for which they
are much to be
vied who perſwade
themſelves that
they know every
thing.
SAGR. This is a great felicity, and they are to be much
vied for it. For if knowledg be deſired by all, and if to be wiſe,
be to think ones ſelf ſo, they enjoy a very great happineſſe, for
that they may perſwade themſelves that they know and underſtand
all things, in ſcorn of thoſe who knowing, that they underſtand
not what theſe think they underſtand, and conſequently ſeeking
that they know not the very leaſt particle of what is knowable,
kill themſelves with waking and ſtudying, and conſume their days
in experiments and obſervations. But pray you let us return to
our birds; touching which you have ſaid, that the Air being
ved with great velocity, might reſtore unto them that part of the
diurnal motion which amongſt the windings of their flight they
might have loſt; to which I reply, that the agitated Air ſeemeth
unable to confer on a ſolid and grave body, ſo great a velocity as
its own: And becauſe that of the Air is as great as that of the
Earth, I cannot think that the Air is able to make good the loſſe
of the birds retardation in flight.
SALV. Your diſcourſe hath in it much of probability, and to
ſtick at trivial doubts is not for an acute wit; yet nevertheleſſe the
probability being removed, I believed that it hath not a jot more
force than the others already conſidered and reſolved.
SAGR. It is moſt certain that if it be not neceſſatily
dent, its efficacy muſt needs be juſt nothing at all, for it is
onely when the concluſion is neceſſary that the opponent hath
thing to alledg on the contrary.
SALV. Your making a greater ſcruple of this than of the other
inſtances dependeth, if I miſtake not, upon the birds being
mated, and thereby enabled to uſe their ſtrength at pleaſure
gainſt the primary motion in-bred in terrene bodies: like as for
1example, we ſee them whil'ſt they are alive to fly upwards, a thing
altogether impoſſible for them to do as they are grave bodies;
whereas being dead they can onely fall downwards; and
fore you hold that the reaſons that are of force in all the kinds of
projects above named, cannot take place in birds: Now this is
very true; and becauſe it is ſo, Sagredus, that doth not appear
to be done in thoſe projects, which we ſee the birds to do. For if

from the top of a Tower you let fall a dead bird and a live one,
the dead bird ſhall do the ſame that a ſtone doth, that is, it ſhall
firſt follow the general motion diurnal, and then the motion of
deſcent, as grave; but if the bird let fall, be a live, what ſhall
hinder it, (there ever remaining in it the diurnal motion) from
ſoaring by help of its wings to what place of the Horizon it ſhall
pleaſe? and this new motion, as being peculiar to the bird, and
not participated by us, muſt of neceſſity be viſible to us; and if
it be moved by help of its wings towards the Weſt, what ſhall
hinder it from returning with a like help of its wings unto the
Tower. And, becauſe, in the laſt place, the birds wending its
flight towards the Weſt was no other than a withdrawing from
the diurnal motion, (which hath, ſupppoſe ten degrees of velocity)
one degree onely, there did thereupon remain to the bird whil'ſt
it was in its flight nine degrees of velocity, and ſo ſoon as it did
alight upon the the Earth, the ten common degrees returned to it,
to which, by flying towards the Eaſt it might adde one, and with
thoſe eleven overtake the Tower. And in ſhort, if we well
ſider, and more narrowly examine the effects of the flight of
birds, they differ from the projects ſhot or thrown to any part of
the World in nothing, ſave onely that the projects are moved by an
external projicient, and the birds by an internal principle. And

here for a final proof of the nullity of all the experiments before
alledged, I conceive it now a time and place convenient to
demonſtrate a way how to make an exact trial of them all.
Shut your ſelf up with ſome friend in the grand Cabbin between
the decks of ſome large Ship, and there procure gnats, flies, and
ſuch other ſmall winged creatures: get alſo a great tub (or
other veſſel) full of water, and within it put certain fiſhes; let
alſo a certain bottle be hung up, which drop by drop letteth forth
its water into another bottle placed underneath, having a narrow
neck: and, the Ship lying ſtill, obſerve diligently how thoſe ſmall
winged animals fly with like velocity towards all parts of the
bin; how the fiſhes ſwim indifferently towards all ſides; and how
the diſtilling drops all fall into the bottle placed underneath. And
caſting any thing towards your friend, you need not throw it with
more force one way then another, provided the diſtances be equal:
and leaping, as the ſaying is, with your feet cloſed, you will reach
1as far one way as another. Having obſerved all theſe particulars,
though no man doubteth that ſo long as the veſſel ſtands ſtill, they
ought to ſucceed in this manner; make the Ship to move with
what velocity you pleaſe; for (ſo long as the motion is uniforme,
and not fluctuating this way and that way) you ſhall not diſcern
any the leaſt alteration in all the forenamed effects; nor can you
gather by any of them whether the Ship doth move or ſtand ſtill.
In leaping you ſhall reach as far upon the floor, as before; nor for
that the Ship moveth ſhall you make a greater leap towards the
poop than towards the prow; howbeit in the time that you ſtaid
in the Air, the floor under your feet ſhall have run the contrary way
to that of your jump; and throwing any thing to your companion
you ſhall not need to caſt it with more ſtrength that it may reach
him, if he ſhall be towards the prow, and you towards the poop,
then if you ſtood in a contrary ſituation; the drops ſhall all diſtill
as before into the inferiour bottle and not ſo much as one ſhall
fall towards the poop, albeit whil'ſt the drop is in the Air, the Ship
ſhall have run many feet; the Fiſhes in their water ſhall not ſwim
with more trouble towards the fore-part, than towards the hinder
part of the tub; but ſhall with equal velocity make to the bait
placed on any ſide of the tub; and laſtly, the flies and gnats
ſhall continue their flight indifferently towards all parts; nor
ſhall they ever happen to be driven together towards the ſide of
the Cabbin next the prow, as if they were wearied with
lowing the ſwift courſe of the Ship, from which through their
ſuſpenſion in the Air, they had been long ſeparated; and if
burning a few graines of incenſe you make a little ſmoke,
you ſhall ſee it aſcend on high, and there in manner of a cloud
ſuſpend it ſelf, and move indifferently, not inclining more to one
ſide than another: and of this correſpondence of effects the cauſe
is for that the Ships motion is common to all the things contained
in it, and to the Air alſo; I mean if thoſe things be ſhut up in the
Cabbin: but in caſe thoſe things were above deck in the open Air,
and not obliged to follow the courſe of the Ship, differences more
or leſſe notable would be obſerved in ſome of the fore-named
fects, and there is no doubt but that the ſmoke would ſtay behind
as much as the Air it ſelf; the flies alſo, and the gnats being
dered by the Air would not be able to follow the motion of the
Ship, if they were ſeparated at any diſtance from it. But keeping
neer thereto, becauſe the Ship it ſelf as being an unfractuous
brick, carrieth along with it part of its neereſt Air, they would
follow the ſaid Ship without any pains or difficulty. And for the
like reaſon we ſee ſometimes in riding poſt, that the troubleſome
flies and ^{*} hornets do follow the horſes flying ſometimes to one,

ſometimes to another part of the body, but in the falling drops
1the difference would be very ſmall; and in the ſalts, and
ons of grave bodies altogether imperceptible.
The anſwer to
the argument
ken from the flight
of birds contrary
to the motion of the
Earth.
An experiment
with which alone
is ſhewn the nullity
of all the
ons produced
gainst the motion
of the Earth.
* Tafaris,
flyes.
SAGR. Though it came not into my thoughts to make triall of
theſe obſervations, when I was at Sea, yet am I confident that they
will ſucceed in the ſame manner, as you have related; in
tion of which I remember that being in my Cabbin I have asked
an hundred times whether the Ship moved or ſtood ſtill; and
ſometimes I have imagined that it moved one way, when it ſteered
quite another way. I am therefore as hitherto ſatisfied and
vinced of the nullity of all thoſe experiments that have been
duced in proof of the negative part. There now remains the
jection founded upon that which experience ſhews us, namely, that
a ſwift Vertigo or whirling about hath a faculty to extrude and
diſperſe the matters adherent to the machine that turns round;
whereupon many were of opinion, and Ptolomy amongſt the reſt,
that if the Earth ſhould turn round with ſo great velocity, the
ſtones and creatures upon it ſhould be toſt into the Skie, and
that there could not be a morter ſtrong enough to faſten buildings
ſo to their foundations, but that they would likewiſe ſuffer a like
extruſion.
SALV. Before I come to anſwer this objection, I cannot but
take notice of that which I have an hundred times obſerved, and
not without laughter, to come into the minds of moſt men ſo ſoon
as ever they hear mention made of this motion of the Earth, which
is believed by them ſo fixt and immoveable, that they not only
ver doubted of that reſt, but have ever ſtrongly believed that all
other men aſwell as they, have held it to be created immoveable,
and ſo to have continued through all ſucceeding ages: and being

ſetled in this perſwaſion, they ſtand amazed to hear that any one
ſhould grant it motion, as if, after that he had held it to be
veable, he had fondly thought it to commence its motion then
(and not till then) when Pythagoras (or whoever elſe was the firſt
hinter of its mobility) ſaid that it did move. Now that ſuch a
liſh conceit (I mean of thinking that thoſe who admit the motion
of the Earth, have firſt thought it to ſtand ſtill from its creation,
untill the time of Pythagoras, and have onely made it moveable
after that Pythagor as eſteemed it ſo) findeth a place in the mindes
of the vulgar, and men of ſhallow capacities, I do not much
der; but that ſuch perſons as Ariſtotle and Ptolomy ſhould alſo
run into this childiſh miſtake, is to my thinking a more admirable
and unpardonable folly.
The ſtupidity of
ſome that think the
Earth to have
gun to move, when
Pythagoras began
to affirme that it
did ſo.
SAGR. You believe then, Salviatus, that Ptolomy thought, that
in his Diſputation he was to maintain the ſtability of the Earth
againſt ſuch perſons, as granting it to have been immoveable,
till the time of Pythagoras, did affirm it to have been but then
1made moveable, when the ſaid Pythagoras aſcribed unto it
tion.
SALV. We can think no other, if we do but conſider the way

he taketh to confute their aſſertion; the confutation of which
conſiſts in the demolition of buildings, and the toſſing of ſtones,
living creatures and men themſelves up into the Air. And
cauſe ſuch overthrows and extruſions cannot be made upon
dings and men, which were not before on the Earth, nor can men
be placed, nor buildings erected upon the Earth, unleſſe when it
ſtandeth ſtill; hence therefore it is cleer, that Ptolomy argueth
gainſt thoſe, who having granted the ſtability of the Earth for
ſome time, that is, ſo long as living creatures, ſtones, and Maſons
were able to abide there, and to build Palaces and Cities, make it
afterwards precipitately moveable to the overthrow and
of Edifices, and living creatures, &c. For if he had undertook to
diſpute againſt ſuch as had aſcribed that revolution to the Earth
from its firſt creation, he would have confuted them by ſaying,
that if the Earth had alwayes moved, there could never have been
placed upon it either men or ſtones; much leſs could buildings
have been erected, or Cities founded, &c.
Ariſtotle and
Ptolomy ſeem to
confute the
ty of the Earth
gainſt thoſe who
thought that it
ving a long time
ſtood still, did
gin to move in the
time of Pythagoras
SIMP. I do not well conceive theſe Ariſtotelick and
maick inconveniences.
SALV. Ptolomey either argueth againſt thoſe who have
ed the Earth always moveable; or againſt ſuch as have held that
it ſtood for ſome time ſtill, and hath ſince been ſet on moving.
If againſt the firſt, he ought to ſay, that the Earth did not always
move, for that then there would never have been men, animals, or
edifices on the Earth, its vertigo not permitting them to ſtay
thereon. But in that he arguing, ſaith that the Earth doth not
move, becauſe that beaſts, men, and houſes before plac'd on the
Earth would precipitate, he ſuppoſeth the Earth to have been once
in ſuch a ſtate, as that it did admit men and beaſts to ſtay, and
build thereon; the which draweth on the conſequence, that it
did for ſome time ſtand ſtill, to wit, was apt for the abode of
nimals and erection of buildings. Do you now conceive what I
would ſay?
SIMP. I do, and I do not: but this little importeth to the
merit of the cauſe; nor can a ſmall miſtake of Ptolomey,
mitted through inadvertencie be ſufficient to move the Earth,
when it is immoveable. But omitting cavils, let us come to the
ſubſtance of the argument, which to me ſeems unanſwerable.
SALV. And I, Simplicius, will drive it home, and re-inforce it,
by ſhewing yet more ſenſibly, that it is true that grave bodies
turn'd with velocity about a ſettled centre, do acquire an impetus
of moving, and receding to a diſtance from that centre, even
1then when they are in a ſtate of having a propenſion of moving
naturally to the ſame. Tie a bottle that hath water in it, to
the end of a cord, and holding the other end faſt in your hand,
and making the cord and your arm the ſemi-diameter, and the
knitting of the ſhoulder the centre, ſwing the bottle very faſt
bout, ſo as that it may deſcribe the circumference of a circle,
which, whether it be parallel to the Horizon, or perpendicular to
it, or any way inclined, it ſhall in all caſes follow, that the
ter will not fall out of the bottle: nay, he that ſhall ſwing it,
ſhall find the cord always draw, and ſtrive to go farther from the
ſhoulder. And if you bore a hole in the bottom of the bottle,
you ſhall ſee the water ſpout forth no leſs upwards into the skie,
than laterally, and downwards to the Earth; and if inſtead of
ter, you ſhall put little pebble ſtones into the bottle, and ſwing it
in the ſame manner, you ſhall find that they will ſtrive in the like
manner againſt the cord. And laſtly, we ſee boys throw ſtones
a great way, by ſwinging round a piece of a ſtick, at the end of
which the ſtone is let into a ſlit (which ſtick is called by them a
ſling;) all which are arguments of the truth of the concluſion,
to wit, that the vertigo or ſwing conferreth upon the moveable,
a motion towards the circumference, in caſe the motion be ſwift:
and therefore if the Earth revolve about its own centre, the
tion of the ſuperficies, and eſpecially towards the great circle,
as being incomparably more ſwift than thoſe before named, ought
to extrude all things up into the air.
SIMP. The Argument ſeemeth to me very well proved and
inforced; and I believe it would be an hard matter to anſwer and
overthrow it.
SALV. Its ſolution dependeth upon certain notions no leſs
known and believed by you, than by my ſelf: but becauſe they
come not into your mind, therefore it is that you perceive not the
anſwer; wherefore, without telling you it (for that you know the
ſame already) I ſhall with onely aſſiſting your memory, make you
to refute this argument.
SIMP. I have often thought of your way of arguing, which
hath made me almoſt think that you lean to that opinion of Pla-

to, Quòd noſtrum ſcire ſit quoddam reminiſci; therefore I intreat
you to free me from this doubt, by letting me know your
ment.
Our krowledg is
a kind of
cence according to
Plato.
SALV. What I think of the opinion of Plato, you may gather
from my words and actions. I have already in the precedent
ferences expreſly declared my ſelf more than once; I will purſue
the ſame ſtyle in the preſent caſe, which may hereafter ſerve you
for an example, thereby the more eaſily to gather what my
nion is touching the attainment of knowledg, when a time ſhall
1offer upon ſome other day: but I would not have Sagredus
fended at this digreſſion.
SAGR. I am rather very much pleaſed with it, for that I
member that when I ſtudied Logick, I could never comprehend that
ſo much cry'd up and moſt potent demonſtration of Ariſtotle.
SALV. Let us go on therefore; and let Simplicius, tell me
what that motion is which the ſtone maketh that is held faſt in the
ſlit of the ſling, when the boy ſwings it about to throw it a great
way?
SIMP. The motion of the ſtone, ſo long as it is in the ſlit, is
circular, that is, moveth by the arch of a circle, whoſe ſtedfaſt
centre is the knitting of the ſhoulder, and its ſemi-diameter the arm
and ſtick.
SALV. And when the ſtone leaveth the ſling, what is its
tion? Doth it continue to follow its former circle, or doth it go
by another line?
SIMP. It will continue no longer to ſwing round, for then it
would not go farther from the arm of the projicient, whereas
we ſee it go a great way off.
SALV. With what motion doth it move then?
SIMP. Give me a little time to think thereof; For I have
ver conſidered it before.
SALV. Hark hither, Sagredus; this is the Quoddam reminiſci
in a ſubject well underſtood. You have pauſed a great while,
Simplicius.
SIMP. As far as I can ſee, the motion received in going out of
the ſling, can be no other than by a right line; nay, it muſt
ceſſarily be ſo, if we ſpeak of the pure adventitious impetus. I
was a little puzled to ſee it make an arch, but becauſe that arch
bended all the way upwards, and no other way, I conceive that

that incurvation cometh from the gravity of the ſtone, which
turally draweth it downwards. The impreſſed impetus, I ſay,
without reſpecting the natural, is by a right line.
The motion
preſſed by the
jicient is onely by a
right line.
SALV. But by what right line? Becauſe infinite, and towards
every ſide may be produced from the ſlit of the ſling, and from the
point of the ſtones ſeparation from the ſling.
SIMP. It moveth by that line which goeth directly from the
motion which the ſtone made in the ſling.
SALV. The motion of the ſtone whilſt it was in the ſlit, you
have affirmed already to be circular; now circularity oppoſeth
directneſs, there not being in the circular line any part that is
rect or ſtreight.
SIMP I mean not that the projected motion is direct in
ſpect of the whole circle, but in reference to that ultimate point,
where the circular motion determineth. I know what I would
1ſay, but do not well know how to expreſs my ſelf.
SALV. And I alſo perceive that you underſtand the buſineſs,
but that you have not the proper terms, wherewith to expreſs the
ſame. Now theſe I can eaſily teach you; teach you, that is, as
to the words, but not as to the truths, which are things. And that
you may plainly ſee that you know the thing I ask you, and onely
want language to expreſs it, tell me, when you ſhoot a bullet out
of a gun, towards what part is it, that its acquired impetus
eth it?
SIMP. Its acquired impetus carrieth it in a right line, which
continueth the rectitude of the barrel, that is, which inclineth
ther to the right hand nor to the left, nor upwards not
wards.
SALV. Which in ſhort is aſmuch as to ſay, it maketh no angle
with the line of ſtreight motion made by the ſling.
SIMP. So I would have ſaid.
SALV. If then the line of the projects motion be to continue
without making an angle upon the circular line deſcribed by it,
whilſt it was with the projicient; and if from this circular motion it
ought to paſs to the right motion, what ought this right line to be?
SIMP. It muſt needs be that which toucheth the circle in the
point of ſeparation, for that all others, in my opinion, being
longed would interſect the circumference, and by that means make
ſome angle therewith.
SALV. You have argued very well, and ſhewn your ſelf half a
Geometrician. Keep in mind therefore, that your true opinion
is expreſt in theſe words, namely, That the project acquireth an
impetus of moving by the Tangent, the arch deſcribed by the
motion of the projicient, in the point of the ſaid projects
tion from the projicient.
SIMP. I underſtand you very well, and this is that which I
would ſay.
SALV. Of a right line which toucheth a circle, which of its
points is the neareſt to the centre of that circle?
SIMP. That of the contact without doubt: for that is in the
circumference of a circle, and the reſt without: and the points of
the circumference are all equidiſtant from the centre.
SALV. Therefore a moveable departing from the contact, and
moving by the ſtreight Tangent, goeth continually farther and
farther from the contact, and alſo from the centre of the circle.
SIMP. It doth ſo doubtleſs.
SALV. Now if you have kept in mind the propoſitions, which
you have told me, lay them together, and tell me what you gather
from them.
SIMP. I think I am not ſo forgetful, but that I do remember
1
them. From the things premiſed I gather that the project ſwiftly
ſwinged round by the projicient, in its ſeparating from it, doth
tain an impetus of continuing its motion by the right line, which
toucheth the circle deſcribed by the motion of the projicient in
the point of ſeparation, by which motion the project goeth
tinually receding from the centre of the circle deſcribed by the
motion of the projicient.
The project
veth by the
gent of the circle of
the motion
dent in the point of
ſeparation.
SALV. You know then by this time the reaſon why grave
dies ſticking to the rim of a wheele, ſwiftly moved, are extruded
and thrown beyond the circumference to yet a farther diſtance
from the centre.
SIMP. I think I underſtand this very well; but this new
ledg rather increaſeth than leſſeneth my incredulity that the Earth
can turn round with ſo great velocity, without extruding up into
the sky, ſtones, animals, &c.
SALV. In the ſame manner that you have underſtood all this,
you ſhall, nay you do underſtand the reſt: and with recollecting
your ſelf, you may remember the ſame without the help of
thers: but that we may loſe no time, I will help your memory
therein. You do already know of your ſelf, that the circular
tion of the projicient impreſſeth on the project an impetus of
ving (when they come to ſeparate) by the right Tangent, the
circle of the motion in the point of ſeparation, and continuing
long by the ſame the motion ever goeth receding farther and
ther from the projicient: and you have ſaid, that the project
would continue to move along by that right line, if there were not
by its proper weight an inclination of deſcent added unto it; from
which the incurvation of the line of motion is derived. It ſeems
moreover that you knew of your ſelf, that this incurvation
ways bended towards the centre of the Earth, for thither do all
grave bodies tend. Now I proceed a little farther, and ask you,
ther the moveable after its ſeparation, in continuing the right
tion goeth always equally receding from the centre, or if you will,
from the circumference of that circle, of which the precedent
tion was a part; which is as much as to ſay, Whether a moveable,
that forſaking the point of a Tangent, and moving along by the
ſaid Tangent, doth equally recede from the point of contact, and
from the circumference of the circle?
SIMP. No, Sir: for the Tangent near to the point of contact,
recedeth very little from the circumference, wherewith it keepeth
a very narrow angle, but in its going farther and farther
off, the diſtance always encreaſeth with a greater proportion; ſo
that in a circle that ſhould have v. g. ten yards of diameter, a point
of the Tangent that was diſtant from the contact but two palms,
would be three or four times as far diſtant from the circumference
1of the circle, as a point that was diſtant from the contaction one
palm, and the point that was diſtant half a palm, I likewiſe believe
would ſcarſe recede the fourth part of the diſtance of the ſecond:
fo that within an inch or two of the contact, the ſeparation of the
Tangent from the circumference is ſcarſe diſcernable.
SALV. So that the receſſion of the project from the
rence of the precedent circular motion is very ſmall in the
ing?
SIMP. Almoſt inſenſible.
SALV. Now tell me a little; the project, which from the
tion of the projicient receiveth an impetus of moving along the
Tangent in a right line, and that would keep unto the ſame, did
not its own weight depreſs it downwards, how long is it after the
ſeparation, ere it begin to decline downwards.
SIMP. I believe that it beginneth preſently; for it not
ving any thing to uphold it, its proper gravity cannot but

A grave project,
as ſoon as it is
parated from the
projicient begineth
to decline.
SALV. So that, if that ſame ſtone, which being extruded from
that wheel turn'd about very faſt, had as great a natural
ſion of moving towards the centre of the ſaid wheel, as it hath to
move towards the centre of the Earth, it would be an eaſie
ter for it to return unto the wheel, or rather not to depart from it;
in regard that upon the begining of the ſeparation, the receſſion
ing ſo ſinall, by reaſon of the infinite acuteneſs of the angle of
contact, every very little of inclination that draweth it back
wards the centie of the wheel, would be ſufficient to retain it
on the rim or circumference.
SIMP. I queſtion not, but that if one ſuppoſe that which
ther is, nor can be, to wit, that the inclination of thoſe grave
dies was to go towards the centre of the wheel, they would never
come to be extruded or ſhaken off.
SALV. But I neither do, nor need to ſuppoſe that which is not;
for I will not deny but that the ſtones are extruded. Yet I ſpeak
this by way of ſuppoſition, to the end that you might grant me
the reſt. Now fancy to your ſelf, that the Earth is that great
wheel, which moved with ſo great velocity is to extrude the ſtones.
You could tell me very well even now, that the motion of
ction ought to be by that right line which toucheth the Earth in
the point of ſeparation: and this Tangent, how doth it notably
recede from the ſuperficies of the Terreſtrial Globe?
SIMP. I believe, that in a thouſand yards, it will not recede
from the Earth an inch.
SALV. And did you not ſay, that the project being drawn by
its own weight, declineth from the Tangent towards the centre of
the Earth?
1
SIMP. I ſaid ſo, and alſo confeſſe the reſt: and do now plainly
underſtand that the ſtone will not ſeparate from the Earth, for
that its receſſion in the beginning would be ſuch, and ſo ſmall,
that it is a thouſand times exceeded by the inclination which the
ſtone hath to move towards the centre of the Earth, which
tre in this caſe is alſo the centre of the wheel. And indeed it muſt
be confeſſed that the ſtones, the living creatures, and the other
grave bodies cannot be extruded; but here again the lighter things
beget in me a new doubt, they having but a very weak propenſion
of deſcent towards the centre; ſo that there being wanting in
them that faculty of withdrawing from the ſuperficies, I ſee not,
but that they may be extruded; and you know the rule, that ad
deſtruendum ſufficit unum.
SAVL. We will alſo give you ſatisfaction in this. Tell me
therefore in the firſt place, what you underſtand by light matters,
that is, whether you thereby mean things really ſo light, as that
they go upwards, or elſe not abſolutely light, but of ſo ſmall
vity, that though they deſcend downwards, it is but very ſlowly;
for if you mean the abſolutely light, I will be readier than your
ſelf to admit their extruſion.
SIMP. I ſpeak of the other ſort, ſuch as are feathers, wool,
ton, and the like; to lift up which every ſmall force ſufficeth:
yet nevertheleſſe we ſee they reſt on the Earth very quietly.
SALV. This pen, as it hath a natural propenſion to deſcend
wards the ſuperficies of the Earth, though it be very ſmall, yet I
muſt tell you that it ſufficeth to keep it from mounting upwards:
and this again is not unknown to you your ſelf; therefore tell me
if the pen were extruded by the Vertigo of the Earth, by what
line would it move?
SIMP. By the tangent in the point of ſeparation.
SALV. And when it ſhould be to return, and re-unite it ſelf to
the Earth, by what line would it then move?
SIMP. By that which goeth from it to the centre of the
Earth.
SALV. So then here falls under our conſideration two
ons; one the motion of projection, which beginneth from the
point of contact, and proceedeth along the tangent; and the
ther the motion of inclination downwards, which beginneth from
the project it ſelf, and goeth by the ſecant towards the centre; and
if you deſire that the projection follow, it is neceſſary that the
petus by the tangent overcome the inclination by the ſecant: is it
not ſo?
SIMP. So it ſeemeth to me.
SALV. But what is it that you think neceſſary in the motion
of the projicient, to make that it may prevail over that
1tion, from which enſueth the ſeparation and elongation of the
pen from the Earth?
SIMP. I cannot tell.
SALV. How, do you not know that? The moveable is here
the ſame, that is, the ſame pen; now how can the ſame moveable
ſuperate and exceed it ſelf in motion?
SIMP. I do not ſee how it can overcome or yield to it ſelf in
motion, unleſſe by moving one while faſter, and another while
ſlower.
SALV. You ſee then, that you do know it. If therefore the
projection of the pen ought to follow, and its motion by the
gent be to overcome its motion by the ſecant, what is it requiſite
that their velocities ſhould be?
SIMP. It is requiſite that the motion by the tangent be greater
than that other by the ſecant. But wretch that I am! Is it not
only many thouſand times greater than the deſcending motion of
the pen, but than that of the ſtone? And yet like a ſimple fellow
I had ſuffered my ſelf to be perſwaded, that ſtones could not be
extruded by the revolution of the Earth. I do therefore revoke
my former ſentence, and ſay, that if the Earth ſhould move,
ſtones, Elephants, Towers, and whole Cities would of neceſſity be
toſt up into the Air; and becauſe that that doth not evene, I
clude that the Earth doth not move.
SALV. Softly Simplicius, you go on ſo faſt, that I begin to be
more afraid for you, than for the pen. Reſt a little, and obſerve what
I am going to ſpeap. If for the reteining of the ſtone or pen
nexed to the Earths ſurface it were neceſſary that its motion of
deſcent were greater, or as much as the motion made by the
gent; you would have had reaſon to ſay, that it ought of neceſſity
to move as faſt, or faſter by the ſecant downwards, than by the
tangent Eaſtwards: But did not you tell me even now, that a
thouſand yards of diſtance by the tangent from the contact, do
remove hardly an inch from the circumference? It is not
ent therefore that the motion by the tangent, which is the ſame
with that of the diurnall Vertigo, (or haſty revolution) be fimply
more ſwift than the motion by the ſecant, which is the ſame with
that of the pen in deſcending; but it is requiſite that the ſame be
ſo much more ſwift as that the time which ſufficeth for the pen
to move v.g. a thouſand yards by the tangent, be inſufficient for
it to move one ſole inch by the ſecant. The which I tell you ſhall
never be, though you ſhould make that motion never ſo ſwift,
and this never ſo ſlow.
SIMP. And why might not that by the tangent be ſo ſwift, as
not to give the pen time to return to the ſurface of the Earth?
SALV. Try whether you can ſtate the caſe in proper termes,
1and I will give you an anſwer. Tell me therefore, how much do
you think ſufficeth to make that motion ſwifter than this?
SIMP. I will ſay for example, that if that motion by the
gent were a million of times ſwifter than this by the ſecant, the
pen, yea, and the ſtone alſo would come to be extruded.
SALV. You ſay ſo, and ſay that which is falſe, onely for
want, not of Logick, Phyſicks, or Metaphyſicks, but of
try; for if you did but underſtand its firſt elements, you would
know, that from the centre of a circle a right line may be drawn
to meet the tangent, which interſecteth it in ſuch a manner, that
the part of the tangent between the contact and the ſecant, may
be one, two, or three millions of times greater than that part of
the ſecant which lieth between the tangent and the circumference,
and that the neerer and neerer the ſecant ſhall be to the contact,
this proportion ſhall grow greater and greater in infinitum; ſo
that it need not be feared, though the vertigo be ſwift, and the
motion downwards ſlow, that the pen or other lighter matter can
begin to riſe upwards, for that the inclination downwards always
exceedeth the velocity of the projection.
SAGR. I do not perfectly apprehend this buſineſſe.
SALV. I will give you a moſt univerſal yet very eaſie demon­

ſtration thereof. Let a proportion be given between B A [in Fig.
3.] and C: And let B A be greater than C at pleaſure. And let
there be deſcribed a circle, whoſe centre is D. From which it is
required to draw a ſecant, in ſuch manner, that the tangent may
be in proportion to the ſaid ſecant, as B A to C. Let A I be
ſuppoſed a third proportional to B A and C. And as B I is to
I A, ſo let the diameter F E be to E G; and from the point G,
let there be drawn the tangent G H. I ſay that all this is done as
was required; and as B A is to C, ſo is H G to G E. And in
gard that as B I is to I A, ſo is F E to E G; therefore by
ſition, as B A is to A I; ſo ſhall F G be to G E. And becauſe C
is the middle proportion between B A and A I; and G H is a
middle term between F G and G E; therefore, as B A is to C,
ſo ſhall F G be to G H; that is H G to G E, which was to be
demonſtrated.
A geometrical
demonſtration to
prove the
bility of extruſion
by means of the
terreſtrial vertigo.
SAGR. I apprehend this demonſtration; yet nevertheleſſe, I
am not left wholly without hæſitation; for I find certain
ſed ſcruples role to and again in my mind, which like thick and
dark clouds, permit me not to diſcern the cleerneſſe and neceſſity
of the concluſion with that perſpicuity, which is uſual in
matical Demonſtrations. And that which I ſtick at is this. It is
true that the ſpaces between the tangent and the circumference do
gradually diminiſh in infinitum towards the contact; but it is alſo
true on the contrary, that the propenſion of the moveable to
1deſcending groweth leſs & leſs in it, the nearer it is to the firſt term
of its deſcent; that is, to the ſtate of reſt; as is manifeſt from that
which you declare unto us, demonſtrating that the deſcending grave
body departing from reſt, ought to paſſe thorow all the degrees of
tardity comprehended between the ſaid reſt, & any aſſigned degree
of velocity, the which grow leſs and leſs in infinitum. To which may
be added, that the ſaid velocity and propenſion to motion, doth for
another reaſon diminiſh to infinity; and it is becauſe the gravity of
the ſaid moveable may infinitely diminiſh. So that the cauſes which
diminiſh the propenſion of aſcending, and conſequently favour
the projection, are two; that is, the levity of the moveable, and its
vicinity to the ſtate of reſt; both which are augmentable in infinit.
and theſe two on the contrary being to contract but with one ſole
cauſe of making the projection, I cannot conceive how it alone,
though it alſo do admit of infinite augmentation, ſhould be able to
remain invincible againſt the union & confederacy of the others, w^{ch}
are two, and are in like manner capable of infinite augmentation.
SALV. This is a doubt worthy of Sagredus; and to explain it ſo as
that we may more cleerly apprehend it, for that you ſay that you
your ſelf have but a confuſed Idea of it, we will diſtinguiſh of the
ſame by reducing it into figure; which may alſo perhaps afford us
ſome caſe in reſolving the ſame. Let us therefore [in Fig. 4.] draw
a perpendicular line towards the centre, and let it be AC, and to it
at right angles let there be drawn the Horizontal line A B, upon
which the motion of the projection ought to be made; now the
ject would continue to move along the ſame with an even motion, if
ſo be its gravity did not incline it downwards. Let us ſuppoſe from
the point A a right line to be drawn, that may make any angle at
pleaſure with the line A B; which let be A E, and upon AB let us
mark ſome equal ſpaces AF, FH, HK, and from them let us let fall
the perpendiculars FG, HI, K L, as far as AE. And becauſe, as al
ready hath been ſaid, the deſcending grave body departing from reſt,
goeth from time to time acquiring a greater degree of velocity,
according as the ſaid time doth ſucceſſively encreaſe; we may
ceive the ſpaces AF, FH, HK, to repreſent unto us equal times; and
the perpendiculars FG, HI, KL, degrees of velocity acquired in the
ſaid times; ſo that the degree of velocity acquired in the whole time
A K, is as the line K L, in reſpect to the degree H I, acquired in the
time AH, and the degree FG in the time AF; the which degrees KL,
HI, FG, are (as is manifeſt) the ſame in proportion, as the times K A,
HA, F A, and if other perpendiculars were drawn from the points
marked at pleaſure in the line F A, one might ſucceſſively find
grees leſſe and leſſe in infinitum, proceeding towards the point A,
repreſenting the firſt inſtant of time, and the firſt ſtate of reſt. And
this retreat towards A, repreſenteth the firſt propenſion to the
1motion of deſcent, diminiſhed in infinitum by the approach of
the moveable to the firſt ſtate of reſt, which approximation is
augmentable in infinitum. Now let us find the other diminution
of velocity, which likewiſe may proceed to infinity, by the
minution of the gravity of the moveable, and this ſhall be
ſented by drawing other lines from the point A, which contein
angles leſſe than the angle B A E, which would be this line A D,
the which interſecting the parallels K L, H I, F G, in the points
M, N, and O, repreſent unto us the degrees F O, H N, K M,
acquired in the times A F, A H, A K, leſſe than the other
grees F G, H I, K L, acquired in the ſame times; but theſe
latter by a moveable more ponderous, and thoſe other by a
moveable more light. And it is manifeſt, that by the retreat of
the line E A towards A B, contracting the angle E A B (the
which may be done in infinitum, like as the gravity may in
nitum be diminiſhed) the velocity of the cadent moveable may
in like manner be diminiſhed in infinitum, and ſo conſequently
the cauſe that impeded the projection; and therefore my thinks
that the union of theſe two reaſons againſt the projection,
niſhed to infinity, cannot be any impediment to the ſaid
ction. And couching the whole argument in its ſhorteſt terms, we
will ſay, that by contracting the angle E A B, the degrees of
locity L K, I H, G F, are diminiſhed; and moreover by the
treat of the parallels K L, H I, F G, towards the angle A, the
fame degrees are again diminiſhed; and both theſe diminutions
extend to infinity: Therefore the velocity of the motion of
ſcent may very well diminiſh ſo much, (it admitting of a twoſold
diminution in infinitum) as that it may not ſuffice to reſtore the
moveable to the circumference of the wheel, and thereupon may
occaſion the projection to be hindered and wholly obviated.
Again on the contrary, to impede the projection, it is
ſary that the ſpaces by which the project is to deſcend for the
reuniting it ſelf to the Wheel, be made ſo ſhort and cloſe
ther, that though the deſcent of the moveable be retarded, yea
more, diminiſhed in infinitum, yet it ſufficeth to reconduct it thither:
and therefore it would be requiſite, that you find out a
on of the ſaid ſpaces, not only produced to infinity, but to ſuch an
infinity, as that it may ſuperate the double infinity that is made in
the diminution of the velocity of the deſcending moveable. But
how can a magnitude be diminiſhed more than another, which
hath a twofold diminution in infinitum? Now let Simplicius
ſerve how hard it is to philoſophate well in nature, without
metry. The degrees of velocity diminiſhed in infinitum, as well
by the diminution of the gravity of the moveable, as by the
proxination to the firſt term of the motion, that is, to the ſtate
1of reſt, are alwayes determinate, and anſwer in proportion to the
parallels comprehended between two right lines that concur in
an angle, like to the angle B A E, or B A D, or any other
infinitely more acute, alwayes provided it be
But the diminution of the ſpaces thorow which the moveable is
to be conducted along the circumference of the wheel, is
tionate to another kind of diminution, comprehended between
lines that contain an angle infinitely more narrow and acute, than
any rectilineal angle, how acute ſoever, which is that in our
ſent caſe. Let any point be taken in the perpendicular A C, and
making it the centre, deſcribe at the diſtance C A, an arch A M P,
the which ſhall interſect the parallels that determine the degrees of
velocity, though they be very minute, and comprehended within
a moſt acute rectilineal angle; of which parallels the parts that
lie between the arch and the tangent A B, are the quantities of
the ſpaces, and of the returns upon the wheel, alwayes leſſer (and
with greater proportion leſſer, by how much neerer they approach
to the contact) than the ſaid parallels of which they are parts.
The parallels comprehended between the right lines in retiring
wards the angle diminiſh alwayes at the ſame rate, as v.g. A H
ing divided in two equal parts in F, the parallel H I ſhall be
ble to F G, and ſub-dividing F A, in two equal parts, the
lel produced from the point of the diviſion ſhall be the half of
F G; and continuing the ſub-diviſion in infinitum, the ſubſequent
parallels ſhall be alwayes half of the next preceding; but it doth
not ſo fall out in the lines intercepted between the tangent and
the circumference of the circle: For if the ſame ſub-diviſion be
made in F A; and ſuppoſing for example, that the parallel which
cometh from the point H, were double unto that which commeth
from F, this ſhall be more then double to the next following, and
continually the neerer we come towards the contact A, we ſhall
find the precedent lines contein the next following three, four,
ten, an hundred, a thouſand, an hundred thouſand, an hundred
millions of times, and more in infinitum. The brevity therefore of
ſuch lines is ſo reduced, that it far exceeds what is requiſite to make
the project, though never ſo light, return, nay more, continue
unremoveable upon the circumference.
SAGR. I very well comprehend the whole diſcourſe, and upon
what it layeth all its ſtreſſe, yet nevertheleſſe methinks that he
that would take pains to purſue it, might yet ſtart ſome further
queſtions, by ſaying, that of thoſe two cauſes which render the
deſcent of the moveable ſlower and ſlower in infinitum, it is
feſt, that that which dependeth on the vicinity to the firſt term of
the deſcent, increaſeth alwayes in the ſame proportion, like as the
parallels alwayes retain the ſame proportion to each other, &c.
1but that the diminution of the ſame velocity, dependent on the
diminution of the gravity of the moveable (which vvas the ſecond
cauſe) doth alſo obſerve the ſame proportion, doth not ſo plainly
appear, And vvho ſhall aſſure us that it doth not proceed
ding to the proportion of the lines intercepted between the ſecant,
and the circumference; or vvhether vvith a greater proportion?
SALV. I have aſſumed for a truth, that the velocities of
bles deſcending naturally, vvill follovv the proportion of their
vities, with the favour of Simplicius, and of Ariſtotle, who doth
in many places affirm the ſame, as a propoſition manifeſt: You,
in favour of my adverſary, bring the ſame into queſtion, and ſay
that its poſſible that the velocity increaſeth with greater
tion, yea and greater in infinitum than that of the gravity; ſo that
all that hath been ſaid falleth to the ground: For maintaining
whereof, I ſay, that the proportion of the velocities is much leſſe
than that of the gravities; and thereby I do not onely ſupport
but confirme the premiſes. And for proof of this I appeal unto
experience, which will ſhew us, that a grave body, howbeit thirty
or fourty times bigger then another; as for example, a ball of
lead, and another of ſugar, will not move much more than twice
as faſt. Now if the projection would not be made, albeit the
locity of the cadent body ſhould diminiſh according to the
portion of the gravity, much leſſe would it be made ſo long as the
velocity is but little diminiſhed, by abating much from the
ty. But yet ſuppoſing that the velocity diminiſheth with a
tion much greater than that wherewith the gravity decreaſeth, nay
though it were the ſelf-ſame wherewith thoſe parallels conteined
between the tangent and circumference do decreaſe, yet cannot I
ſee any neceſſity why I ſhould grant the projection of matters of
never ſo great levity; yea I farther averre, that there could no ſuch
projection follow, meaning alwayes of matters not properly and
abſolutely light, that is, void of all gravity, and that of their own
natures move upwards, but that deſcend very ſlowly, and
have very ſmall gravity. And that which moveth me ſo to think
is, that the diminution of gravity, made according to the
tion of the parallels between the tangent and the circumference,
hath for its ultimate and higheſt term the nullity of weight, as thoſe
parallels have for their laſt term of their diminution the contact it
ſelf, which is an indiviſible point: Now gravity never diminiſheth
ſo far as to its laſt term, for then the moveable would ceaſe to be
grave; but yet the ſpace of the reverſion of the project to the
circumference is reduced to the ultimate minuity, which is when
the moveable reſteth upon the circumference in the very point of
contact; ſo as that to return thither it hath no need of ſpace:
and therefore let the propenſion to the motion of deſcent be
1ver ſo ſmall, yet is it alwayes more than ſufficient to reconduct the
moveable to the circumference, from which it is diſtant but its leaſt
ſpace, that is, nothing at all.
SAGR. Your diſcourſe, I muſt confeſs, is very accurate; and
yet no leſs concluding than it is ingenuous; and it muſt be
ted that to go about to handle natural queſtions, without
try, is to attempt an impoſſibility.
SALV. But Simplicius will not ſay ſo; and yet I do not think
that he is one of thoſe Peripateticks that diſſwade their Diſciples
from ſtudying the Mathematicks, as Sciences that vitiate the
ſon, and render it leſſe apt for contemplation.
SIMP. I would not do ſo much wrong to Plato, but yet I may
truly ſay with Aristotle, that he too much loſt himſelf in, and too
much doted upon that his Geometry: for that in concluſion theſe
Mathematical ſubtilties Salviatus are true in abſtract, but applied
to ſenſible and Phyſical matter, they hold not good. For the
Mathematicians will very well demonſtrate for example, that
Sphæratangit planum in puncto; a poſition like to that in diſpute,
but when one cometh to the matter, things ſucceed quite another
way. And ſo I may ſay of theſe angles of contact, and theſe
proportions; which all evaporate into Air, when they are applied
to things material and ſenſible.
SALV. You do not think then, that the tangent toucheth the
ſuperficies of the terreſtrial Globe in one point only?
SIMP. No, not in one ſole point; but I believe that a right
line goeth many tens and hundreds of yards touching the ſurface
not onely of the Earth, but of the water, before it ſeparate from
the ſame.
SALV. But if I grant you this, do not you perceive that it
keth ſo much the more againſt your cauſe? For if it be ſuppoſed
that the tangent was ſeparated from the terreſtrial ſuperficies, yet
it hath been however demonſtrated that by reaſon of the great
cuity of the angle of contingence (if happily it may be call'd an
angle) the project would not ſeparate from the ſame; how much
leſſe cauſe of ſeparation would it have, if that angle ſhould be
wholly cloſed, and the ſuperficies and the tangent become all one?

Perceive you not that the Projection would do the ſame thing
on the ſurface of the Earth, which is aſmuch as to ſay, it would
do juſt nothing at all? You ſee then the power of truth, which
while you ſtrive to oppoſe it, your own aſſaults themſelves uphold
and defend it. But in regard that you have retracted this errour,
I would be loth to leave you in that other which you hold, namely,
that a material Sphere doth not touch a plain in one ſole point:
and I could wiſh ſome few hours converſation with ſome perſons
converſant in Geometry, might make you a little more intelligent
1amongſt thoſe who know nothing thereof. Now to ſhew you how
great their errour is who ſay, that a Sphere v.g. of braſſe, doth not
touch a plain v.g. of ſteel in one ſole point, Tell me what
ceipt you would entertain of one that ſhould conſtantly aver, that
the Sphere is not truly a Sphere.
The truth
ſometimes gaines
ſtrength by
tradiction.
SIMP. I would eſteem him wholly devoid of reaſon.
SALV. He is in the ſame caſe who ſaith that the material Sphere

doth not touch a plain, alſo material, in one onely point; for to
ſay this is the ſame, as to affirm that the Sphere is not a Sphere.
And that this is true, tell me in what it is that you conſtitute the
Sphere to conſiſt, that is, what it is that maketh the Sphere differ
from all other ſolid bodies.
The sphere
though material,
toucheth the
rial plane but in
one point onely.
SIMP. I believe that the eſſence of a Sphere conſiſteth in

ving all the right lines produced from its centre to the
rence, equal.
The definition of
the ſphere.
SALV. So that, if thoſe lines ſhould not be equal, there ſame
ſolidity would be no longer a ſphere?
SIMP. True.
SALV. Go to; tell me whether you believe that amongſt the
many lines that may be drawn between two points, that may be
more than one right line onely.
SIMP. There can be but one.
SALV. But yet you underſtand that this onely right line ſhall
again of neceſſity be the ſhorteſt of them all?
SIMP. I know it, and alſo have a demonſtration thereof,
duced by a great Peripatetick Philoſopher, and as I take it, if my
memory do not deceive me, he alledgeth it by way of reprehending
Archimedes, that ſuppoſeth it as known, when it may be
ſtrated.
SALV. This muſt needs be a great Mathematician, that knew
how to demonſtrate that which Archimedes neither did, nor could
demonſtrate. And if you remember his demonſtration, I would
gladly hear it: for I remember very well, that Archimedes in his
Books, de Sphærà & Cylindro, placeth this Propoſition amongſt the
Poſtulata; and I verily believe that he thought it demonſtrated.
SIMP. I think I ſhall remember it, for it is very eaſie and
ſhort.
SALV. The diſgrace of Archimedes, and the honour of this
loſopher ſhall be ſo much the greater.
SIMP. I will deſcribe the Figure of it. Between the points

A and B, [in Fig. 5.] draw the right line A B, and the curve line
A C B, of which we will prove the right to be the ſhorter: and
the proof is this; take a point in the curve-line, which let be C,
and draw two other lines, A C and C B, which two lines together;
are longer than the ſole line A B, for ſo demonſtrateth Euelid.
1But the curve-line A C B, is greater than the two right-lines A C,
and C B; therefore, à fortiori, the curve-line A C B, is much
greater than the right line A B, which was to be
The
tion of a
tick, to prove the
right line to be the
ſhorteſt of all lines.
The Paralogiſm
of the ſame
tetick, which
veth ignotum per
ignotius.
SALV. I do not think that if one ſhould ranſack all the
logiſms of the world, there could be found one more commodious
than this, to give an example of the moſt ſolemn fallacy of all
fallacies, namely, than that which proveth ignotum per ignotius.
SIMP. How ſo?
SALV. Do you ask me how ſo? The unknown concluſion
which you deſire to prove, is it not, that the curved line A C B, is
longer than the right line A B; the middle term which is taken
for known, is that the curve-line A C B, is greater than the two
lines A C and C B, the which are known to be greater than A B;
And if it be unknown whether the curve-line be greater than the
ſingle right-line A B, ſhall it not be much more unknown whether
it be greater than the two right lines A C & C B, which are known
to be greater than the ſole line A B, & yet you aſſume it as known?
SIMP. I do not yet very well perceive wherein lyeth the
lacy.
SALV. As the two right lines are greater than A B, (as may be
known by Euclid) and in as much as the curve line is longer than
the two right lines A C and B C, ſhall it not not be much greater
than the ſole right line A B?
SIMP. It ſhall ſo.
SALV. That the curve-line A C B, is greater than the right
line A B, is the concluſion more known than the middle term,
which is, that the ſame curve-line is greater than the two
lines A C and C B. Now when the middle term is leſs known
than the concluſion, it is called a proving ignotum per ignotius.
But to return to our purpoſe, it is ſufficient that you know the
right line to be the ſhorteſt of all the lines that can be drawn
tween two points. And as to the principal concluſion, you ſay,
that the material ſphere doth not touch the ſphere in one ſole
point. What then is its contact?
SIMP. It ſhall be a part of its ſuperficies.
SALV. And the contact likewiſe of another ſphere equal to the
firſt, ſhall be alſo a like particle of its ſuperficies?
SIMP. There is no reaſon vvhy it ſhould be othervviſe.
SALV. Then the tvvo ſpheres vvhich touch each other, ſhall
touch vvith the tvvo ſame particles of a ſuperficies, for each of them
agreeing to one and the ſame plane, they muſt of neceſſity agree
in like manner to each other. Imagine now that the two ſpheres

[in Fig. 6.] whoſe centres are A and B, do touch one another:
and let their centres be conjoyned by the right line A B, which
paſſeth through the contact. It paſſeth thorow the point C, and
1another point in the contact being taken as D, conjoyn the two
right lines A D and B D, ſo as that they make the triangle A D B;
of which the two ſides A D and D B ſhall be equal to the other one
A C B, both thoſe and this containing two ſemidiameters, which
by the definition of the ſphere are all equal: and thus the right
line A B, drawn between the two centres A and B, ſhall not be the
ſhorteſt of all, the two lines A D and D B being equal to it: which
by your own conceſſion is abſurd.
A demon ſtration
that the ſphere
cheth the plane but
in one point.
SIMP. This demonſtration holdeth in the abſtracted, but not in
the material ſpheres.
SALV. Inſtance then wherein the fallacy of my argument
ſiſteth, if as you ſay it is not concluding in the material ſpheres, but
holdeth good in the immaterial and
Why the ſphere in
abſtract, toucheth
the plane onely in
one point, and not
the material in
conerete.
SIMP. The material ſpheres are ſubject to many accidents,
which the immaterial are free from. And becauſe it cannot be,
that a ſphere of metal paſſing along a plane, its own weight ſhould
not ſo depreſs it, as that the plain ſhould yield ſomewhat, or that
the ſphere it ſelf ſhould not in the contact admit of ſome
on. Moreover, it is very hard for that plane to be perfect, if for
nothing elſe, yet at leaſt for that its matter is porous: and
haps it will be no leſs difficult to find a ſphere ſo perfect, as that
it hath all the lines from the centre to the ſuperficies, exactly
equal.
SALV. I very readily grant you all this that you have ſaid; but
it is very much beſide our purpoſe: for whilſt you go about to
ſhew me that a material ſphere toucheth not a material plane in
one point alone, you make uſe of a ſphere that is not a ſphere, and
of a plane that is not a plane; for that, according to what you
ſay, either theſe things cannot be found in the world, or if they
may be found, they are ſpoiled in applying them to work the effect.
It had been therefore a leſs evil, for you to have granted the
cluſion, but conditionally, to wit, that if there could be made of
matter a ſphere and a plane that were and could continue perfect,
they would touch in one ſole point, and then to have denied that
any ſuch could be made.
SIMP. I believe that the propoſition of Philoſophers is to be
underſtood in this ſenſe; for it is not to be doubted, but that the
imperfection of the matter, maketh the matters taken in
crete, to diſagree with thoſe taken in abſtract.
SALV. What, do they not agree? Why, that which you your
ſelf ſay at this inſtant, proveth that they punctually agree.
SIMP. How can that be?
SALV. Do you not ſay, that through the imperfection of the
matter, that body which ought to be perfectly ſpherical, and that
plane which ought to be perfectly level, do not prove to be the
1ſame in concrete, as they are imagined to be in abſtract?
SIMP. This I do affirm.
SALV. Then when ever in concrete you do apply a material Sphere

to a material plane, youapply an imperfect Sphere to an imperfect
plane, & theſe you ſay do not touch only in one point. But I muſt
tell you, that even in abſtract an immaterial Sphere, that is, not a
perfect Sphere, may touch an immaterial plane, that is, not a
fect plane, not in one point, but with part of its ſuperficies, ſo that
hitherto that which falleth out in concrete, doth in like manner
hold true in abſtract. And it would be a new thing that the
putations and rates made in abſtract numbers, ſhould not
wards anſwer to the Coines of Gold and Silver, and to the
chandizes in concrete. But do you know Simplicius, how this
commeth to paſſe? Like as to make that the computations agree
with the Sugars, the Silks, the Wools, it is neceſſary that the
accomptant reckon his tares of cheſts, bags, and ſuch other things:
So when the Geometricall Philoſopher would obſerve in concrete
the effects demonſtrated in abſtract, he muſt defalke the
ments of the matter, and if he know how to do that, I do aſſure
you, the things ſhall jump no leſſe exactly, than Arithmstical
computations. The errours therefore lyeth neither in abſtract, nor
in concrete, nor in Geometry, nor in Phyſicks, but in the
tor, that knoweth not how to adjuſt his accompts. Therefore if
you had a perfect Sphere and plane, though they were material,
you need not doubt but that they would touch onely in one point.
And if ſuch a Sphere was and is impoſſible to be procured, it was
much beſides the purpoſe to ſay, Quod Sphæra ænea non tangit in
puncto. Furthermore, if I grant you Simplicius, that in matter a
figure cannot be procured that is perfectly ſpherical, or perfectly
level: Do you think there may be had two materiall bodies,
whoſe ſuperficies in ſome part, and in ſome ſort are incurvated as
irregularly as can be deſired?
Things are
actly the ſame in
abſtract as in
crete.
SIMP. Of theſe I believe that there is no want.
SALV. If ſuch there be, then they alſo will touch in one ſole

point; for this contact in but one point alone is not the ſole and
peculiar priviledge of the perfect Sphere and perfect plane. Nay, he
that ſhould proſecute this point with more ſubtil contemplations
would finde that it is much harder to procure two bodies that

touch with part of their ſnperſicies, than with one point onely.
For if two ſuperficies be required to combine well together, it is
neceſſary either, that they be both exactly plane, or that if one be
convex, the other be concave; but in ſuch a manner concave,
that the concavity do exactly anſwer to the convexity of the other:
the which conditions are much harder to be found, in regard of
their too narrow determination, than thoſe others, which in their
caſuall latitude are infinite.
1
Contact in a
gle point is not
culiar to the
fect Spheres onely?
but belongeth to all
curved figures.
It is more
cult to find Figures
that touch with a
part of their
face, than in one
ſole point.
SIMP. You believe then, that two ſtones, or two pieces of
ron taken at chance, and put together, do for the moſt part touch
in one ſole point?
SALV. In caſual encounters, I do not think they do; as well
becauſe for the moſt part there will be ſome ſmall yielding filth
upon them, as becauſe that no diligence is uſed in applying them
without ſtriking one another; and every ſmall matter ſufficeth to
make the one ſuperficies yield ſomewhat to the other; ſo that
they interchangeably, at leaſt in ſome ſmall particle, receive ſigure
from the impreſſion of each other. But in caſe their ſuperficies
were very terſe and polite, and that they were both laid upon a
table, that ſo one might not preſſe upon the other, and gently put
towards one another, I queſtion not, but that they might be
brought to the ſimple contact in one onely point.
SAGR. It is requiſite, with your permiſſion, that I propound a
certain ſcruple of mine, which came into my minde, whil'ſt I heard
propoſed by Simplicius, the impoſſibility of finding a materiall
and ſolid body, that is, perfectly of a Spherical figure, and whil'ſt
J law Salviatus in a certain manner, not gainſaying, to give his
conſent thereto; therefore I would know, whether there would
be the ſame difficulty in forming a ſolid of ſome other figure, that
is, to expreſſe my ſelf better, whether there is more difficulty in
reducing a piece of Marble into the figure of a perfect Sphere, than
into a perfect Pyramid, or into a perfect Horſe, or into a perfect
Graſſe-hopper?
SALV. To this I will make you the firſt anſwer: and in the
firſt place, I will acquit my ſelf of the aſſent which you think I
gave to Simplicius, which was only for a time; for I had it alſo in
my thoughts, betore I intended to enter upon any other matter, to
ſpeak that, which, it may be, is the ſame, or very like to that which
you are about to ſay, And anſwering to your firſt queſtion, I ſay,

that if any figure can be given to a Solid, the Spherical is the
eſt of all others, as it is likewiſe the moſt ſimple, and holdeth the
ſame place amongſt ſolid figures, as the Circle holdeth amongſt

the ſuperficial. The deſcription of which Circle, as being more
ſie than all the reſt, hath alone been judged by Mathematicians
worthy to be put amongſt the ^{*} poſtulata belonging to the

ption of all other figures. And the formation of the Sphere is
ſo very eaſie, that if in a plain plate of hard metal you take an
empty or hollow circle, within which any Solid goeth caſually
volving that was before but groſly rounded, it ſhall, without any
other artifice be reduced to a Spherical figure, as perfect as is
ſible for it to be; provided, that that ſame Solid be not leſſe than
the Sphere that would paſſe thorow that Circle. And that which is
yet more worthy of our conſideration is, that within the ſelf-ſame
1incavity one may form Spheres of ſeveral magnitudes. But what

is required to the making of an Horſe, or (as you ſay) of a
hopper, I leave to you to judge, who know that there are but few
ſtatuaries in the world able to undertake ſuch a piece of work.
And I think that herein Simplicius will not diſſent from me.
The Sphericall
Figure is eaſier to
be made than any
other.
The circular
gure only is placed
amongst the
lata of
ticians.
* Demands or
Petitions.
Sphericall
gures of ſundry
magnitudes may
be made with one
onely inſtrument.
SIMP. I know not whether I do at all diffent from you; my
opinion is this, that none of the afore-named figures can be
fectly obteined; but for the approaching as neer as is poſſible to
the moſt perfect degree, I believe that it is incomparably more
ſie to reduce the Solid into a Spherical figure, than into the ſhape
of an Horſe, or Graſſe-hopper?
SAGR. And this greater difficulty, wherein think you doth it
depend?
SIMP. Like as the great facility in forming the Sphere ariſeth

from its abſolute ſimplicity and uniformity ſo the great
larity rendereth the conſtruction of all other figures difficult.
Irregular forms
difficult to be
troduced.
SAGR. Therefore the irregularity being the cauſe of the
culty, than the figure of a ſtone broken with an hammer by
chance, ſhall be one of the figures that are difficult to be
ced, it being perhaps more irregular than that of the horſe?
SIMP. So it ſhould be.
SAGR. But tell me; that figure what ever it is which the ſtone
hath, hath it the ſame in perfection, or no?
SIMP. What it hath, it hath ſo perfectly, that nothing can be
more exact.
SAGR. Then, if of figures that are irregular, and
ly hard to be procured, there are yet infinite which are moſt
fectly obteined, with what reaſon can it be ſaid, that the moſt
ſimple, and conſequently the moſt eaſie of all, is impoſſible to be
procured?
SALV. Gentlemen, with your favour, I may ſay that we have
ſallied out into a diſpute not much more worth than the wool of a
goat; and whereas our argumentations ſhould continually be
verſant about ſerious and weighty points, we conſume our time in

frivolous and impertinent wranglings. Let us call to minde, I pray
you, that the ſearch of the worlds conſtitution, is one of the
teſt and nobleſt Problems that are in nature; and ſo much the
greater, inaſmuch as it is directed to the reſolving of that other;
to wit, of the cauſe of the Seas ebbing and flowing, enquired
to by all the famous men, that have hitherto been in the world,
and poſſibly found out by none of them. Therefore if we have
nothing more remaining for the full confutation of the argument
taken from the Earths vertigo, which was the laſt, alledged to
prove its immobility upon its own centre, let us paſſe to the
amination of thoſe things that are alledged for, and againſt the
Annual Motion.
1
The conſtitution
of the Univerſe is
one of the moſt
ble Problems.
SAGR. I would not have you, Salviatus, meaſure our wits by
the ſcale of yours: you, who uſe to be continually buſied about
the ſublimeſt contemplations, eſteem thoſe notions frivolous and
below you, which we think matters worthy of our profoundeſt
thoughts: yet ſometimes for our ſatisfaction do not diſdain to
ſtoop ſo low as to give way a little to our curioſity. As to the
refutation of the laſt argument, taken from the extruſions of the
diurnal vertigo, far leſs than what hath been ſaid, would have
given me ſatisfaction: and yet the things ſuperfluouſly ſpoken,
ſeemed to me ſo ingenious, that they have been ſo far from
rying my fancy, as that they have, by reaſon of their novelty,
tertained me all along with ſo great delight, that I know not how
to deſire greater: Therefore, if you have any other ſpeculation
to add, produce it, for I, as to my own particular, ſhall gladly
hearken to it.
SALV. I have always taken great delight in thoſe things which
I have had the fortune to diſcover, and next to that, which is my
chief content, I find great pleaſure in imparting them to ſome
friends, that apprehendeth and ſeemeth to like them: Now, in
gard you are one of theſe, ſlacking a little the reins of my
tion, which is much pleaſed when I ſhew my ſelf more
cacious, than ſome other that hath the reputation of a ſharp
ſight, I will for a full and true meaſure of the paſt diſpute,
duce another fallacy of the Sectators of Ptolomey and Ariſtotle,
which I take from the argument alledged.
SAGR. See how greedily I wait to hear it.
SALV. We have hitherto over-paſſed, and granted to Ptolomey,
as an effect indubitable, that the extruſion of the ſtone
ing from the velocity of the wheel turn'd round upon its centre,
the cauſe of the ſaid extruſion encreaſeth in proportion, as the
locity of the vertigo (or whirling) is augmented: from whence
it was inferred, that the velocity of the Earth's vertigo being
very much greater than that of any machin whatſoever, that we
can make to turn round artificially; the extruſion of ſtones, of
animals, &c. would conſequently be far more violent. Now, I
obſerve that there is a great fallacy in this diſcourſe, in that we do
compare theſe velocities indifferently and abſolutely to one
ther. It's true, that if I compare the velocities of the ſame wheel,
or of two wheels equal to each other, that which ſhall be more
ſwiftly turn'd round, ſhall extrude the ſtone with greater
lence; and the velocity encreaſing, the cauſe of the projection
ſhall likewiſe encreaſe: but when the velocity is augmented, not
by encreaſing the velocity in the ſame wheel, which would be by
cauſing it to make a greater number of revolutions in equal times;
but by encreaſing the diameter, and making the wheel greater, ſo
as that the converſion taking up the ſame time in the leſſer wheel,
1as in the greater, the velocity is greater onely in the bigger wheel,

for that its circumference is bigger; there is no man that thinketh
that the cauſe of the extruſion in the great wheel will encreaſe
cording to the proportion of the velocity of its circumference, to
the velocity of the circumference of the other leſſer wheel; for that
this is moſt falſe, as by a moſt expeditious experiment I ſhall thus
groſly declare: We may ſling a ſtone with a ſtick of a yard long,
farther than we can do with a ſtick ſix yards long, though
the motion of the end of the long ſtick, that is of the ſtone placed
in the ſlit thereof, were more than double as ſwift as the
tion of the end of the other ſhorter ſtick, as it would be if
the velocities were ſuch that the leſſer ſtick ſhould turn thrice
round in the time whilſt the greater is making one onely
verſion.
The cauſe of the
projection
eth not according
to the proportion of
the velocity,
creaſed by making
the wheel bigger.
SAGR. This which you tell me, Salviatus, muſt, I ſee, needs
ſucceed in this very manner; but I do not ſo readily apprehend
the cauſe why equal velocities ſhould not operate equally in
extruding projects, but that of the leſſer wheel much more than
the other of the greater wheel; therefore I intreat you to tell me
how this cometh to paſs.
SIMP. Herein, Sagredus, you ſeem to differ much from your
ſelf, for that you were wont to penetrate all things in an inſtant,
and now you have overlook'd a fallacy couched in the experiment
of the ſtick, which I my ſelf have been able to diſcover: and this
is the different manner of operating, in making the projection one
while with the ſhort ſling and another while with the long one,
for if you will have the ſtone fly out of the ſlit, you need not
tinue its motion uniformly, but at ſuch time as it is at the ſwifteſt,
you are to ſtay your arm, and ſtop the velocity of the ſtick;
upon the ſtone which was in its ſwifteſt motion, flyeth out, and
moveth with impetuoſity: but now that ſtop cannot be made in
the great ſtick, which by reaſon of its length and flexibility, doth
not entirely obey the check of the arm, but continueth to
pany the ſtone for ſome ſpace, and holdeth it in with ſo much leſs
force, and not as if you had with a ſtiff ſling ſent it going with a
jerk: for if both the ſticks or ſlings ſhould be check'd by one and
the ſame obſtacle, I do believe they would fly aſwell out of the
one, as out of the other, howbeit their motions were equally
ſwift.
SAGR. With the permiſſion of Salviatus, I will anſwer
thing to Simplicius, in regard he hath addreſſed himſelf to me;
and I ſay, that in his diſcourſe there is ſomewhat good
and ſomewhat bad: good, becauſe it is almoſt all true;
bad, becauſe it doth not agree with our caſe: Truth is, that when
that which carrieth the ſtones with velocity, ſhall meet with a
1check that is immoveable, they ſhall fly out with great
ſity: the ſame effect following in that caſe, which we ſee dayly
to fall out in a boat that running a ſwift courſe, runs a-ground, or
meets with ſome ſudden ſtop, for all thoſe in the boat, being

prized, ſtumble forwards, and fall towards the part whither the
boat ſteered. And in caſe the Earth ſhould meet with ſuch a
check, as ſhould be able to reſiſt and arreſt its vertigo, then indeed
I do believe that not onely beaſts, buildings and cities, but
tains, lakes and ſeas would overturn, and the globe it ſelf would
go near to ſhake in pieces; but nothing of all this concerns our
preſent purpoſe, for we ſpeak of what may follow to the motion
of the Earth, it being turn'd round uniformly, and quietly about
its own centre, howbeit with a great velocity. That likewiſe
which you ſay of the ſlings, is true in part; but was not alledged
by Salviatus, as a thing that punctually agreed with the matter
whereof we treat, but onely, as an example, for ſo in groſs it may
prompt us in the more accurate conſideration of that point,
ther, the velocity increaſing at any rate, the cauſe of the
ction doth increaſe at the ſame rate: ſo that v. g. if a wheel of
ten yards diameter, moving in ſuch a manner that a point of its
circumference will paſs an hundred yards in a minute of an hour,
and ſo hath an impetus able to extrude a ſtone, that ſame impetus
ſhall be increaſed an hundred thouſand times in a wheel of a million
of yards diameter; the which Salviatus denieth, and I incline to his
opinion; but not knowing the reaſon thereof, I have requeſted it
of him, and ſtand impatiently expecting it.
Graming the
urnal vertigo of
the Earth, & that
by ſome ſudden ſtop
or obſtacle it were
arreſted, houſes,
mountains
ſelves, and perhaps
the whole Globe
would be ſhaken n
pieces.
SALV. I am ready to give you the beſt ſatisfaction, that my
abilities will give leave: And though in my firſt diſcourſe you
thought that I had enquired into things eſtranged from our
poſe, yet nevertheleſſe I believe that in the ſequel of the diſpute,
you will find that they do not prove ſo. Therefore let Sagredus
tell me wherein he hath obſerved that the reſiſtance of any
able to motion doth conſiſt.
SAGR. I ſee not for the preſent that the moveable hath any
internal reſiſtance to motion, unleſſe it be its natural inclination
and propenſion to the contrary motion, as in grave bodies, that
have a propenſion to the motion downwards, the reſiſtance is to
the motion upwards; and I ſaid an internal reſiſtance, becauſe
of this, I think, it is you intend to ſpeak, and not of the external
reſiſtances, which are many and accidental.
SALV. It is that indeed I mean, and your nimbleneſſe of wit
hath been too hard for my craftineſſe, but if I have been too
ſhort in asking the queſtion, I doubt whether Sagredus hath been
full enough in his anſwer to ſatisſie the demand; and whether
there be not in the moveable, beſides the natural inclination to the
1contrary term, another intrinſick and natural quality, which

keth it averſe to motion. Therefore tell me again; do you not
think that the inclination v. g. of grave bodies to move
wards, is equal to the reſiſtance of the ſame to the motion of
jection upwards?
The inclination of
grave bodies to the
motion downwards,
is equal to their
reſiſtance to the
motion upwards.
SAGR. I believe that it is exactly the ſame. And for this reaſon
I ſee that two equal weights being put into a ballance, they do
ſtand ſtill in equilibrium, the gravity of the one reſiſting its
ing raiſed by the gravity wherewith the other preſſing
wards would raiſe it.
SALV. Very well; ſo that if you would have one raiſe up the
other, you muſt encreaſe the weight of that which depreſſeth,
or leſſen the weight of the other. But if the reſiſtance to
ing motion cunſiſt onely in gravity, how cometh it to paſſe, that

in ballances of unequal arms, to wit in the ^{*} Stiliard, a weight
ſometimes of an hundred pounds, with its preſſion downwards,
doth not ſuffice to raiſe up on of four pounds; that ſhall
poiſe with it, nay this of four, deſcending ſhall raiſe up that
of an hundred; for ſuch is the effect of the pendant weight upon
the weight which we would weigh? If the reſiſtance to motion
reſideth onely in the gravity, how can the arm with its weight of
four pounds onely, reſiſt the weight of a ſack of wool, or bale of
ſilk, which ſhall be eight hundred, or a thouſand weight; yea
more, how can it overcome the ſack with its moment, and raiſe
it up? It muſt therefore be confeſt Sagredus, that here it maketh
uſe of ſome other reſiſtance, and other force, beſides that of
ſimple gravity.
* A portable
lance wherewith
market-people
weigh their
modities, giving it
gravity by
ving the weight
farther from the
cock: call'd by the
Latines, Campana
trutina.
SAGR. It muſt needs be ſo; therefore tell me what this
cond virtue ſhould be.
SALV. It is that which was not in the ballance of equal
arms; you ſee then what variety there is in the Stiliard; and
on this doubtleſſe dependeth the cauſe of the new effect.
SAGR. I think that your putting me to it a ſecond time, hath
made me remember ſomething that may be to the purpoſe. In
both theſe beams the buſineſs is done by the weight, and by the
motion; in the ballance, the motions are equal, and therefore the
one weight muſt exceed it in gravity before it can move it; in the
ſtiliard, the leſſer weight will not move the greater, unleſs when
this latter moveth little, as being ſlung at a leſſer diſtance, and the
other much, as hanging at a greater diſtance from the lacquet or
cock. It is neceſſary therefore to conclude, that the leſſer weight
overcometh the reſiſtance of the greater, by moving much, whilſt
the other is moved but little.
SALV. Which is as much as to ſay, that the velocity of the
moveable leſs grave, compenſateth the gravity of the moveable
more grave and leſs
1
The greater
city exactly
penſates thegreater
gravity.
SAGR. But do you think that the velocity doth fully make
good the gravity? that is, that the moment and force of a
able of v. g. four pounds weight, is as great as that of one of an
hundred weight, whenſoever that the firſt hath an hundred degrees
of velocity, and the later but four onely?
SALV. Yes doubtleſs, as I am able by many experiments to
demonſtrate: but for the preſent, let this onely of the ſtiliard
ſuffice: in which you ſee that the light end of the beam is then
able to ſuſtain and equilibrate the great Wool ſack, when its
ſtance from the centre, upon which the ſtiliard reſteth and
eth, ſhall ſo much exceed the leſſer diſtance, by how much the
ſolute gravity of the Wool-ſack exceedeth that of the pendent
weight. And we ſee nothing that can cauſe this inſufficiencie in
the great ſack of Wool, to raiſe with its weight the pendent
weight ſo much leſs grave, ſave the diſparity of the motions which
the one and the other ſhould make, whilſt that the Wool ſack by
deſcending but one inch onely, will raiſe the pendent weight an
hundred inclies: (ſuppoſing that the ſack did weigh an hundred
times as much, and that the diſtance of the ſmall weight from the
centre of the beam were an hundred times greater, than the
ſtance between the ſaid centre and the point of the ſacks
on.) And again, the pendent weight its moving the ſpace of an
hundred inches, in the time that the ſack moveth but one inch
onely, is the ſame as to ſay, that the velocity of the motion of the
little pendent weight, is an hundred times greater than the
city of the motion of the ſack. Now fix it in your belief, as a
true and manifeſt axiom, that the reſiſtance which proceedeth from
the velocity of motion, compenſateth that which dependeth on
the gravity of another moveable: So that conſequently, a
able of one pound, that moveth with an hundred degrees of
locity, doth as much reſiſt all obſtruction, as another moveable
of an hundred weight, whoſe velocity is but one degree onely.
And two equal moveables will equally reſiſt their being moved,
if that they ſhall be moved with equal velocity: but if one be
to be moved more ſwiftly than the other, it ſhall make greater
ſiſtance, according to the greater velocity that ſhall be conferred
on it. Theſe things being premiſed, let us proceed to the
nation of our Problem; and for the better underſtanding of
things, let us make a ſhort Scheme thereof. Let two unequal
wheels be deſcribed about this centre A, [in Fig. 7.] and let the
circumference of the leſſer be B G, and of the greater C E H, and
let the ſemidiameter A B C, be perpendicular to the Horizon; and
by the points B and C, let us draw the right lined Tangents B F
and C D; and in the arches B G and C E, take two equal parts
B G and C E: and let the two wheels be ſuppoſed to be turn'd
1round upon their centres with equal velocities, ſo as that two
veables, which ſuppoſe for example to be two ſtones placed in the
points B and C, come to be carried along the circumferences B G
and C E, with equal velocities; ſo that in the ſame time that the
ſtone B ſhall have run the arch B G, the ſtone C will have paſt the
arch C E. I ſay now, that the whirl or vertigo of the leſſer wheel
is much more potent to make the projection of the ſtone B, than
the vertigo of the bigger wheel to make that of the ſtone C.
Therefore the projection, as we have already declared, being to be
made along the tangent, when the ſtones B and C are to ſeparate
from their wheels, and to begin the motion of projection from the
points B and C, then ſhall they be extruded by the impetus
ceived from the vertigo by (or along) the tangents B F and C D.
The two ſtones therefore have equal impetuoſities of running
long the tangents B F and C D, and would run along the ſame, if
they were not turn'd aſide by ſome other force: is it not ſo
gredus?
SAGR. In my opinion the buſineſſe is as you ſay.
SALV. But what force, think you, ſhould that be which averts
the ſtones from moving by the tangents, along which they are
tainly driven by the impetus of the vertigo.
SAGR. It is either their own gravity, or elſe ſome glutinous
matter that holdeth them faſt and cloſe to the wheels.
SALV. But for the diverting of a moveable from the motion
to which nature inciteth it, is there not required greater or leſſer
force, according as the deviation is intended to be greater or
ſer? that is, according as the ſaid moveable in its deviation hath a
greater or leſſer ſpace to move in the ſame time?
SAGR. Yes certainly: for it was concluded even now, that to
make a moveable to move; the movent vertue muſt be increaſed
in proportion to the velocity wherewith it is to move.
SALV. Now conſider, that for the deviating the ſtone upon
the leſſe wheel from the motion of projection, which it would
make by the tangent B F, and for the holding of it faſt to the
wheel, it is required, that its own gravity draw it back the whole
length of the ſecant F G, or of the perpendicular raiſed from the
point G, to the line B F, whereas in the greater wheel the
on needs to be no more than the ſecant D E, or the
lar let fall from the tangent D G to the point E, leſſe by much
than F G, and alwayes leſſer and leſſer according as the wheel is
made bigger. And foraſmuch as theſe retractions (as I may call
them) are required to be made in equal times, that is, whil'ſt the
wheels paſſe the two equal arches B G and C E, that of the ſtone
B, that is, the retraction F G ought to be more ſwift than the
ther D E; and therefore much greater force will be required for
1holding faſt the ſtone B to its little wheel, than for the holding
the ſtone C to its great one, which is as much as to ſay, that ſuch
a ſmall thing will impede the extruſion in the great wheel, as will
not at all hinder it in the little one. It is manifeſt therefore that
the more the wheel augmenteth, the more the cauſe of the
jection diminiſheth.
SAGR. From this which I now underſtand, by help of your
nute diſſertation, I am induced to think, that I am able to ſatisfie
my judgment in a very few words. For equal impetus being
preſſed on both the ſtones that move along the tangents, by the
equal velocity of the two wheels, we ſee the great circumference,
by means of its ſmall deviation from the tangent, to go ſeconding,
as it were, and in a fair way refraining in the ſtone the appetite, if
I may ſo ſay, of ſeparating from the circumference; ſo that any
ſmall retention, either of its own inclination, or of ſome
tion ſufficeth to hold it faſt to the wheel. Which, again, is not
ble to work the like effect in the little wheel, which but little
ſecuting the direction of the tangent, ſeeketh with too much
gerneſſe to hold faſt the ſtone; and the reſtriction and glutination
not being ſtronger than that which holdeth the other ſtone faſt to

the greater wheel, it ^{*} breaks looſe, and runneth along the
gent. Therefore I do not only finde that all thoſe have erred,
who have believed the cauſe of the projection to increaſe
ding to the augmentation of the vertigo's velocity; but I am
further thinking, that the projection diminiſhing in the inlarging of
the wheel, ſo long as the ſame velocity is reteined in thoſe wheels;
it may poſſibly be true, that he that would make the great wheel
extrude things like the little one, would be forced to increaſe
them as much in velocity, as they increaſe in diameter, which he
might do, by making them to finiſh their converſions in equal
times; and thus we may conclude, that the Earths revolution or
vertigo would be no more able to extrude ſtones, than any little
wheel that goeth ſo ſlowly, as that it maketh but one turn in
ty four hours.
* Strappar la
vezza, is to break
the bridle.
SALV. We will enquire no further into this point for the
ſent: let it ſuffice that we have abundantly (if I deceive not my
ſelf) demonſtrated the invalidity of the argument, which at firſt
ſight ſeemed very concluding, and was ſo held by very famous
men: and I ſhall think my time and words well beſtowed, if I
have but gained ſome belief in the opinion of Simplicius, I will
not ſay or the Earths mobility, but only that the opinion of thoſe
that believe it, is not ſo ridiculous and fond, as the rout of vulgar
Philoſophers eſteem it.
SIMP. The anſwers hitherto produced againſt the arguments
brought againſt this Diurnal Revolution of the Earth taken from
1grave bodies falling from the top of a Tower, and from
ctions made perpendicularly upwards, or according to any
tion ſidewayes towards the Eaſt, Weſt, North, South, &c. have
ſomewhat abated in me the antiquated incredulity I had conceived
againſt that opinion: but other greater doubts run in my mind
at this very inſtant, which I know not in the leaſt how to free my
ſelf of, and haply you your ſelf will not be able to reſolve them;
nay, its poſſible you may not have heard them, for they are very
modern. And theſe are the objections of two Authours, that ex
profeſſo write againſt Copernicus. Some of which are read in a

little Tract of natural concluſions; The reſt are by a great both
Philoſopher and Mathematician, inſerted in a Treatiſe which he
hath written in favour of Aristotle, and his opinion touching the
inalterability of the Heavens, where he proveth, that not onely
the Comets, but alſo the new ſtars, namely, that anno 1572. in
Caſſiopeia, and that anno 1604. in Sagittarius were not above the
Spheres of the Planets, but abſolutely beneath the concave of
the Moon in the Elementary Sphere, and this he demonſtrateth
gainſt Tycho, Kepler, and many other Aftronomical Obſervators,
and beateth them at their own weapon; to wit, the Doctrine of
Parallaxes. If you like thereof, I will give you the reaſons of
both theſe Authours, for I have read them more than once,
with attention; and you may examine their ſtrength, and give
your opinion thereon.
Other objections
of two modern
thors against
pernicus.
SALV. In regard that our principal end is to bring upon the
ſtage, and to conſider what ever hath been ſaid for, or againſt the
two Syſtemes, Ptolomaick, and Copernican, it is not good to omit
any thing that hath been written on this ſubject.
SIMP. I will begin therefore with the objections which I finde
in the Treatiſe of Concluſions, and afterwards proceed to the

reſt. In the firſt place then, he beſtoweth much paines in
lating exactly how many miles an hour a point of the terreſtrial
Globe ſituate under the Equinoctial, goeth, and how many miles
are paſt by other points ſituate in other parallels: and not being
content with finding out ſuch motions in horary times, he findeth
them alſo in a minute of an hour; and not contenting himſelf
with a minute, he findes them alſo in a ſecond minute; yea more,
he goeth on to ſhew plainly, how many miles a Cannon bullet
would go in the ſame time, being placed in the concave of the

nar Orb, ſuppoſing it alſo as big as Copernicus himſelf repreſenteth
it, to take away all ſubterfuges from his adverſary. And having
made this moſt ingenious and exquiſite ſupputation, he ſheweth,
that a grave body falling from thence above would conſume more
than ſix dayes in attaining to the centre of the Earth, to which all
grave bodies naturally move. Now if by the abſolute Divine
1Power, or by ſome Angel, a very great Cannon bullet were
ed up thither, and placed in our Zenith or vertical point, and from
thence let go at liberty, it is in his, and alſo in my opinion, a moſt
incredible thing that it, in deſcending downwards, ſhould all the
way maintain it ſelf in our vertical line, continuing to turn round
with the Earth, about its centre, for ſo many dayes, deſcribing
under the Equinoctial a Spiral line in the plain of the great circle
it ſelf: and under other Parallels, Spiral lines about Cones, and
under the Poles falling by a ſimple right line. He, in the next
place, ſtabliſheth and confirmeth this great improbability by
ving, in the way of interrogations, many difficulties impoſſible to
be removed by the followers of Copernicus; and they are, if I do
well remember-----.
The firſt
ction of the
dern Author of
the little tract of
Concluſions.
A Cannon
let would ſpend
more than ſix days
in falling from the
Concave of the
Moon to the
tre of the Earth,
according to the
pinion of that
dern Author of the
Concluſions.
SALV. Take up a little, good Simplicius, and do not load me
with ſo many novelties at once: I have but a bad memory, and
therefore I muſt not go too faſt. And in regard it cometh into
my minde, that I once undertook to calculate how long time ſuch a
grave body falling from the concave of the Moon, would be in
paſſing to the centre of the Earth, and that I think I remember
that the time would not be ſo long; it would be fit that you ſhew
us by what rule this Author made his calculation.
SIMP. He hath done it by proving his intent à fortiori, a
cient advantage for his adverſaries, ſuppoſing that the velocity of
the body falling along the vertical line, towards the centre of the
Earth, were equal to the velocity of its circular motion, which it
made in the grand circle of the concave of the Lunar Orb.
Which by equation would come to paſſe in an hour, twelve
ſand ſix hundred German miles, a thing which indeed ſavours of
impoſſibility: Yet nevertheleſſe, to ſhew his abundant caution,
and to give all advantages to his adverſaries, he ſuppoſeth it for
true, and concludeth, that the time oſ the fall ought however to
be more than ſix dayes.
SALV. And is this the ſum of his method? And doth he by
this demonſtration prove the time of the fall to be above ſix
dayes?
SAGR. Me thinks that he hath behaved himſelf too modeſtly,
for that having it in the power of his will to give what velocity he
pleaſed to ſuch a deſcending body, and might aſwell have made it
ſix moneths, nay, ſix years in falling to the Earth, he is content
with ſix dayes. But, good Salviatus, ſharpen my appetite a
tle, by telling me in what manner you made your computation, in
regard you ſay, that you have heretofore caſt it up: for I am
fident that if the queſtion had not required ſome ingenuity in
working it, you would never have applied your minde unto
it.
1
SALV. It is not enough, Sagredus, that the ſubjects be noble
and great, but the buſineſſe conſiſts in handling it nobly. And
who knoweth not, that in the diſſection of the members of
a beaſt, there may be diſcovered infinite wonders of provident
and prudent Nature; and yet for one, that the Anatomiſt
ſects, the butcher cuts up a thouſand. Thus I, who am now
ſeeking how to ſatisfie your demand, cannot tell with which of the
two ſhapes I had beſt to appear on the Stage; but yet, taking
heart from the example of Simplicius, his Authour, I will,
out more delays, give you an account (if I have not forgot) how
I proceeded. But before I go any further, I muſt not omit to tell
you, that I much fear that Simplicius hath not faithfully related
the manner how this his Authour found, that the Cannon
let in coming from the concave of the Moon to the centre of the
Earth, would ſpend more than fix dayes: for if he had
ſed that its velocity in deſcending was equal to that of the
concave (as Simplicius ſaith he doth ſuppoſe) he would have
ſhewn himſelf ignorant of the firſt, and more ſimple principles
of Geometry; yea, I admire that Simplicius, in admitting the
ſuppoſition which he ſpeaketh of, doth not ſee the monſtrous
ſurdity that is couched in it.
SIMP. Its poſſible that I may have erred in relating it; but
that I ſee any fallacy in it, I am ſure is not true.
SALV. Perhaps I did not rightly apprehend that which you
ſaid, Do you not ſay, that this Authour maketh the velocity
of the bullet in deſcending equall to that which it had in
ning round, being in the concave of the Moon, and that
ming down with the ſame velocity, it would reach to the centre
in ſix dayes?
SIMP. So, as I think, he writeth.
SALV. And do not you perceive a ſhamefull errour therein?
But queſtionleſſe you diſſemble it: For it cannot be, but that
you ſhould know that the ſemidiameter of the Circle is leſſe than

the ſixth part of the circumference; and that conſequently, the
time in which the moveable ſhall paſſe the ſemidiameter, ſhall be
leſſe than the ſixth part of the time; in which, being moved
with the ſame velocity, it would paſſe the circumference; and
that therefore the bullet deſcending with the velocity,
with it moved in the concave, will arrive in leſſe than four hours
at the centre, ſuppoſing that in the concave one revolution
ſhould be conſummate in twenty four hours, as he muſt of
ceſſity have ſuppoſed it, for to keep it all the way in the ſame
vertical line.
A ſhamefull
errour in the
gument taken from
the bullets falling
out of the Moons
concave.
SIMP. Now I thorowly perceive the miſtake: but yet I
would not lay it upon him undeſervedly, for it's poſſible that I
1may have erred in rehearſing his Argument, and to avoid running
into the ſame miſtakes for the future, I could wiſh I had his
Book; and if you had any body to ſend for it, I would take it
for a great favour.
SAGR. You ſhall not want a Lacquey that will runne for it
with all ſpeed: and he ſhall do it preſently, without loſing any
time; in the mean time Salviatus may pleaſe to oblige us with his
computation.
SIMP. If he go, he ſhall finde it lie open upon my Desk,
together with that of the other Author, who alſo argueth
gainſt Copernicus.
SAGR. We will make him bring that alſo for the more
tainty: and in the interim Salviatus ſhall make his calculation: I
have diſpatch't away a meſſenger.
SALV. Above all things it muſt be conſidered, that the motion
of deſcending grave bodies is not uniform, but departing from

reſt they go continually accelerating: An effect known and
ſerved by all men, unleſſe it be by the forementioned modern
thour, who not ſpeaking of acceleration, maketh it even and
niforme. But this general notion is of no avail, if it be not known
according to what proportion this increaſe of velocity is made; a
concluſion that hath been until our times unknown to all
phers; and was firſt found out & demonſtrated by the ^{*} Academick,

our common friend, who in ſome of his ^{*} writings not yet

ed, but in familiarity ſhewn to me, and ſome others of his
quaintance he proveth, how that the acceleration of the right
tion of grave bodies, is made according to the numbers uneven
beginning ab unitate, that is, any number of equal times being
ſigned, if in the firſt time the moveable departing from reſt ſhall

have paſſed ſuch a certain ſpace, as for example, an ell, in the
cond time it ſhall have paſſed three ells, in the third five, in the
fourth ſeven, and ſo progreſſively, according to the following odd
numbers; which in ſhort is the ſame, as if I ſhould ſay, that the
ſpaces paſſed by the moveable departing from its reſt, are unto

each other in proportion double to the proportion of the times,
in which thoſe ſpaces are meaſured; or we will ſay, that the
ſpaces paſſed are to each other, as the ſquares of their times.
An exact
pute of the time of
the fall of the
non bullet from the
Moons concave to
the Earths centre.
* The Author.
* By theſe
tings, he every
where meanes his
Dialogues, De
tu, which I promiſe
to give you in my
ſecond Volume.
Acceleration of
the natural motion
of grave bodies is
made according to
the odde numbers
beginning at unity.
The ſpaces paſt
by the falling
grave body are as
the ſquares of their
times.
SAGR. This is truly admirable: and do you ſay that there is
a Mathematical demonſtration for it?
SALV. Yes, purely Mathematical; and not onely for this, but
for many other very admirable paſſions, pertaining to natural
tions, and to projects alſo, all invented, and demonſtrated by Our

Friend, and I have ſeen and conſidered them all to my very great
content and admiration, ſeeing a new compleat Doctrine to ſpring
up touching a ſubject, upon which have been written hundreds of
1Volumes; and yet not ſo much as one of the infinite admirable
concluſions that thoſe his writings contain, hath ever been
ſerved, or underſtood by any one, before Our Friend made
them out.
An intire and
new Science of the
Academick
ning local motion.
SAGR. You make me loſe the deſire I had to underſtand
more in our diſputes in hand, onely that I may hear ſome of
thoſe demonſtrations which you ſpeak of; therefore either give
them me preſently, or at leaſt promiſe me upon your word, to
appoint a particular conference concerning them, at which
plicius alſo may be preſent, if he ſhall have a mind to hear the
paſſions and accidents of the primary effect in Nature.
SIMP. I ſhall undoubtedly be much pleaſed therewith, though
indeed, as to what concerneth Natural Philoſophy, I do not think
that it is neceſſary to deſcend unto minute particularities, a
ral knowledg of the definition of motion, and of the
ction of natural and violent, even and accelerate, and the like,
ſufficing: For if this were not ſufficient, I do not think that
ſtotle would have omitted to have taught us what ever more was
neceſſary.
SALV. It may be ſo. But let us not loſe more time about
this, which I promiſe to ſpend half a day apart in, for your
faction; nay, now I remember, I did promiſe you once before to
ſatisfie you herein. Returning therefore to our begun
tion of the time, wherein the grave cadent body would paſs from
the concave of the Moon to the centre of the Earth, that we may
not proceed arbitrarily and at randon, but with a Logical method,
we will firſt attempt to aſcertain our ſelves by experiments often
repeated, in how long time a ball v. g. of Iron deſcendeth to the
Earth from an altitude of an hundred yards.
SAGR. Let us therefore take a ball of ſuch a determinate
weight, and let it be the ſame wherewith we intend to make the
computation of the time of deſcent from the Moon.
SALV. This is not material, for that a ball of one, of ten, of an
hundred, of a thouſand pounds, will all meaſure the ſame hundred
yards in the ſame time.
SIMP. But this I cannot believe, nor much leſs doth Ariſtotle
think ſo, who writeth, that the velocities of deſcending grave
bodies, are in the ſame proportion to one another, as their
vities.
SALV. If you will admit this for true, Simplicius, you muſt

lieve alſo, that two balls of the ſame matter, being let fall in the
ſame moment, one of an hundred pounds, and another of one,
from an altitude of an hundred yards, the great one arriveth at the
ground, before the other is deſcended but one yard onely: Now
bring your fancy, if you can, to imagine, that you ſee the great
1ball got to the ground, when the little one is ſtill within leſs than
a yard of the top of the Tower.
The error of
ſtotle in affirming,
falling grave
dies to move
ding to the
tion of their
ties.
SAGR. That this propoſition is moſt falſe, I make no doubt in
the world; but yet that yours is abſolutely true, I cannot well
aſſure my ſelf: nevertheleſs, I believe it, ſeeing that you ſo
ſolutely affirm it; which I am ſure you would not do, if you had
not certain experience, or ſome clear demonſtration thereof.
SALV. I have both: and when we ſhall handle the buſineſs
of motions apart, I will communicate them: in the interim, that
we may have no more occaſions of interrupting our diſcourſe, we
will ſuppoſe, that we are to make our computation upon a ball of

Iron of an hundred (a) pounds, the which by reiterated
ments deſcendeth from the altitude of an hundred (b) yards, in
five ſecond-minutes of an hour. And becauſe, as we have ſaid,
the ſpaces that are meaſured by the cadent moveable, increaſe in
double proportion; that is, according to the ſquares of the times,
being that the time of one firſt-minute is duodecuple to the time
of five ſeconds, if we multiply the hundred yards by the ſquare of
12, that is by 144, we ſhall have 14400, which ſhall be the
ber of yards that the ſame moveable ſhall paſs in one firſt-minute
of an hour: and following the ſame rule becauſe one hour is 60
minutes, multiplying 14400, the number of yards paſt in one
nute, by the ſquare of 60, that is, by 3600, there ſhall come forth
51840000, the number of yards to be paſſed in an hour, which
make 17280 miles. And deſiring to know the ſpace that the ſaid
ball would paſs in 4 hours, let us multiply 17280 by 16, (which
is the ſquare of 4) and the product will be 276480 miles: which
number is much greater than the diſtance from the Lunar concave
to the centre of the Earth, which is but 196000 miles, making the
diſtance of the concave 56 ſemidiameters of the Earth, as that
dern Author doth; and the ſemidiameter of the Earth 3500 miles,

of 3000 ^{*}Braces to a †mile, which are our Italian miles.
(a) (b) Note that
theſe Calculations
are made in
an weights and
meaſures. And 100
pounds
poiſe make 131 l.
Florentine. And
100 Engliſh yards
makes 150 2/5 Braces
Florent. ſo that the
brace or yard of
our Author is 3/4
of cur yard.
* The Italian
ſure which I
monly tranſl te
yards.
Therefore, Simplicius, that ſpace from the concave of the Moon
to the centre of the Earth, which your Accomptant ſaid could

not be paſſed under more than ſix days, you ſee that (computing
by experience, and not upon the fingers ends) that it ſhall be
ſed in much leſs than four hours; and making the computation
exact, it ſhall be paſſed by the moveable in 3 hours, 22 min. prim.
and 4 ſeconds.
† The Italian mile
is 1000/1056 of our mile.
SAGR. I beſeech you, dear Sir, do not defraud me of this
act calculation, for it muſt needs be very excellent.
SALV. So indeed it is: therefore having (as I have ſaid) by
diligent tryal obſerved, that ſuch a moveable paſſeth in its deſcent,
the height of 100 yards in 5 ſeconds of an hour, we will ſay, if
100 yards are paſſed in 5 ſeconds; in how many ſeconds ſhall
1588000000 yards (for ſo many are in 56 diameters of the Earth)
be paſſed? The rule for this work is, that the third number muſt
be multiplied by the ſquare of the ſecond, of which doth come
14700000000, which ought to be divided by the firſt, that is, by
100, and the root ſquare of the quotient, that is, 12124 is the
number ſought, namely 12124 min. ſecun. of an hour, which are
3 hours, 22 min. prim. and 4 ſeconds.
SAGR. I have ſeen the working, but I know nothing of the
reaſon for ſo working, nor do I now think it a time to ask it.
SALV. Yet I will give it, though you do not ask it, becauſe it
is very eaſie. Let us mark theſe three numbers with the Letters
A firſt, B ſecond, C
8[Figure 8]
third. A and C are the
numbers of the ſpaces,
B is the number of the
time; the fourth number
is ſought, of the time
alſo. And becauſe we
know, that look what
proportion the ſpace A,
hath to the ſpuace C, the
ſame proportion ſhall the
ſquare of the time B
have to the ſqare of the
time, which is ſought.
Therefore by the Golden Rule, let the number C be
plied by the ſquare of the number B, and let the product be
vided by the number A, and the quotient ſhall be the ſquare of
the number ſought, and its ſquare root ſhall be the number it ſelf
that is ſought. Now you ſee how eaſie it is to be underſtood.
SAGR. So are all truths, when once they are found out, but the
difficulty lyeth in finding them. I very well apprehend it, and kindly
thank you. And if there remain any other curioſity touching this
point, I pray you let us hear it; for if I may ſpeak my mind, I
will with the favour of Simplicius, that from your diſcourſes I
wayes learn ſome new motion, but from thoſe of his
phers, I do not remember that I have learn't any thing of
ment.
SALV. There might be much more ſaid touching theſe local
motions; but according to agreement, we will reſerve it to a
ticular conference, and for the preſent I will ſpeak ſomething
touching the Author named by Simplicius, who thinketh he hath
given a great advantage to the adverſe party in granting that, that
Canon bullet in falling from the concave of the Moon may
ſcend with a velocity equal to the velocity wherewith it would
1turn round, ſtaying there above, and moving along with the
urnal converſion. Now I tell him, that that ſame ball falling from
the concave unto the centre, will acquire a degree of velocity
much more than double the velocity of the diurnal motion of the
Lunar concave; and this I will make out by ſolid and not

tinent ſuppoſitions. You muſt know therefore that the grave
body falling and acquiring all the way new velocity according
to the proportion already mentioned, hath in any whatſoever
place of the line of its motion ſuch a degree of velocity, that if it
ſhould continue to move therewith, uniformly without farther
encreaſing it; in another time like to that of its deſcent, it would
paſſe a ſpace double to that paſſed in the line of the precedent
motion of deſcent. And thus for example, if that ball in coming
from the concave of the Moon to its centre hath ſpent three hours,
22 min. prim. and 4 ſeconds, I ſay, that being arrived at the
tre, it ſhall find it ſelf conſtituted in ſuch a degree of velocity, that
if with that, without farther encreaſing it, it ſhould continue to
move uniformly, it would in other 3 hours, 22 min. prim. and
4 ſeconds, paſſe double that ſpace, namely as much as the whole
diameter of the Lunar Orb; and becauſe from the Moons
cave to the centre are 196000 miles, which the ball paſſeth in 3
hours 22 prim. min. and 4 ſeconds, therefore (according to what
hath been ſaid) the ball continuing to move with the velocity
which it is found to have in its arrival at the centre, it would
paſſe in other 3 hours 22 min. prim. and 4 ſeconds, a ſpace
ble to that, namely 392000 miles; but the ſame continuing in
the concave of the Moon, which is in circuit 1232000 miles, and
moving therewith in a diurnal motion, it would make in the ſame
time, that is in 3 hours 22 min. prim. and 4 ſeconds, 172880
miles, which are fewer by many than the half of the 392000
miles. You ſee then that the motion in the concave is not as the
modern Author ſaith, that is, of a velocity impoſſible for the
ing ball to partake of, &c.
The falling
able if it move with
a degree of
ty acquired in a
like time with an
uniform motion, it
ſhall paß a ſpace
double to that
ſed with the
leratedmotion.
SAGR. The diſcourſe would paſs for current, and would give
me full ſatisfaction, if that particular was but ſalved, of the
ving of the moveable by a double ſpace to that paſſed in falling
in another time equal to that of the deſcent, in caſe it doth continue
to move uniformly with the greateſt degree of velocity acquired
in deſcending. A propoſition which you alſo once before
ſed as true, but never demonſtrated.
SALV. This is one of the demonſtrations of Our Friend, and
you ſhall ſee it in due time; but for the preſent, I will with ſome
conjectures (not teach you any thing that is new, but) remember you
of a certain contrary opinion, and ſhew you, that it may haply ſo be.
A bullet of lead hanging in a long and fine thread faſtened to the
1roof, if we remove it far from perpendicularity, and then let it go,
have you not obſerved that, it declining, will paſs freely, and well
near as far to the other ſide of the perpendicular?
SAGR. I have obſerved it very well, and find (eſpecially if the
plummet be of any conſiderable weight) that it riſeth ſo little leſs
than it deſcended, ſo that I have ſometimes thought, that the
ſcending arch is equal to that deſcending, and thereupon made it
a queſtion whether the vibrations might not perpetuate themſelves;
and I believe that they might, if that it were poſſible to remove

the impediment of the Air, which reſiſting penetration, doth ſome
ſmall matter retard and impede the motion of the pendulum,
though indeed that impediment is but ſmall: in favour of which
opinion the great number of vibrations that are made before the
moveable wholly ceaſeth to move, ſeems to plead.
The motion of
grave penduli
might be
ted, impediments
being removed.
SALV. The motion would not be perpetual, Sagredus,
though the impediment of the Air were totally removed, becauſe
there is another much more abſtruſe.
SAGR. And what is that? as for my part I can think of no
other?
SALV. You will be pleaſed when you hear it, but I ſhall not
tell it you till anon: in the mean time, let us proceed. I have
propoſed the obſervation of this Pendulum, to the intent, that you
ſhould underſtand, that the impetus acquired in the deſcending
arch, where the motion is natural, is of it ſelf able to drive the
ſaid ball with a violent motion, as far on the other ſide in the like
aſcending arch; if ſo, I ſay, of it ſelf, all external impediments
being removed: I believe alſo that every one takes it for granted,
that as in the deſcending arch the velocity all the way increaſeth,
till it come to the loweſt point, or its perpendicularity; ſo from
this point, by the other aſcending arch, it all the wav diminiſheth,
untill it come to its extreme and higheſt point: and diminiſhing
with the ſame proportions, where with it did before increaſe, ſo that
the dgrees of the velocities in the points equidiſtant from the point
of perpendicularity, are equal to each other. Hence it ſeemeth
to me (arguing with all due modeſty) that I might eaſily be induced
to believe, that if the Terreſtrial Globe were bored thorow the

centre, a Canon bullet deſcending through that Well, would
quire by that time it came to the centre, ſuch an impulſe of
city, that, it having paſſed beyond the centre, would ſpring it
wards the other way, as great a ſpace, as that was wherewith it had
deſcended, all the way beyond the centre diminiſhing the velocity
with decreaſements like to the increaſements acquired in the
ſcent: and the time ſpent in this ſecond motion of aſcent, I
lieve, would be equal to the time of deſcent. Now if the
able by diminiſhing that its greateſt degree of velocity which it
1had in the centre, ſucceſſively until it come to total extinction,
do carry the moveable in ſuch a time ſuch a certain ſpace, as it had
gone in ſuch a like quantity of time, by the acquiſt of velocity
from the total privation of it until it came to that its greateſt degree;
it ſeemeth very reaſonable, that if it ſhould move always with the
ſaid greateſt degree of velocity it would paſs, in ſuch another
quantity of time, both thoſe ſpaces: For if we do but in our
mind ſucceſſively divide thoſe velocities into riſing and falling
degrees, as v. g. theſe numbers in the margine; ſo that the
firſt ſort unto 10 be ſuppoſed the increaſing velocities, and the
others unto 1, be the decreaſing; and let thoſe of the time
of the deſcent, and the others of the time of the aſcent being
added all together, make as many, as if one of the two ſums of
them had been all of the greateſt degrees, and therefore the
whole ſpace paſſed by all the degrees of the increaſing
ties, and decreaſing, (which put together is the whole
ter) ought to be equal to the ſpace paſſed by the greateſt
cities, that are in number half the aggregate of the increaſing
and decreaſing velocities. I know that I have but obſcurely
expreſſed my ſelf, and I wiſh I may be underſtood.
If the Terreſtrial
Globe were
rated, a grave
dy deſcending by
that bore, would
paß and aſcend as
far beyond the
tre, as it did
ſcend.
SAGR. I think I underſtand you very well; and alſo that I
can in a few words ſhew, that I do underſtand you. You had
a mind to ſay, that the motion begining from reſt, and all the
way increaſing the velocity with equal augmentations, ſuch as
are thoſe of continuate numbers begining at 1, rather at 0,
which repreſenteth the ſtate of reſt, diſpoſed as in the margine:
and continued at pleaſure, ſo as that the leaſt degree may be 0,
and the greateſt v. g. 5, all theſe degrees of velocity wherewith
the moveable is moved, make the ſum of 15; but if the
moveable ſhould move with as many degrees in number as
theſe are, and each of them equal to the biggeſt, which is 5, the
aggregate of all theſe laſt velocities would be double to the
others, namely 30. And therefore the moveable moving with
a like time, but with uniform velocity, which is that of the
higheſt degree 5, ought to paſs a ſpace double to that which it
paſſeth in the accelerate time, which beginneth at the ſtate of reſt.
SALV. According to your quick and piercing way of
hending things, you have explained the whole buſineſs with more
plainneſs than I my ſelf; and put me alſo in mind of adding
thing more: for in the accelerate motion, the augmentation
ing continual, you cannot divide the degrees of velocity, which
continually increaſe, into any determinate number, becauſe
ging every moment, they are evermore infinite. Therefore we
ſhall be the better able to exemplifie our intentions by deſcribing
a Triangle, which let be this A B C, [in Fig. 8.] taking in the
1ſide A C, as many equal parts as we pleaſe, A D, D E, E F, F G,
and drawing by the points D, E, F, G, right lines parallel to the baſe
B C. Now let us imagine the parts marked in the line A C, to be
equal times, and let the parallels drawn by the points D, E, F, G,
repreſent unto us the degrees of velocity accelerated, and
ing equally in equal times; and let the point A be the ſtate of reſt,
from which the moveable departing, hath v. g. in the time A D,
acquired the degree of velocity D H, in the ſecond time we will
ſuppoſe, that it hath increaſed the velocity from D H, as far as to
E I, and ſo ſuppoſing it to have grown greater in the ſucceeding
times, according to the increaſe of the lines F K, G L, &c. but

becauſe the acceleration is made continually from moment to
ment, and not disjunctly from one certain part of time to another;
the point A being put for the loweſt moment of velocity, that is,
for the ſtate of reſt, and A D for the firſt inſtant of time
ing; it is manifeſt, that before the acquiſt of the degree of velocity
D H, made in the time A D, the moveable muſt have paſt by
infinite other leſſer and leſſer degrees gained in the infinite inſtants
that are in the time D A, anſwering the infinite points that are in
the line D A; therefore to repreſent unto us the infinite degrees
of velocity that precede the degree D H, it is neceſſary to imagine
infinite lines ſucceſſively leſſer and leſſer, which are ſuppoſed to
be drawn by the infinite points of the line D A, and parallels to
D H, the which infinite lines repreſent unto us the ſuperficies of
the Triangle A H D, and thus we may imagine any ſpace paſſed
by the moveable, with a motion which begining at reſt, goeth
formly accelerating, to have ſpent and made uſe of infinite degrees
of velocity, increaſing according to the infinite lines that
ing from the point A, are ſuppoſed to be drawn parallel to the
line H D, and to the reſt I E, K F, L G, the motion continuing as
far as one will.
The acceleration
of grave bodies
turally deſcendent,
increaſeth from
moment to moment.
Now let us compleat the whole Parallelogram A M B C, and let
us prolong as far as to the ſide thereof B M, not onely the Parallels
marked in the Triangle, but thoſe infinite others imagined to be
drawn from all the points of the ſide A C; and like as B C, was
the greateſt of thoſe infinite parallels of the Triangle,
ing unto us the greateſt degree of velocity acquired by the
able in the accelerate motion, and the whole ſuperficies of the ſaid
Triangle, was the maſs and ſum of the whole velocity, wherewith
in the time A C it paſſed ſuch a certain ſpace, ſo the parallelogram
is now a maſs and aggregate of a like number of degrees of
locity, but each equal to the greateſt B C, the which maſs of
locities will be double to the maſs of the increaſing velocities in
the Triangle, like as the ſaid Parallelogram is double to the
angle: and therefore if the moveable, that falling did make uſe
1of the accelerated degrees of velocity, anſwering to the triangle
A B C, hath paſſed in ſuch a time ſuch a ſpace, it is very reaſonable
and probable, that making uſe of the uniform velocities anſwering
to the parallelogram, it ſhall paſſe with an even motion in the
ſame time a ſpace double to that paſſed by the accelerate
tion.
SAGR. I am entirely ſatisfied. And if you call this a probable
Diſcourſe, what ſhall the neceſſary demonſtrations be? I wiſh
that in the whole body of common Philoſophy, I could find one
that was but thus
In natural
ences it is not
ceſſary to ſeek
thematicall
dence.
SIMP. It is not neceſſary in natural Philoſophy to ſeek
ſite Mathematical evidence.
SAGR. But this point of motion, is it not a natural queſtion?
and yet I cannot find that Ariſtotle hath demonſtrated any the
leaſt accident of it. But let us no longer divert our intended
Theme, nor do you fail, I pray you Salviatus, to tell me that
which you hinted to me to be the cauſe of the Pendulum's
eſcence, beſides the reſiſtance of the Medium ro penetration.
SALV. Tell me; of two penduli hanging at unequal
ces, doth not that which is faſtned to the longer threed make its
vibrations more ſeldome?
The pendulum
hanging at a
er threed, maketh
its vibrations more
ſeldome than the
pendulum hanging
at a ſhorter threed.
SAGR. Yes, if they be moved to equall diſtances from their
perpendicularity.
SALV. This greater or leſſe elongation importeth nothing at
all, for the ſame pendulum alwayes maketh its reciprocations in
quall times, be they longer or ſhorter, that is, though the pendulum

be little or much removed from its perpendicularity, and if they
are not abſolutely equal, they are inſenſibly different, as
rience may ſhew you: and though they were very unequal, yet
would they not diſcountenance, but favour our cauſe.
fore let us draw the perpendicular A B [in Fig. 9.] and hang from
the point A, upon the threed A C, a plummet C, and another
on the ſame threed alſo, which let be E, and the threed A C, being
removed from its perpendicularity, and then letting go the
mets C and E, they ſhall move by the arches C B D, E G F, and
the plummet E, as hanging at a leſſer diſtance, and withall, as
(by what you ſaid) leſſe removed, will return back again faſter,
and make its vibrations more frequent than the plummet C, and
therefore ſhall hinder the ſaid plummet C, from running ſo much
farther towards the term D, as it would do, if it were free: and
thus the plummet E bringing unto it in every vibration continuall

impediment, it ſhall finally reduce it to quieſcence. Now the
ſame threed, (taking away the middle plummet) is a compoſition
of many grave penduli, that is, each of its parts is ſuch a
lum faſtned neerer and neerer to the point A, and therefore
1ſed to make its vibrations ſucceſſively more and more frequent;
and conſequently is able to bring a continual impediment to the
plummet C; and for a proof that this is ſo, if we do but obſerve
the thread A C, we ſhall ſee it diſtended not directly, but in an
arch; and if inſtead of the thread we take a chain, we ſhall
cern the effect more perſectly; and eſpecially removing the

vity C, to a conſiderable diſtance from the perpendicular A B, for
that the chain being compoſed of many looſe particles, and each of
them of ſome weight, the arches A E C, and A F D, will appear
notably incurvated. By reaſon therefore, that the parts of the
chain, according as they are neerer to the point A, deſire to make
their vibrations more frequent, they permit not the lower parts of
the ſaid chain to ſwing ſo far as naturally they would: and by
continual detracting from the vibrations of the plummet C, they
finally make it ceaſe to move, although the impediment of the air
might be removed.
The vibrations
of the ſame
dulum are made
with the ſame
quency, whether
they be ſmall or
great.
The cauſe which
impedeth the
dulum, and
ceth it to reſt.
The thread or
chain to which a
pendulum is
ned, maketh an
arch, and doth not
ſtretch it ſelfe
ſtreight out in its
vibrations.
SAGR. The books are now come; here take them Simplicius,
and find the place you are in doubt of.
SIMP. See, here it is where he beginneth to argue againſt the
diurnal motion of the Earth, he having firſt confuted the annual.
Motus terræ annuus aſſerrere Copernicanos cogit converſionem
juſdem quotidianam; alias idem terræ Hemiſphærium continenter
ad Solem eſſet converſum obumbrato ſemper averſo. [In Engliſh
thus:] The annual motion of the Earth doth compell the
pernicans to aſſert the daily converſion thereof; otherwiſe the
ſame Hemiſphere of the Earth would be continually turned
wards the Sun, the ſhady ſide being always averſe. And ſo one
half of the Earth would never come to ſee the Sun.
SALV. I find at the very ſirſt ſight, that this man hath not rightly
apprehended the Copernican Hypotheſis, for if he had but taken
notice how he alwayes makes the Axis of the terreſtrial Globe
perpetually parallel to it ſelf, he would not have ſaid, that one
half of the Earth would never ſee the Sun, but that the year
would be one entire natural day, that is, that thorow all parts of
the Earth there would be ſix moneths day, and ſix moneths night,
as it now befalleth to the inhabitants under the Pole, but let
this miſtake be forgiven him, and let us come to what
neth.
SIMP. It followeth, Hanc autem gyrationem Terræ
poſſibilem eſſe ſic demonſtramus. Which ſpeaks in Engliſh thus:
That this gyration of the Earth is impoſſible we thus demonſtrate.
That which enſueth is the declaration of the following figure,
wherein is delineated many deſcending grave bodies, and
ing light bodies, and birds that fly too and again in the air, &c.
SAGR. Let us ſee them, I pray you. Oh! what fine figures,
1what birds, what balls, and what other pretty things are here?
SIMP. Theſe are balls which come from the concave of the
Moon.
SAGR. And what is this?
SIMP. This is a kind of Shell-fiſh, which here at Venice they
call buovoli; and this alſo came from the Moons concave.
SAGR. Indeed, it ſeems then, that the Moon hath a great

er over theſe Oyſter-fiſhes, which we call ^{*} armed ſiſbes.
* Peſci armai, or
armati.
SIMP. And this is that calculation, which I mentioned, of this
Journey in a natural day, in an hour, in a firſt minute, and in a
ſecond, which a point of the Earth would make placed under the
Equinoctial, and alſo in the parallel of 48 gr. And then followeth
this, which I doubted I had committed ſome miſtake in reciting,
therefore let us read it. His poſitis, neceſſe est, terra circulariter
mota, omnia ex aëre eidem, &c. Quod ſi haſce pilas æquales
nemus pondere, magnitudine, gravitate, & in concavo Sphæræ
naris poſitas libero deſcenſui permittamus, ſi motum deorſum
mus celeritate motui circum, (quod tamen ſecus eſt, cum pila A,
&c.) elabentur minimum (ut multum cedamus adverſariis) dies
ſex: quo tempore ſexies circa terram, &c. [In Engliſb thus.]
Theſe things being ſuppoſed, it is neceſſary, the Earth being
cularly moved, that all things from the air to the ſame, &c. So
that if we ſuppoſe theſe balls to be equal in magnitude and
vity, and being placed in the concave of the Lunar Sphere, we
permit them a free deſcent, and if we make the motion
wards equal in velocity to the motion about, (which nevertheleſs
is otherwiſe, if the ball A, &c.) they ſhall be falling at leaſt (that
we may grant much to our adverſaries) ſix dayes; in which time
they ſhall be turned ſix times about the Earth, &c.
SALV. You have but too faithfully cited the argument of this
perſon. From hence you may collect Simplicius, with what
tion they ought to proceed, who would give themſelves up to
lieve others in thoſe things, which perhaps they do not believe
themſelves. For me thinks it a thing impoſſible, but that this
thor was adviſed, that he did deſign to himſelf a circle, whoſe
meter (which amongſt Mathematicians, is leſſe than one third part
of the circumference) is above 72 times bigger than it ſelf: an
errour that affirmeth that to be conſiderably more than 200,
which is leſſe than one.
SAGR. It may be, that theſe Mathematical proportions, which
are true in abſtract, being once applied in concrete to Phyſical and
Elementary circles, do not ſo exactly agree: And yet, I think,
that the Cooper, to find the ſemidiameter of the bottom, which he
is to fit to the Cask, doth make uſe of the rule of Mathematicians
in abſtract, although ſuch bottomes be things meerly material,
1and concrete: therefore let Simplicius plead in excuſe of this
Author; and whether he chinks that the Phyſicks can differ ſo
very much from the Mathematicks.
SIMP. The ſubſtractions are in my opinion inſufficient to ſalve
this difference, which is ſo extreamly too great to be reconciled:
and in this caſe I have no more to ſay but that, Quandoque bonus
dormitet Homerus. But ſuppoſing the calculation of ^{*} Salviatus

to be more exact, and that the time of the deſcent of the ball
were no more than three hours; yet me thinks, that coming from
the concave of the Moon, which is ſo great a diſtance off, it would
be an admirable thing, that it ſhould have an inſtinct of
ing it ſelf all the way over the ſelf-ſame point of the Earth, over
which it did hang in its departure thence and not rather be left a
very great way behind.
* Not
dus, as the Latine
ha hit.
SALV. The effect may be admirable, and not admirable, but
natural and ordinary, according as the things precedent may fall
out. For if the ball (according to the Authors ſuppoſitions)
whilſt it ſtaid in the concave of the Moon, had the circular motion
of twenty four hours together with the Earth, and with the reſt of
the things contained within the ſaid Concave; that very vertue
which made it turn round before its deſcent, will continue it in
the ſame motion in its deſcending. And ſo far it is from not
ing pace with the motion of the Earth, and from ſtaying behind,
that it is more likely to out-go it; being that in its approaches to
the Earth, the motion of gyration is to be made with circles
tinually leſſer and leſſer; ſo that the ball retaining in it ſelf that
ſelf-ſame velocity which it had in the concave, it ought to
pate, as I have ſaid, the vertigo or converſion of the Earth. But
if the ball in the concave did want that circulation, it is not
ged in deſcending to maintain it ſelf perpendicularly over that
point of the Earth, which was juſt under it when the deſcent
gan. Nor will Copernicus, or any of his followers affirm the
ſame.
SIMP. But the Author maketh an objection, as you ſee,
manding on what principle this circular motion of grave and light
bodies, doth depend: that is, whether upon an internal or an
ternal principle.
SALV. Keeping to the Probleme of which we ſpeak, I ſay,
that that very principle which made the ball turn round, whil'ſt it
was in the Lunar concave, is the ſame that maintaineth alſo the
circulation in the deſcent: yet I leave the Author at liberty to
make it internal or external at his pleaſure.
SIMP. The Author proveth, that it can neither be inward nor
outward.
SALV. And I will ſay then, that the ball in the concave did
1not move, and ſo he ſhall not be bound to ſhew how that in
cending it continueth all the way vertically over one point, for
that it will not do any ſuch thing.
SIMP. Very well; But if grave bodies, and light can have no
principle, either internal or external of moving circularly, than
neither can the terreſtrial Globe move with a circular motion: and
thus you have the intent of the Author.
SALV. I did not ſay, that the Earth had no principle, either
interne, or externe to the motion of gyration, but I ſay, that I do
not know which of the two it hath; and yet my not knowing it
hath not a power to deprive it of the ſame; but if this Author
can tell by what principle other mundane bodies are moved round,
of whoſe motion there is no doubt; I ſay, that that which
keth the Earth to move, is a vertue, like to that, by which Mars
and Jupiter are moved, and wherewith he believes that the ſtarry
Sphere it ſelf alſo doth move; and if he will but aſſure me, who is
the mover of one of theſe moveables, I will undertake to be able
to tell him who maketh the Earth to move. Nay more; I will
undertake to do the ſame, if he can but tell me, who moveth the
parts of the Earth downwards.
SIMP. The cauſe of this is moſt manifeſt, and every one knows
that it is gravity.
SALV. You are out, Simplicius, you ſhould ſay, that every
one knowes, that it is called Gravity: but I do not queſtion you
about the name, but the eſſence of the thing, of which eſſence
you know not a tittle more than you know the eſſence of the
mover of the ſtars in gyration; unleſſe it be the name that hath
been put to this, and made familiar, and domeſtical, by the many

experiences which we ſee thereof every hour in the day,: but not
as if we really underſtand any more, what principle or vertue that
is which moveth a ſtone downwards, than we know who moveth
it upwards, when it is ſeparated from the projicient, or who
veth the Moon round, except (as I have ſaid) onely the name,
which more particularly and properly we have aſſigned to the
tion of deſcent, namely, Gravity; whereas for the cauſe of
cular motion, in more general termes, we aſſign the Vertue
ſed, and call the ſame an Intelligence, either aſſiſting, or informing;
and to infinite other motions we aſcribe Nature for their cauſe.
We know no more
who moveth grave
bodies downwards;
than who moveth
the Stars round,
nor know we any
thing of theſe
ſes, more than the
names impoſed on
them by us.
SIMP. It is my opinion, that this Author asketh far leſſe than
that, to which you deny to make anſwer; for he doth not ask
what is nominally and particularly the principle that moveth
grave and light bodies circularly, but whatſoever it be, he
reth to know, whether you think it intrinſecal, or extrinſecal:
For howbeit, v. gr. I do not know, what kind of thing that gravity
is, by which the Earth deſcendeth; yet I know that it is an intern
1principle, ſeeing that if it be not hindered, it moveth
ouſly: and on the contrary, I know that the principle which
veth it upwards, is external, although that I do not know, what
thing that vertue is, impreſſed on it by the projicient.
SALV. Into how many queſtions muſt we excurre, if we would
decide all the difficulties, which ſucceſſively have dependance one
upon another! You call that an external (and you alſo call it a
preternatural and violent) principle, which moveth the grave
ject upwards; but its poſſible that it may be no leſſe interne and
natural, than that which moveth it downwards; it may

ture be called external and violent, ſo long as the moveable is
ned to the projicient; but being ſeparated, what external thing
remaineth for a mover of the arrow, or ball? In ſumme, it muſt
neceſſarliy be granted, that that vertue which carrieth ſuch a
able upwards, is no leſſe interne, than that which moveth it
wards; and I think the motion of grave bodies aſcending by the
impetus conceived, to be altogether as natural, as the motion of
deſcent depending on gravity.
The vertue which
carrieth grave
jects upwards, is
no leſſe natural to
them, than the
gravity which
veth them
wards.
SIMP. I will never grant this; for the motion of deſcent hath
its principle internal, natural, and perpetual, and the motion of
aſcent hath its principle externe, violent, and finite.
SALV. If you refuſe to grant me, that the principles of the
motions of grave bodies downwards and upwards, are equally

ternal and natural; what would you do, if I ſhould ſay, that they
may alſo be the ſame in number?
Contrary
ciples cannot
rally reſide in the
ſame ſubject.
SIMP. I leave it to you to judge.
SALV. But I deſire you your ſelf to be the Judge: Therefore
tell me, Do you believe that in the ſame natural body, there may
reſide interne principles, that are contrary to one another?
SIMP. I do verily believe there cannot.
SALV. What do you think to be the natural inclination of
Earth, of Lead, of Gold, and in ſum, of the moſt ponderous
ters; that is, to what motion do you believe that their interne
principle draweth them?
SIMP. To that towards the centre of things grave, that is, to
the centre of the Univerſe, and of the Earth, whither, if they be
not hindered, it will carry them.
SALV. So that, if the Terreſtrial Globe were bored thorow,
and a Well made that ſhould paſſe through the centre of it, a
Cannon bullet being let fall into the ſame, as being moved by a
natural and intrinſick principle, would paſſe to the centre; and it
would make all this motion ſpontaneouſly, and by intrinſick
ciple, is it not ſo?
SIMP. So I verily believe.
SALV. But when it is arrived at the centre, do you think that
1it will paſſe any further, or elſe that there it would immediately
ſtand ſtill, and move no further?
SIMP. I believe that it would continue to move a great way
further.
SALV. But this motion beyond the centre, would it not be
wards, and according to your aſſertion preternatural, and violent?
And yet on what other principle do you make it to depend, but
only upon the ſelf ſame, which did carry the ball to the centre,
and which you called intrinſecal, and natural? Finde, if you can,
another external projicient, that overtaketh it again to drive it
upwards. And this that hath been ſaid of the motion thorow
the centre, is alſo ſeen by us here above; for the interne impetus

of a grave body falling along a declining ſuperficies, if the ſaid
ſuperficies be reflected the other way, it ſhall carry it, without a
jot interrupting the motion, alſo upwards. A ball of lead that
hangeth by a thread, being removed from its perpendicularity,
ſcendeth ſpontaneouſly, as being drawn by its internal inclination,
and without any interpoſure of reſt, paſſeth beyond the loweſt
point of perpendicularity: and without any additional mover,
moveth upwards. I know that you will not deny, but that the
principle of grave bodies that moveth them downwards, is no leſs
natural, and intrinſecal, than that principle of light bodies, which
moveth them upwards: ſo that I propoſe to your conſideration a
ball of lead, which deſcending through the Air from a great
titude, and ſo moving by an intern principle, and comming to a
depth of water, continueth its deſcent, and without any other
terne mover, ſubmergeth a great way; and yet the motion of
deſcent in the water is preternatural unto it; but yet nevertheleſs
dependeth on a principle that is internal, and not external to the
ball. You ſee it demonſtrated then, that a moveable may be
moved by one and the ſame internal principle, with contrary
tions.
The natural
tion changeth it
ſelfe into that
which is called
ternatural and
olent.
SIMP. I believe there are ſolutions to all theſe objections,
though for the preſent I do not remember them; but however it
be, the Author continueth to demand, on what principle this
cular motion of grave and light bodies dependeth; that is,
ther on a principle internal, or external; and proceeding
wards, ſheweth, that it can be neither on the one, nor on the other,
ſaying; Si ab externo; Deuſne illum excitat per continuum
culum? an verò Angelus, an aër? Et hunc quidem multi
nant. Sed contra----[In Engliſh thus] If from an externe
ciple; Whether God doth not excite it by a continued Miracle?
or an Angel, or the Air? And indeed many do aſſign this. But
on the contrary-----.
SALV. Trouble not your ſelf to read his argument; for I am
1none of thoſe who aſcribe that principle to the ambient air. As
to the Miracle, or an Angel, I ſhould rather incline to this ſide; for
that which taketh beginning from a Divine Miracle, or from an
Angelical operation; as for inſtance, the tranſportation of a
non ball or bullet into the concave of the Moon, doth in all
bability depend on the vertue of the ſame principle for
ing the reſt. But, as to the Air, it ſerveth my turn, that it doth
not hinder the circular motion of the moveables, which we did
ſuppoſe to move thorow it. And to prove that, it ſufficeth (nor is
more required) that it moveth with the ſame motion, and
eth its circulations with the ſame velocity, that the Terreſtrial
Globe doth.
SIMP. And he likewiſe makes his oppoſition to this alſo;
demanding who carrieth the air about, Nature, or Violence?
And proveth, that it cannot be Nature, alledging that that is
trary to truth, experience, and to Copernicus himſelf.
SALV. It is not contrary to Copernicus in the leaſt, who writeth
no ſuch thing; and this Author aſcribes theſe things to him with
two exceſſive courteſie. It's true, he ſaith, and for my part I
think he ſaith well, that the part of the air neer to the Earth,
ing rather a terreſtrial evaporation, may have the ſame nature,
and naturally follow its motion; or, as being contiguous to it,
may follow it in the ſame manner, as the Peripateticks ſay, that
the ſuperiour part of it, and the Element of fire, follow the
tion of the Lunar Concave, ſo that it lyeth upon them to declare,
whether that motion be natural, or violent.
SIMP. The Author will reply, that if Copernicus maketh only
the inferiour part of the Air to move, and ſuppoſeth the upper
part thereof to want the ſaid motion, he cannot give a reaſon, how
that quiet air can be able to carry thoſe grave bodies along with
it, and make them keep pace with the motion of the Earth.
SALV. Copernicus will ſay, that this natural propenſion of the

elementary bodies to ſollow the motion of the Earth, hath a
mited Sphere, out of which ſuch a natural inclination would ceaſe;
beſides that, as I have ſaid, the Air is not that which carrieth the
moveables along with it; which being ſeparated from the Earth,
do follow its motion; ſo that all the objections come to nothing,
which this Author produceth to prove, that the Air cannot cauſe
ſuch effects.
The propenſion
of elementary
dies to follow the
Earth, hath a
mited Sphere of
activity.
SIMP. To ſhew therefore, that that cannot be, it will be
ſary to ſay, that ſuch like effects depend on an interne principle,
againſt which poſition, oboriuntur difficillimæ, immò inextricabiles
quæſtiones ſecundæ, of which ſort are theſe that follow.
pium illud internum vel eſt accidens, vel ſubſtantia. Si primum;
quale nam illud? nam qualitas locomotiva circum, hactenus nulla
1videtur agnita. (In Engliſh thus:) Contrary to which poſition
there do ariſe moſt difficult, yea inextricable ſecond queſtions,
ſuch as theſe; That intern principle is either an accident, or a
ſubſtance. If the firſt; what manner of accident is it? For a
locomotive quality about the centre, ſeemeth to be hitherto
knowledged by none.
SALV. How, is there no ſuch thing acknowledged? Is it not
known to us, that all theſe elementary matters move round,
gether with the Earth? You ſee how this Author ſuppoſeth for
true, that which is in queſtion.
SIMP. He ſaith, that we do not ſee the ſame; and me thinks,
he hath therein reaſon on his ſide.
SALV. We ſee it not, becauſe we turn round together with
them.
SIMP. Hear his other Argument. Quæ etiam ſi eſſet,
modo tamen inveniretur in rebus tam contrariis? in igne, ut in
quâ; in aëre, ut in terra; in viventibus, ut in anima carentibus?
[in Engliſh thus:] Which although it were, yet how could it be
found in things ſo contrary? in the fire, as in the water? in the
air, as in the earth? in living creatures, as in things wanting
life?
SALV. Suppoſing for this time, that water and fire are
ries; as alſo the air and earth; (of which yet much may be ſaid)
the moſt that could follow from thence would be, that thoſe
tions cannot be common to them, that are contrary to one
ther: ſo that v. g. the motion upwards, which naturally agreeth
to fire, cannot agree to water; but that, like as it is by nature
trary to fire: ſo to it that motion ſuiteth, which is contrary to the
motion of fire, which ſhall be the motion deorſùm; but the
cular motion, which is not contrary either to the motion ſurſùm,
or to the motion deorſùm, but may mix with both, as Aristotle
himſelf affirmeth, why may it not equally ſuit with grave bodies
and with light? The motions in the next place, which cannot be
common to things alive, and dead, are thoſe which depend on the
ſoul: but thoſe which belong to the body, in as much as it is
mentary, and conſequently participateth of the qualities of the
lements, why may not they be common as well to the dead corps,
as to the living body? And therefore, if the circular motion be
proper to the elements, it ought to be common to the mixt bodies
alſo.
SAGR. It muſt needs be, that this Author holdeth, that a dead
cat, falling from a window, it is not poſſible that a live cat alſo
could fall; it not being a thing convenient, that a carcaſe ſhould
partake of the qualities which ſuit with things alive.
SALV. Therefore the diſcourſe of this Author concludeth
1nothing againſt one that ſhould affirm, that the principle of the
cular motions of grave and light bodies is an intern accident: I
know not how he may prove, that it cannot be a ſubſtance.
SIMP. He brings many Arguments againſt this. The firſt of
which is in theſe words: Si ſecundum (nempè, ſi dieas tale
pium eſſe ſubſtantiam) illud eſt aut materia, aut forma, aut
ſitum. Sed repugnant iterum tot diverſæ rerum naturæ, quales
ſunt aves, limaces, ſaxa, ſagittæ, nives, fumi, grandines, piſces,
&c. quæ tamen omnia ſpecie & genere differentia, moverentur à
naturâ ſuâ circulariter, ipſa naturis diverſiſſima, &c. [In Engliſh
thus] If the ſecond, (that is, if you ſhall ſay that this principle is
a ſubſtance) it is either matter, or form, or a compound of both.
But ſuch diverſe natures of things are again repugnant, ſuch as are
birds, ſnails, ſtones, darts, ſnows, ſmoaks, hails, fiſhes, &c. all
which notwithſtanding their differences in ſpecies and kind, are
moved of their own nature circularly, they being of their natures
moſt different, &c.
SALV. If theſe things before named are of diverſe natures, and
things of diverſe natures cannot have a motion in common, it muſt
follow, if you would give ſatisfaction to all, that you are to think
of, more than two motions onely of upwards and downwards: and
if there muſt be one for the arrows, another for the ſnails, another
for the ſtones, and another for fiſhes; then are you to bethink your
ſelf of worms, topazes and muſhrums, which are not leſs different
in nature from one another, than ſnow and hail.
SIMP. It ſeems that you make a jeſt of theſe Arguments.
SALV. No indeed, Simplicius, but it hath been already
ſwered above, to wit, that if one motion, whether downwards or
upwards, can agree with all thoſe things afore named, a circular
motion may no leſs agree with them: and as you are a
tick, do not you put a greater difference between an elementary
comet and a celeftial ſtar, than between a fiſh and a bird? and
yet both thoſe move circularly. Now propoſe your ſecond
gument.
SIMP. Si terra ſtaret per voluntatem Dei, rotaréntne cætera, an
non? ſi hoc, falſum eſt à naturâ gyrare; ſi illud, redeunt priores
quæſtiones. Et ſanè mirum eſſet, quòd Gavia piſciculo, Alauda
nidulo ſuo, & corvus limaci, petraque, etiam volans, imminere
non poſſet. [Which I thus render:] If the Earth be ſuppoſed to
ſtand ſtill by the will of God, ſhould the reſt of bodies turn round
or no? If not, then it's falſe that they are revolved by nature; if
the other, the former queſtions will return upon us. And
truly it would be ſtrange that the Sea-pie ſhould not be able to
hover over the ſmall fiſh, the Lark over her neſt, and the Crow
ver the ſnail and rock, though flying.
1
SALV. I would anſwer for my ſelf in general terms, that if
it were appointed by the will of God, that the Earth ſhould ceaſe
from its diurnal revolution, thoſe birds would do what ever ſhould
pleaſe the ſame Divine will. But if this Author deſire a more
particular anſwer, I ſhould tell him, that they would do quite
trary to what they do now, if whilſt they, being ſeparated from
the Earth, do bear themſelves up in the air, the Terreſtrial Globe
by the will of God, ſhould all on a ſudden be put upon a
tate motion; it concerneth this Author now to aſcertain us what
would in this caſe ſucceed.
SAGR. I pray you, Salviatus, at my requeſt to grant to this
Author, that the Earth ſtanding ſtill by the will of God, the other
things, ſeparated from it, would continue to turn round of their
own natural motion, and let us hear what impoſſibilities or
veniences would follow: for I, as to my own particular, do not
ſee how there can be greater diſorders, than theſe produced by the
Author himſelf, that is, that Larks, though they ſhould flie, could
not be able to hover over their neſts, nor Crows over ſnails, or
rocks: from whence would follow, that Crows muſt ſuffer for
want of ſnails, and young Larks muſt die of hunger, and cold, not
being able to be fed or ſheltered by the wings of the old ones.
This is all the ruine that I can conceive would follow, ſuppoſing
the Authors ſpeech to be true. Do you ſee, Simplicius, if
ter inconveniences would happen?
SIMP. I know not how to diſcover greater; but it is very
dible, that the Author beſides theſe, diſcovered other diſorders in
Nature, which perhaps in reverend reſpect of her, he was not
ing to inſtance in. Therefore let us proceed to the third
ction. Inſuper quî fit, ut istæ res tam variæ tantùm moveantur
ab Occaſu in Ortum, parallelæ ad Æquatorem? ut ſemper
tur, nunquam quieſcant? [which ſpeaks to this ſenſe:] Moreover,
how comes it to paſs that theſe things, ſo diverſe, are onely moved
from the Weſt towards the Eaſt, parallel to the Æquinoctial?
that they always move, and never reſt?
SALV. They move from Weſt to Eaſt parallel to the
noctial without ceaſing, in the ſame manner as you believe the
fixed ſtars to move from Eaſt to Weſt, parallel to the
al, without ever reſting.
SIMP. Quarè, quò ſunt altiores, celeriùs; quò humiliores,
diùs? (i. e.) Why are the higher the ſwifter, and the lower the
ſlower?
SALV. Becauſe that in a Sphere or circle, that turns about
on its own centre, the remoter parts deſcribe greater circuits, and
the parts nearer at hand deſcribe leſſer in the ſame time.
SIMP. Quare, quæ Æquinoctiali propriores, in majori; quæ
1remotiores, in minori circulo feruntur? [ſcilicet:] Why are
thoſe near the Æquinoctial carried about in a greater circle, and
thoſe which are remote in a leſſer?
SALV. To imitate the ſtarry Sphere, in which thoſe neareſt
to the Æquinoctial, move in greater circles, than the more
mote.
SIMP. Quarè Pila eadem ſub Æquinoctiali tota circa centrum
terr æ, ambitu maximo, celeritate incredibili; ſub Polo verò circa
centrum proprium, gyro nullo, tarditate ſupremâ volveretur?
[That is:] Why is the ſame ball under the Æquinoctial wholly
turned round the centre of the Earth in the greateſt
rence, with an incredible celerity; but under the Pole about its
own centre, in no circuite, but with the ultimate degree of
dity?
SALV. To imitate the ſtars of the Firmament, that would do
the like if they had the diurnal motion.
SIMP. Quare eadem res, pila v. g. plumbea, ſi ſemel terram
circuivit, deſcripto circulo maximo, eandem ubique non
migret ſecundùm circulum maximum, ſed tranſlata extra
ctialem in circulis minoribus agetur? [Which ſpeaketh thus:]
Why doth not the ſame thing, as for example, a ball of lead
turn round every where according to the ſame great circle, if once
deſcribing a great circle, it hath incompaſſed the Earth, but being
removed from the Æquinoctial, doth move in leſſer circles?
SALV. Becauſe ſo would, nay, according to the doctrine of
Ptolomey, ſo have ſome fixed ſtars done, which once were very
near the Æquinoctial, and deſcribed very vaſt circles, and now that
they are farther off, deſcribe leſſer.
SAGR. If I could now but keep in mind all theſe fine
tions, I ſhould think that I had made a great purchaſe; I muſt
needs intreat you, Simplicius, to lend me this Book, for there
not chuſe but be a ſea of rare and ingenious matters contained in
it.
SIMP. I will preſent you with it.
SAGR. Not ſo, Sir; I would not deprive you of it: but are
the Queries yet at an end?
SIMP. No Sir; hearken therefore. Si latio circularis
vibus & levibus eſt naturalis, qualis eſt ea quæ fit ſecundùm
am rectam? Nam ſi naturalis, quomodo & is motus qui circum est,
naturalis eſt, cùm ſpecie differat à recto? Si violentus, quî fit, ut
miſſile ignitum ſurſùm evolans ſcintilloſum caput ſurſùm à terrâ,
non autem circum volvatur, &c. [Which take in our idiom:] If
a circular lation is natural to heavy and light things, what is that
which is made according to a right line? For if it be natural, how
then is that motion which is about the centre natural, ſeeing it
1differs in ſpecies from a right motion? If it be violent, how is it
that a fiery dart flying upwards, ſparkling over our heads at a
ſtance from the Earth, but not turning about, &c.
Of the mixt
tion we ſee not the
part that is
lar, becauſe we
partake thereof.
SALV. It hath been ſaid already very often, that the circular
motion is natural to the whole, and to its parts, whilſt they are in
perfect diſpoſure, and the right is to reduce to order the parts
diſordered; though indeed it is better to ſay, that neither the
parts ordered or diſordered ever move with a right motion, but
with one mixed, which might as well be averred meerly circular:
but to us but one part onely of this motion is viſible and
vable, that is, the part of the right, the other part of the circular
being imperceptible to us, becauſe we partake thereof. And this
anſwers to the rays which move upwards, and round about, but we
cannot diſtinguiſh their circular motion, for that, with that we our
ſelves move alſo. But I believe that this Author never thought
of this mixture; for you may ſee that he reſolutely ſaith, that the
rays go directly upwards, and not at all in gyration.
SIMP. Quare centrum ſphære delapſæ ſub Æquatore ſpiram
ſcribit in ejus plano: ſub aliis parallelis ſpiram deſcribit in cono?
ſub Polo deſcendit in axe lineam gyralem, decurrens in ſuperficie
cylindricâ conſignatam? (In Engliſh to this purpoſe:) Why doth
the centre of a falling Globe under the Æquinoctial deſcribe a
ſpiral line in the plane of the Æquator; and in other parallels
a ſpiral about a Cone; and under the Pole deſcend in the
axis deſcribing a gyral line, running in a Cylindrical
cies?
SALV. Becauſe of the lines drawn from the Centre to the
cumference of the ſphere, which are thoſe by which graves
fcend, that which terminates in the Æquinoctial deſigneth a
cle, and thoſe that terminate in other parallels deſcribe conical
ſuperficies; now the axis deſcribeth nothing at all, but continueth
in its own being. And if I may give you my judgment freely, I
will ſay, that I cannot draw from all theſe Queries, any ſenſe that
interfereth with the motion of the Earth; for if I demand of this
Author, (granting him that the Earth doth not move) what would
follow in all theſe particulars, ſuppoſing that it do move, as
pernicus will have it; I am very confident, that he would ſay that
all theſe effects would happen, that he hath objected, as
niences to diſprove its mobility: ſo that in this mans opinion
ceſſary conſequences are accounted abſurdities: but I beſeech
you, if there be any more, diſpatch them, and free us ſpeedily
from this weariſom task.
SIMP. In this which follows he oppoſes Copernicus & his Sectators,
who affirm, that the motion of the parts ſeparated from their whole,
is onely to unite themſelves to their whole; but that the moving
1circularly along with the vertigenous diurnal revolution is
lutely natural: againſt which he objecteth, ſaying, that according
to theſe mens opinion; Si tota terra, unà cum aquâ in nihilum
redigeretur, nulla grando aut pluvia è nube decideret, ſed
raliter tantùm circumferetur, neque ignis ullus, aut igneum
deret, cùm illorum non improbabili ſententià ignis nullus ſit ſuprà.
[Which I tranſlate to this ſenſe:] If the whole Earth, together
with the Water were reduced into nothing, no hail or rain would
fall from the clouds, but would be onely naturally carried round;
neither any fire or fiery thing would aſcend, ſeeing to theſe that men
it is no improbable opinion that there is no fire above.
SALV. The providence of this Philoſopher is admirable, and
worthy of great applauſe, for he is not content to provide for
things that might happen, the courſe of Nature continuing, but
will ſhew hic care in what may follow from thoſe things that he
very well knows ſhall never come to paſs. I will grant him
fore, (that I may get ſom pretty paſſages out of him) that if the
Earth and Water ſhould be reduced to nothing, there would be no
more hails or rains, nor would igneal matters aſcend any longer
upwards, but would continually turn round: what will follow?
what will the Philoſopher ſay then?
SIMP. The objection is in the words which immediately
low; here they are: Quibus tamen experientia & ratio
ſatur. Which nevertheleſs (ſaith he) is contrary to experience and
reaſon.
SALV. Now I muſt yield, ſeeing he hath ſo great an
tage of me as experience, of which I am unprovided. For as yet
I never had the fortune to ſee the Terreſtrial Globe and the
ment of Water turn'd to nothing, ſo as to have been able to
ſerve what the hail and water did in that little Chaos. But he
perhaps tells us for our inſtruction what they did.
SIMP. No, he doth not.
SALV. I would give any thing to change a word or two with
this perſon, to ask him, whether when this Globe vaniſhed, it
ried away with it the common centre of gravity, as I believe it did;
in which caſe, I think that the hail and water would remain
ſate and ſtupid amongſt the clouds, without knowing what to do
with themſelves. It might be alſo, that attracted by that great
void Vacuum, left by the Earths abſenting, all the ambients would
be rarified, and particularly, the air, which is extreme eaſily drawn,
and would run thither with very great haſte to fill it up. And
perhaps the more ſolid and material bodies, as birds, (for there
would in all probability be many of them ſcattered up and down
in the air) would retire more towards the centre of the great
cant ſphere; (for it ſeemeth very reaſonable, that ſubſtances that
1under ſmall bulk contain much matter, ſhould have narrower
ces aſſigned them, leaving the more ſpacious to the more rarified)
and there being dead of hunger, and reſolved into Earth, would
form a new little Globe, with that little water, which at that time
was among the clouds. It might be alſo, that thoſe matters as
not beholding the light, would not perceive the Earths departure,
but like blind things, would deſcend according to their uſual cuſtom
to the centre, whither they would now go, if that globe did not
hinder them. And laſtly, that I may give this Philoſopher a leſs
irreſolute anſwer, I do tell him, that I know as much of what
would follow upon the annihilation of the Terreſtrial Globe, as
he would have done that was to have followed in and about the
ſame, before it was created. And becauſe I am certain he will
ſay, that he would never have been able to have known any of
all thoſe things which experience alone hath made him knowing
in, he ought not to deny me pardon, and to excuſe me if I know
not that which he knows, touching what would enſue upon the
annihilation of the ſaid Globe: for that I want that experience
which he hath. Let us hear if he have any thing elſe to ſay.
SIMP. There remains this figure, which repreſents the
ſtrial Globe with a great cavity about its centre, full of air; and
to ſhew that Graves move not downwards to unite with the
reſtrial Globe, as Copernicus ſaith, he conſtituteth this ſtone in
the centre; and demandeth, it being left at liberty, what it would
do; and he placeth another in the ſpace of this great vacuum, and
asketh the ſame queſtion. Saying, as to the firſt: Lapis in centro
conſtitutus, aut aſcendet ad terram in punctum aliquod, aut non. Si
ſecundum; falſum est, partes ob ſolam ſejunctionem à toto, ad
lud moveri. Si primum; omnis ratio & experientia renititur,
neque gravia in ſuœ gravitatis centro conquieſcent. Item ſi
ſpenſus lapis, liberatus decidat in centrum, ſeparabit ſe à toto,
tra Copernicum: ſi pendeat, refragatur omnis experientia, cùm
videamus integros fornices corruere. (Wherein he ſaith:) The
ſtone placed in the centre, either aſcendeth to the Earth in ſome
point, or no. If the ſecond, it is falſe that the parts ſeparated
from the whole, move unto it. If the firſt; it contradicteth all
reaſon and experience, nor doth the grave body reſt in the centre
of its gravity. And if the ſtone being ſuſpended in the air, be let
go, do deſcend to the centre, it will ſeparate from its whole,
trary to Copernicus: if it do hang in the air, it contradicteth all
experience: ſince we ſee whole Vaults to fall down.
SALV. I will anſwer, though with great diſadvantage to my
ſelf, ſeeing I have to do with one who hath ſeen by experience,
what theſe ſtones do in this great Cave: a thing, which for my
part I have not ſeen; and will ſay, that things grave have an
1ſtence before the common centre of gravity: ſo that it is not one

centre alone, which is no other than indiviſible point, and therefore
of no efficacie, that can attract unto it grave matters; but that thoſe
matters conſpiring naturally to unite, form to themſelves a
mon centre, which is that about which parts of equal moment
conſiſt: ſo that I hold, that if the great aggregate of grave

dies were gathered all into any one place, the ſmall parts that were
ſeparated from their whole, would follow the ſame, and if they
were not hindered, would penetrate wherever they ſhould find
parts leſs grave than themſelves: but coming where they ſhould
meet with matters more grave, they would deſcend no farther.
And therefore I hold, that in the Cave full of air, the whole Vault
would preſs, and violently reſt it ſelf onely upon that air, in caſe
its hardneſs could not be overcome and broken by its gravity; but
looſe ſtones, I believe, would deſcend to the centre, and not ſwim
above in the air: nor may it be ſaid, that they move not to their
whole, though they move whither all the parts of the whole
would transfer themſelves, if all impediments were removed.
Things grave are
before the centre of
gravity.
The great maſs
of grave bodies
ing transferred out
of their place, the
ſeparated parts
would follow that
maß.
SIMP. That which remaineth, is a certain Errour which he
ſerveth in a Diſciple of Copernicus, who making the Earth to
move with an annual motion, and a diurnal, in the ſame manner
as the Cart-wheel moveth upon the circle of the Earth, and in it
ſelf, did conſtitute the Terreſtrial Globe too great, or the great
Orb too little; for that 365 revolutions of the Æquinoctial, are
leſs by far than the circumference of the great Orb.
SALV. Take notice that you miſtake, and tell us the direct
contrary to what muſt needs be written in that Book; for you
ſhould ſay, that that ſame Copernican Author did conſtitute the
Terreſtrial Globe too little, and the great Orb too big; and not
the Terreſtrial Globe too big, and the annual too little.
SIMP. The miſtake is not mine; ſee here the words of the
Book. Non videt, quòd vel circulum annuum æquo minorem, vel
orbem terreum juſto multò fabricet majorem. (In Engliſh thus:)
He ſeeth not, that he either maketh the annual circle equal to the
leſs, or the Terreſtrial Orb much too big.
SALV. I cannot tell whether the firſt Author erred or no, ſince
the Author of this Tractate doth not name him; but the error of
this Book is certain and unpardonable, whether that follower of
Copernicus erred or not erred; for that your Author paſſeth by ſo
material an error, without either detecting or correcting it. But
let him be forgiven this fault, as an error rather of inadvertencie,
than of any thing elſe: Farthermore, were it not, that I am
ready wearied and tired with talking and ſpending ſo mnch time
with very little profit, in theſe frivolous janglings and
tions, I could ſhew, that it is not impoſſible for a circle, though
1
no bigger than a Cart-wheel, with making not 365, but leſſe than
20 revolutions, to deſcribe and meaſure the circumference, not
onely of the grand Orb, but of one a thouſand times greater;
and this I ſ y to ſhew, that there do not want far greater
ties, than this wherewith your Author goeth about to detect the
errour of Copernicus: but I pray you, let us breath a little, that
ſo we may proceed to the other Philoſopher, that oppoſeth of the
ſame Copernicus.
It is not
ble with the
cumference of a
ſmall circle few
times revolved to
meaſure and
ſcribe a line bigger
than any great
cle what ſoever.
SAGR. To confeſſe the truth, I ſtand as much in need of
ſpite as either of you; though I have onely wearied my eares:
and were it not that I hope to hear more ingenious things from
this other Author, I queſtion whether I ſhould not go my ways, to

take the air in my ^{*} Pleaſure-boat.
Gondola.
SIMP. I believe that you will hear things of greater moment;
for this is a moſt accompliſhed Philoſopher, and a great
tician, and hath confuted Tycho in the buſineſſe of the Comets,
and new
* The name of
the Author is
pie Claramontius.
SALV. Perhaps he is the ſame with the Author of the Book,
called Anti-Tycho?
SIMP. He is the very ſame: but the confutation of the new
Stars is not in his Anti-Tycho, onely ſo far as he proveth, that they
were not prejudicial to the inalterability and ingenerability of the
Heavens, as I told you before; but after he had publiſhed his
Anti-Tycho, having found out, by help of the Parallaxes, a way to
demonſtrate, that they alſo are things elementary, and contained
within the concave of the Moon, he hath writ this other Book,
de tribus uovis Stellis, &c. and therein alſo inſerted the
ments againſt Copernicus: I have already ſhewn you what he
harh written touching theſe new Stars in his Anti-Tycho, where he
denied not, but that they were in the Heavens; but he proved, that
their production altered not the inalterability of the Heavens, and
that he did, with a Diſcourſe purely philoſophical, in the ſame man
ner as you have already heard. And I then forgot to tell you, how
that he afterwards did finde out a way to remove them out of the
Heavens; for he proceeding in this confutation, by way of
putations and parallaxes, matters little or nothing at all
ſtood by me, I did not mention them to you, but have bent all my
ſtudies upon theſe arguments againſt the motion of the Earth,
which are purely natural.
SALV. I underſtand you very well: and it will be convenient
after we have heard what he hath to ſay againſt Copernicus, that
we hear, or ſee at leaſt the manner wherewith he, by way of
rallaxes, proveth thoſe new ſtars to be elementary, which ſo many
famous Aſtronomers conſtitute to be all very high, and amongſt
the ſtars of the Firmament; and as this Author accompliſheth ſuch
1an enterprize of pulling the new ſtars out of heaven, and placing
them in the elementary Sphere, he ſhall be worthy to be highly
exalted, and transferred himſelf amongſt the ſtars, or at leaſt,
that his name be by fame eternized amongſt them. Yet before we
enter upon this, let us hear what he alledgeth againſt the opinion
of Copernicus, and do you begin to recite his Arguments.
SIMP. It will not be neceſſary that we read them ad verbum,
becauſe they are very prolix; but I, as you may ſee, in reading
them ſeveral times attentively, have marked in the margine thoſe
words, wherein the ſtrength of his arguments lie, and it will
ſuffice to read them. The ſirſt Argument beginneth here. Et

primo, ſi opinio Copernici recipiatur, Criterium naturalis
ſophiæ, ni prorſus tollatur, vehementer ſaltem labefactari
videtur. [In our Idiom thus] And firſt, if Copernicus his opinion
be imbraced, the Criterium of natural Philoſophy will be, if not
wholly ſubverted, yet at leaſt extreamly ſhaken.
The opinion of
Copernicus
throws the
rium of Philoſophy
Which, according to the opinion of all the ſects of Philoſophers
requireth, that Senſe and Experience be our guides in
ting: But in the Copernican poſition the Senſes are greatly
ded, whil'ſt that they viſibly diſcover neer at hand in a pure
um, the graveſt bodies to deſcend perpendicularly downwards,
ver deviating a ſingle hairs breadth from rectitude; and yet
ding to the opinion of Copernicus, the ſight in ſo manifeſt a thing
is deceived, and that motion is not reall ſtraight, but mixt of
right and circular.
SALV. This is the firſt argument, that Ariſtotle, Ptolomy, and
all their followers do produce; to which we have
ly anſwered, and ſhewn the Paralogiſme, and with ſufficient
plainneſſe proved, that the motion in common to us and other
veables, is, as if there were no ſuch thing; but becauſe true
cluſions meet with a thouſand accidents, that confirme them, I

will, with the favour of this Philoſopher, adde ſomething more;
and you Simplicius perſonating him, anſwer me to what I ſhall
ask you: And firſt tell me, what effect hath that ſtone upon you,

which falling from the top of the Tower, is the cauſe that you
ceive that motion; for if its fall doth operate upon you neither
more nor leſſe, than its ſtanding ſtill on the Towers top, you
doubtleſſe could not diſcern its deſcent, or diſtinguiſh its moving
from its lying ſtill.
Common motion
is, as if it never
were.
The argument
taken from things
falling
larly, another way
confuted.
SIMP. I comprehend its moving, in relation to the Tower,
for that I ſee it one while juſt againſt ſuch a mark in the ſaid
Tower, and another while againſt another lower, and ſo
ſively, till that at laſt I perceive it arrived at the ground.
SALV. Then if that ſtone were let fall from the tallons of an
Eagle flying, and ſhould deſcend thorow the ſimple inviſible Air,
1and you had no other object viſible and ſtable, wherewith to make
compariſons to that, you could not perceive its motion?
SIMP. No, nor the ſtone it ſelf; for if I would ſee it, when

it is at the higheſt, I muſt raiſe up my head, and as it deſcendeth
I muſt hold it lower and lower, and in a word, muſt continually
move either that, or my eyes, following the motion of the ſaid
ſtone.
Whence the
tion of a cadent
dy is collected.
SALV. You have now rightly anſwered: you know then that

the ſtone lyeth ſtill, when without moving your eye, you alwayes
ſee it before you; and you know that it moveth, when for the
keeping it in ſight, you muſt move the organ of ſight, the eye. So
then when ever without moving your eye, you continually
hold an object in the ſelf ſame aſpect, you do always judge it
immoveable.
The motion of
the eye argueth
the motion of the
object looked on.
SIMP. I think it muſt needs be ſo.
SALV. Now fancy your ſelf to be in a ſhip, and to have fixed
your eye on the point of the Sail-yard: Do you think, that
cauſe the ſhip moveth very faſt, you muſt move your eye, to keep
your ſight alwayes upon the point of the Sail-yard, and to
low its motion?
SIMP. I am certain, that I ſhould need to make no change at
all; and that not only in the ſight; but if I had aimed a Musket
at it, I ſhould never have need, let the ſhip move how it will,
to ſtir it an hairs breadth to keep it full upon the ſame.
SALV. And this happens becauſe the motion, which the Ship
conferreth on the Sail-yard, it conferreth alſo upon you, and upon
your eye; ſo that you need not ſtir it a jot to behold the top of
the Sail-yard: and conſequently, it will ſeem to you
able. Now this Diſcourſe being applied to the revolution of the
Earth, and to the ſtone placed in the top of the Tower, in which
you cannot diſcern any motion, becauſe that you have that
tion which is neceſſary for the following of it, in common with it
from the Earth; ſo that you need not move your eye. When
gain there is conferred upon it the motion of deſcent, which is its
particular motion, and not yours, and that it is intermixed with the
circular, that part of the circular which is common to the ſtone,
and to the eye, continueth to be imperceptible, and the right
ly is perceived, for that to the perception of it, you muſt follow it
with your eye, looking lower and lower. I wiſh for the
ving of this Philoſopher, that I could adviſe him, that ſome time

or other going by water, he would carry along with him a Veſſel
of reaſonable depth full of water, and prepare a ball of wax, or
other matter that would deſcend very ſlowly to the bottome, ſo
that in a minute of an hour, it would ſcarce ſink a yard; and that
rowing the boat as faſt as could be, ſo that in a minute of an hour
1it ſhould run above an hundred yards, he would let the ball
merge into the water, & freely deſcend, & diligently obſerve its
tion. If he would but do thus, he ſhould ſee, firſt, that it would go in a
direct line towards that point of the bottom of the veſſel, whither it
would tend, if the boat ſhould ſtand ſtill; & to his eye, and in
tion to the veſſel, that motion would appear moſt ſtraight and
pendicular, and yet he could not ſay, but that it would be compoſed
of the right motion downwards, and of the circular about the
ment of water. And if theſe things befall in matters not natural,
and in things that we may experiment in their ſtate of reſt; & then
again in the contrary ſtate of motion, and yet as to appearance no
diverſity at all is diſcovered, & that they ſeem to deceive our ſenſe
what can we diſtinguiſh touching the Earth, which hath been
petually in the ſame conſtitution, as to motion and reſt? And in
what time can we experiment whether any difference is diſcernable
amongſt theſe accidents of local motion, in its diverſe ſtates of
tion and reſt, if it eternally indureth in but one onely of them?
An experiment
that ſheweth how
the common motion
is imperceptible.
SAGR. Theſe Diſcourſes have ſomewhat whetted my ſtomack,
which thoſe fiſhes, and ſnails had in part nauſeated; and the former
made me call to minde the correction of an errour, that hath ſo
much appearance of truth, that I know not whether one of a
thouſand would refuſe to admit it as unqueſtionable. And it was
this, that ſailing into Syria, and carrying with me a very good
Teleſcope, that had been beſtowed on me by our Common Friend,
who not many dayes before had invented, I propoſed to the
riners, that it would be of great benefit in Navigation to make uſe
of it upon the round top of a ſhip, to diſcover and kenne Veſſels
afar off. The benefit was approved, but there was objected the

difficulty of uſing it, by reaſon of the Ships continual fluctuation;
and eſpecially on the round top, where the agitation is ſo much
greater, and that it would be better for any one that would make
uſe thereof to ſtand at the Partners upon the upper Deck, where
the toſſing is leſſe than in any other place of the Ship. I (for I
will not conceal my errour) concurred in the ſame opinion, and
for that time ſaid no more: nor can I tell you by what hints I was
moved to return to ruminate with my ſelf upon this buſineſſe, and
in the end came to diſcover my ſimplicity (although excuſable) in
admitting that for true, which is moſt falſe; falſe I ſay, that the
great agitation of the basket or round top, in compariſon of the
ſmall one below, at the partners of the Maſt, ſhould render the
uſe of the Teleſcope more difficult in finding out the object.
An ingenuous
conſideration
bout the poſſibility
of uſing the
cope with as much
facility on the
round top of the
Maſt of a ſhip,
as on the Deck.
SALV. I ſhould have accompanied the Mariners, and your ſelf
at the beginning.
SIMP. And ſo ſhould I have done, and ſtill do: nor can I
lieve, if I ſhould think of it an hundred years, that I could
ſtand it otherwiſe.
1
SAGR. I may then, it ſeems, for once prove a Maſter to you both.
And becauſe the proceeding by interrogatories doth in my opinion
much dilucidate things, beſides the pleaſure which it affords of
founding our companion, forcing from him that which he thought he
knew not, I will make uſe of that artifice. And firſt, I ſuppoſe that the
Ship, Gally, or other Veſſel, which we would diſcover, is a great way
off, that is, four, ſix, ten, or twenty ^{*} miles, for that to kenne thoſe

neer at hand there is no need of theſe Glaſſes: & conſequently, the
Teleſcope may at ſuch a diſtance of four or ſix miles conveniently
diſcover the whole Veſſel, & a muchgreater bulk. Now I demand
what for ſpecies, & how many for number are the motions that are
made upon the round top, depending on the fluctuation of the Ship.
* I deviate here
from the ſtrict Sea
Diallect, which
denominatesall
ſtances by Leagues.
SALV. We will ſuppoſe that the Ship goeth towards the Eaſt.
Firſt, in a calme Sea, it would have no other motion than

this of progreſſion, but adding the undulation of the Waves,
there ſhall reſult thence one, which alternately hoyſting and
ering the poop and prow, maketh the round top, to lean forwards
and backwards; other waves driving the veſſel ſidewayes, bow the
Maſt to the Starboard and Larboard; others, may bring the ſhip
ſomewhat abovt, and bear her away by the Miſne from Eaſt, one

while towards the ^{*} Northeaſt; another while toward the
eaſt; others bearing her up by the Carine may make her onely to
riſe, and fall; and in ſum, theſe motions are for ſpecies two, one
that changeth the direction of the Teleſcope angularly, the other
lineally, without changing angle, that is, alwayes keeping the
tube of the Inſtrument parallel to its ſelf.
Different
ons depending on
the fluctuation of
the Ship.
* Greco, which
the Latine
ſlator according to
his uſual
neſſe (to call it no
worſe) tranſlates
Corum Ventum,
the Northweſt
Wind, for Ventum
Libanotum.
SAGR. Tell me, in the next place, if we, having firſt directed

the Teleſcope yonder away towards the Tower of ^{*} Burano, ſix
miles from hence, do turn it angularly to the right hand, or to the
left, or elſe upwards or downwards, but a ^{*}ſtraws breadth, what

fect ſhall it have upon us touching the finding out of the ſaid tower?
Two mutations
made in the
ſcope, depending on
the agitation of the
Ship.
* This is a Caſtle
ſix Italian miles
from Venice
Northwards.
SALV. It would make us immediately loſe ſight of it, for ſuch
a declination, though ſmall here, may import there hundreds and

thouſands of yards.
* Vnnerod'
na, the black or
paring of a nail.
SAGR. But if without changing the angle, keeping the tube
alwayes parallel to it ſelf, we ſhould transfer it ten or twelve
yards farther off to the right or left hand, upwards or downwards,
what alteration would it make as to the Tower?
SALV. The change would be abſolutely undiſcernable; for
that the ſpaces here and there being contained between parallel
rayes, the mutations made here and there, ought to be equal, and
becauſe the ſpace which the Inſtrument diſcovers yonder, is
ble of many of thoſe Towers; therefore we ſhall not loſe ſight of it.
SAGR. Returning now to the Ship, we may undoubtedly
firm, that the Teleſcope moving to the right or left, upwards, or
1downwards, and alſo forwards or backwards ten or fifteen fathom,
keeping it all the while parallel to its ſelf, the viſive ray cannot
ſtray from the point obſerved in the object, more than thoſe
teen fathom; and becauſe in a diſtance of eight or ten miles, the
Inſtrument takes in a much greater ſpace than the Gally or other
Veſſel kenn'd; therefore that ſmall mutation ſhall not make me
loſe ſight of her. The impediment therefore, and the cauſe of
loſing the object cannot befall us, unleſſe upon the mutation made
angularly; ſince that Teleſcopes tranſportation higher or lower, to
the right, or to the left, by the agitation of the ſhip, cannot import
any great number of fathomes. Now ſuppoſe that you had two
Teleſcopes fixed, one at the Partners cloſe by the Deck, and the
ther at the round top, nay at the main top, or main top-gallant
top, where you hang forth the Pennon or ſtreamer, and that they
be both directed to the Veſſel that is ten miles off, tell me,
ther you believe that any agitation of the ſhip, & inclination of the
Maſt, can make greater changes, as to the angle, in the higher tube,
than in the lower? One wave ariſing, the prow will make the main
top give back fifteen or twenty fathom more than the foot of the
Maſt, and it ſhall carry the upper tube along with it ſo greata ſpace,
& the lower it may be not a palm; but the angle ſhall change in one
Inſtrument aſwell as in the other; and likewiſe a ſide-billow ſhall
bear the higher tube an hundred times as far to the Larboard or
Starboard, as it will the other below; but the angles change not at
all, or elſe alter both alike. But the mutation to the right hand or
left, forwards or backwards, upwards or downwards, bringeth no
ſenſible impediment in the kenning of objects remote, though the
alteration of the angle maketh great change therein; Therefore it
muſt of neceſſity be confeſſed, that the uſe of the Teleſcope on the
round top is no more difficult than upon the Deck at the Partners;
ſeeing that the angular mutations are alike in both places.
SALV. How much circumſpection is there to be uſed in affirming
or denying a propoſition? I ſay again, thar hearing it reſolutely
med, that there is a greater motion made on the Maſts top, than at
its partners, every one will perſwade himſelf, that the uſe of the
leſcope is much more difficult above than below. And thus alſo I w
ill excuſe thoſe Philoſophers, who grow impatient and fly out into
paſſion againſt ſuch as will not grant them, that that Cannon bullet
which they cleerly ſee to fall in a right line perpendicularly, doth
abſolutely move in that manner; but will have its motion to be by
an arch, and alſo very much inclined and tranſverſal: but let us
leave them in theſe labyrinths, and let us hear the other objections,
that our Author in hand brings againſt Copernicus.
SIMP. The Author goeth on to demonſtrate that in the
ctrine of Copernicus, it is requiſite to deny the Senſes, and the
1greateſt Senſations, as for inſtance it would be, if we that feel the

reſpirations of a gentle gale, ſhould not feel the impulſe of a
petual winde that beateth upon us with a velocity that runs more
than 2529 miles an hour, for ſo much is the ſpace that the centre
of the Earth in its annual motion paſſeth in an hour upon the
cumference of the grand Orb, as he diligently calculates; and
becauſe, as he ſaith, by the judgment of Copernicus, Cum terra
movetur circumpoſitus aër, motus tamen ejus, velocior licet ac
pidior celerrimo quocunque vento, à nohis non ſentiretur, ſed
ma tum tranquilitas reputaretur, niſi alius motus accederet. Quid
eſt verò decipi ſenſum, niſi hæc eſſet deceptio? [Which I make to
ſpeak to this ſenſe.] The circumpoſed air is moved with the Earth,
yet its motion, although more ſpeedy and rapid than the ſwifteſt
wind whatſoever, would not be perceived by us, but then would
be thought a great tranquillity, unleſſe ſome other motion ſhould
happen; what then is the deception of the ſenſe, if this be
not?
The annual
tion of the Earth
muſt cauſe a
petual and ſtrong
winde.
SALV. It muſt needs be that this Philoſopher thinketh, that
that Earth which Copernicus maketh to turn round, together with
the ambient air along the circumference of the great Orb, is not that
whereon we inhabit, but ſome other ſeparated from this; for that this
of ours carrieth us alſo along with it with the ſame velocity, as

ſo the circumjacent air: And what beating of the air can we feel,
when we fly with equal ſpeed from that which ſhould accoſt us?
This Gentleman forgot, that we no leſs than the Earth and air are
carried about, and that conſequently we are always touch'd by
one and the ſame part of the air, which yet doth not make us feel
it.
The air alwayes
touching us with
the ſame part of it
cannot make us
feel it.
SIMP. But I rather think that he did not ſo think; hear the
words which immediately follow. Præterea nos quoque rotamur
ex circumductione terræ &c.
SALV. Now I can no longer help nor excuſe him; do you
plead for him and bring him off, Simplicius.
SIMP. I cannot thus upon the ſudden think of an excuſe that
pleaſeth me.
SALV. Go to; take this whole night to think on it, and
fend him to morrow; in the mean time let us hear ſome other of
his objections.
SIMP. He proſecuteth the ſame Objection, ſhewing, that in the

way of Copernicus, a man muſt deny his own ſenſes. For that
this principle whereby we turn round with the Earth, either is
intrinſick to us, or external; that is, a rapture of that Earth; and
if it be this ſecond, we not feeling any ſuch rapture, it muſt be
confeſſed that the ſenſe of feeling, doth not feel its own object
touching it, nor its impreſſion on the ſenſible part: but if the
1ciple be intrinſecal, we ſhall not perceive a local motion that is
rived from our ſelves, and we ſhall never diſcover a propenſion
petually annexed to our ſelves.
He that will
low Copernicus,
must deny his
ſes.
SALV. So that the inſtance of this Philoſopher lays its ſtreſs
on this, that whether the principle by which we move round with
the Earth be either extern, or intern, yet however we muſt
ceive it, and not perceiving it, it is neither the one nor the other,
and therefore we move not, nor conſequently the Earth. Now I

ſay, that it may be both ways, and yet we not perceive the ſame.
And that it may be external, the experiment of the boat
bundantly ſatisſieth me; I ſay, ſuperabundantly, becauſe it being
in our power at all times to make it move, and alſo to make it
ſtand ſtill, and with great exactneſs to make obſervation, whether
by ſome diverſity that may be comprehended by the ſenſe of
ing, we can come to know whether it moveth or no, ſeeing that
as yet no ſuch ſcience is obtained: Will it then be any matter of
wonder, if the ſame accident is unknown to us on the Earth, the
which may have carried us about perpetually, and we, without our

being ever able to experiment its reſt? You, Simplicius, as I
lieve, have gone by boat many times to Padoua, and if you will
confeſs the truth, you never felt in your ſelf the participation of
that motion, unleſs when the boat running a-ground, or
tring ſome obſtacle, did ſtop, and that you with the other
gers being taken on a ſudden, were with danger over-ſet. It
would be neceſſary that the Terreſtrial Globe ſhould meet with
ſome rub that might arreſt it, for I aſſure you, that then you
would diſcern the impulſe reſiding in you, when it ſhould toſs you
up towards the Stars. It's true, that by the other ſenſes, but yet

aſſiſted by Reaſon, you may perceive the motion of the boat, that
is, with the ſight, in that you ſee the trees and buildings placed on
the ſhoar, which being ſeparated from the boat, ſeem to move the

contrary way. But if you would by ſuch an experiment receive
intire ſatisfaction in this buſineſs of the Terreſtrial motion, look
on the ſtars, which upon this reaſon ſeem to move the contrary
way. As to the wondering that we ſhould not feel ſuch a
ciple, ſuppoſing it to be internal, is a leſs reaſonable conceit; for
if we do not feel ſuch a one, that cometh to us from without,
and that frequently goeth away, with what reaſon can we expect
to feel it, if it immutably and continually reſides in us? Now let
us ſee what you have farther to allege on this argument.
Our motion may
be either interne or
externe, and yet
we never perceive
or feel it.
The motion of a
Boat inſenſible to
thoſe that are with
in it, as to the ſenſe
of feeling.
The boats
on is perceptible to
the ſight joyn'd
with reaſon.
The terreſtrial
motion collected
from the ſtars.
SIMP. Take this ſhort exclamation. Ex hac itaque opinione
neceſſe est diffidere noſtris ſenſibus, ut penitùs fall acibus vel ſtupidis
in ſenſilibus, etiam conjunctiſſimis, dijudicandis. Quam ergò
ritatem ſperare poſſumus à facultate adeò fallaci ortum trabentem?
[Which I render thus:] From this opinion likewiſe, we muſt of
1neceſſity ſuſpect our own ſenſes, as wholly fallible, or ſtupid in
judging of ſenſible things even very near at hand. What truth
therefore can we hope for, to be derived from ſo deceiveable a
culty?
SALV. But I deſire not to deduce precepts more profitable, or
more certain, learning to be more circumſpect and leſs confident
about that which at firſt bluſh is repreſented to us by the ſenſes,
which may eaſily deceive us. And I would not have this Author
trouble himſelf in attemptiug to make us comprehend by ſenſe,
that this motion of deſcending Graves is ſimply right, and of
no other kind; nor let him exclaim that a thing ſo clear, manifeſt,
and obvious ſhould be brought in queſtion; for in ſo doing, he
maketh others believe, that he thinketh thoſe that deny that
tion to be abſolutely ſtreight, but rather circular, the ſtone did
ſenſibly ſee it to move in an arch, ſeeing that he inviteth their ſenſes
more than their Reaſon, to judg of that effect: which is not true,
Simplicius, for like as I, that am indifferent in all theſe
ons, and onely in the manner of a Comedian, perſonate
cus in theſe our repreſentations, have never ſeen, nor thought
that I have ſeen that ſtone fall otherwiſe than perpendicularly,
ſo I believe, that to the eyes of all others it ſeemed to do the
ſame. Better it is therefore, that depoſing that appearance in
which all agree, we make uſe of our Reaſon, either to confirm the
reality of that, or to diſcover its fallacy.
SAGR. If I could any time meet with this Philoſopher, who
yet me thinks is more ſublime than the reſt of the followers of
the ſame doctrines, I would in token of my affection put him in
mind of an accident which he hath doubtleſs very often beheld;
from which, with great conformity to that which we now diſcourſe
of, it may be collected how eaſily one may be deceived by the bare
appearance, or, if you will, repreſentation of the ſenſe. And the
accident is, the Moons ſeeming to follow thoſe that walk the ſtreets
in the night, with a pace equal to theirs, whilſt they ſee it go
ding along the Roofs of houſes, upon which it ſheweth juſt like a
cat, that really running along the ridges of houſes, leaveth them
behind. An appearance that, did not reaſon interpoſe, would but
too manifeſtly delude the ſight.
SIMP. Indeed there want not experiments that render us

tain of the fallacy of the meer ſenſes; therefore ſuſpending ſuch
ſenſations for the preſent, let us hear the Arguments that follow
which are taken, as he ſaith, ex rerum naturâ. The firſt of which
is, that the Earth cannot of its own nature move with three
ons very different; or otherwiſe we muſt deny many manifeſt

Axioms. The firſt whereof is, that Omnïs effectus dependeat ab
aliquâ cauſâ; [i. e.] that every effect dependeth on ſome cauſe.
1The ſecond, that Nulla res ſeipſam producat; [i. e.] that nothing
produceth it ſelf: from whence it follows, that it is not
ble that the mover and moved ſhould be totally the ſame thing:
And this is manifeſt, not onely in things that are moved by an
trinſick mover; but it is gathered alſo from the principles
pounded, that the ſame holdeth true in the natural motion
dent on an intrinſick principle; otherwiſe, being that the mover,
as a mover, is the cauſe, and the thing moved, as moved, is the
effect, the ſame thing would totally be both the cauſe and effect.
Therefore a body doth not move its whole ſelf, that is, ſo as
that all moveth, and all is moved; but its neceſſary in the thing
moved to diſtinguiſh in ſome manner the efficient principle of the
motion, and that which with that motion is moved. The third
Axiom is, that in rebus quæ ſenſui ſubjiciuntur, unum, quatenus
unum, unam ſolam rem producat; i. e. That in things ſubject to
the ſenſes, one, as it is one, produceth but onely one thing: That
is, the ſoul in animals produceth its true divers operations, as the
ſight, the hearing, the ſmell, generation, &c. but all theſe with
ſeveral inſtruments. And in ſhort, in things ſenſible, the
ty of operations, is obſerved to derive it ſelf from the diverſity
that is in the cauſe. Now if we put all theſe Axioms together, it

will be a thing very manifeſt, that one ſimple body, as is the
Earth, cannot of its own nature move at the ſame time with
three motions, very divers: For by the foregoing ſuppoſitions,
all moveth not its ſelf all; it is neceſfary therefore to diſtinguiſh
in it three principles of its three motions; otherwiſe one and the
ſame principle would produce many motions; but if it contein in
it three principles of natural motions, beſides the part moved, it
ſhall not be a ſimple body, but compounded of three principle
movers, and of the part moved. If therefore the Earth be a

ple body, it ſhall not move with three motions; nay more, it will
not move with any of thoſe which Copernicus aſcribeth to it, it
being to move but with one alone, for that it is manifeſt, by the
reaſons of Ariſtotle, that it moveth to its centre, as its parts do
ſhew, which deſcend at right angles to the Earths Spherical
Surface.
Arguments
gainſt the Earths
motion taken, ex
rerum natura.
Three Axioms
that are ſuppoſed
manifeſt.
A ſimple body
as the Earth,
not move with
three ſeveral
ons.
The Earth
not move with any
of the motions
gned it by
cus.
SALV. Many things might be ſaid, and conſidered touching
the connection of this argument; but in regard that we can

ſolve it in few words, I will not at this time without need inlarge
upon it; and ſo much the rather, becauſe the ſame Author hath
furniſhed me with an anſwer, when he ſaith that from one ſole
ple in animals, there are produced divers operations; ſo that for
the preſent my anſwer ſhall be, that in the ſame manner the Earth
from one onely principle deriveth ſeveral operations.
Anſwers to the
arguments
ry to the Earths
motion, taken ex
rerum natura.
SIMP. But this anſwer will not at all ſatisfie the Author who
1makes the objection, yea, it is totally overthrown by that which
immediately after he addeth for a greater confirmation of his
ment, as you ſhall hear. He re-inforceth his argument, I ſay, with

another Axiome, which is this; That natura in rebus neceſſari is
nec deficiat, nec abundat: i.e. That nature in things neceſſary is
neither defective, nor ſuperfluous. This is obvious to the

vers of natural things, and chiefly of animals, in which, becauſe
they are to move with many motions, Nature hath made many
flexures, and hath thereunto commodiouſly knitted the parts for
motion, as to the knees, to the hips, for the inabling of living
creatures to go, and run at their pleaſure. Moreover in man he
hath framed many flexions, and joynts, in the elbow, and hand, to
enable them to perform many motions. From theſe things the

gument is taken againſt the threefold motion of the Earth. [
ther the Body, that is one, and continuate, without any manner of
knittings or flexions, can exerciſe divers motions, or cannot: If it
can without them, then in vain hath nature framed the flexures in
animals; which is contrary to the Axiome: but if it cannot
out them, then the Earth, one body, and continuate, and deprived of
flexures, and joynts, cannot of its own nature move with
ty of motions.] You ſee now how craftily he falls upon your an­
ſwer, as if he had foreſeen it.
A fourth
iome againſt the
motion of the Earth
Flexures
ſary in animals for
the diverſity of
their motions.
Another
ment againſt the
three fold motion of
the Earth.
SALV. Are you ſerious, or do you jeſt?
SIMP. I ſpeak it with the beſt judgment I have.
SALV. You muſt therefore ſee that you have as fortunate an
hand in defending the reply of this Philoſopher, againſt ſome
ther rejoynders made to him; therefore anſwer for him, I pray
you, ſeeing we cannot have him here. You firſt admit it for true,
that Nature hath made the joynts, flexures, and knuckles of
ving creatures, to the intent that they might move with ſnndry
and divers motions; and I deny this propoſition; and ſay, that
theſe flexions are made, that the animal may move one, or more

of its parts, the reſt remaining immoved: and I ſay, that as to the
ſpecies and differences of motions thoſe are of one kind alone, to
wit, all circular, and for this cauſe you ſee all the ends of the

veable bones to be convex or concave, and of theſe ſome are
rical, as are thoſe that are to move every way, as in the

joynt, the arme of the Enſigne doth, in diſplaying the Colours,
and that of the Falconer in bringing his Hawk to the lure; and
ſuch is the flexure of the elbow, upon which the hand turns round,
in boring with an augure: others are circular onely one way, and
as it were cylindrical, which ſerve for the members that bend

ly in one faſhion, as the joynts of the fingers one above another,
&c. But without more particular inductions, one only general
courſe may make this truth underſtood; and this is, that of a ſolid
1body that moveth, one of its extreams ſtanding ſtill without
ching place, the motion muſt needs be circular, and no other: and

becauſe in the living creatures moving, one of its members doth
not ſeparate from the other its conterminal, therefore that motion
is of neceſſity circular.
The Flexures in
animals are not
made for the
verſity of motions.
The motions of
animals are of one
ſort.
The ends of the
bones are all
tund.
It is
ted, that the ends
of the bones are of
neceſſity to be
tund.
The motions of
animals are all
circular.
SIMP. How can this be? For I ſee the animal move with an
hundred motions that are not circular, and very different from one
another, as to run, to skip, to climbe, to deſcend, to ſwim, and
many
Secondary
ons of animals
pendent on the firſt
SALV. Tis well: but theſe are ſecondary motions, depending
on the preceding motions of the joynts and flexures. Upon the
plying of the legs to the knees, and the thighs to the hips, which
are circular motions of the parts, is produced, as conſequents, the
skip, or running, which are motions of the whole body, and theſe
may poſſibly not be circular. Now becauſe one part of the ter­

reſtrial Globe is not required to move upon another part
able, but that the motion is to be of the whole body, there is no
need in it of flexures.
The Terreſtriall
Globe hath noe
need of flexures.
SIMP. This (will the aduerſary rejoyn) might be, if the
on were but one alone, but they being three, and thoſe very
ferent from each other, it is not poſſible that they ſhould concur in

an ^{*} articulate body.
* Without joynts
SALV. I verily believe that this would be the anſwer of the
Philoſopher. Againſt which I make oppoſition another way; and
ask you, whether you think that by way of joynts and flexures one
may adapt the terreſtrial Globe to the participation of three
rent circular motions? Do you not anſwer me? Seeing you are
ſpeechleſſe, I will undertake to anſwer for the Philoſopher, who
would abſolutely reply that they might; for that otherwiſe it
would have been ſuperfluous, and beſides the purpoſe to have
poſed to conſideration, that nature maketh the flexions, to the
end, the moveable may move with different motions; and that
therefore the terreſtrial Globe having no flexures, it cannot have
thoſe three motions which are aſcribed to it. For if he had
thought, that neither by help of flexures, it could be rendered apt
for ſuch motions, he would have freely affirmed, that the Globe
could not move with three motions. Now granting this, I intreat

you, and by you, if it were poſſible, that Philoſopher,
thor of the Argument, to be ſo courteous as to teach me in what
manner thoſe flexures ſhould be accommodated, ſo that thoſe
three motions might commodiouſly be excerciſed; and I grant you
four or ſix moneths time to think of an anſwer. As to me, it
eth that one principle onely may cauſe a plurality of motions in

the Terreſtrial Globe, juſt in the ſame manner that, as I told you
before, one onely principle with the help of various inſtruments
1produceth ſundry and divers motions in living creatures. And as
to the flexures there is no need of them, the motions being of the
whole, and not of ſome particular parts; and becauſe they are
to be circular, the meer ſpherical figure is the moſt perfect
lation or flection that can be deſired.
It is deſired to
know, by means of
what flexures and
joynts the
ſtrial Globe might
move with three
diverſe motions.
One only
ple may cauſe a
plurality of
ons in the Earth.
SIMP. The moſt that ought to be granted upon this, would be,
that it may hold true in one ſingle motion, but in three different
motions, in my opinion, and that of the Author, it is
ble; as he going on, proſecuting the objection, writes in the
lowing words. Let us ſuppoſe, with Copernicus, that the Earth
moveth of its own faculty, and upon an intrinſick principle from
Weſt to Eaſt in the plane of the Ecliptick; and again, that it alſo
by an intrinſick principle revolveth about its centre, from Eaſt to
Weſt; and for a third motion, that it of its own inclination
cteth from North to South, and ſo back again. It being a
nuate body, and not knit together with joints and flections, our
fancy and our judgment will never be able to comprehend, that
one and the ſame natural and indiſtinct principle, that is, that
one and the ſame propenſion, ſhould actuate it at the ſame inſtant
with different, and as it were of contrary motions. I cannot
lieve that any one would ſay ſuch a thing, unleſſe he had
took to maintain this poſition right or wrong.
SALV. Stay a little; and find me out this place in the Book.
Fingamus modo cum Copernico terram aliqua ſuâ vi, & ab indito
principio impelli ab Occaſu ad Ortum in Eclipticæ plano; tum
ſus revolvi ab indito etiam principio, circa ſuimet centrum, ab

Ortu in Occaſum; tertio deſlecti rurſus ſu opte nutu à
ne in Auſtrum, & viciſſim. I had thought, Simplicius, that
that you might have erred in reciting the words of the
thor, but now I ſee that he, and that very groſſely,
veth himſelf; and to my grief, I find that he hath ſet himſelf to
oppoſe a poſition, which he hath not well underſtood; for theſe
are not the motions which Copernicus aſſignes to the Earth.
Where doth he find that Copernicus maketh the annual motion
by the Ecliptick contrary to the motion about its own centre? It
muſt needs be that he never read his Book, which in an hundred
places, and in the very firſt Chapters affirmeth thoſe motions to
be both towards the ſame parts, that is from Weſt to Eaſt.
But without others telling him, ought he not of himſelf to
prehend, that attributing to the Earth the motions that are ta
ken, one of them from the Sun, and the other from the
mum wobile, they muſt of neceſſity both move one and the ſame

A groſſe error
of the oppoſer of
Copernicus.
A ſubtil and
withal ſimple
gument againſt
Copernicus.
SIMP. Take heed that you do not erre your ſelf, and
cus alſo. The Diurnal motion of the primum mobile, is it not from
1Eaſt to Weſt? And the annual motion of the Sun through the
Ecliptick, is it not on the contrary from Weſt to Eaſt? How
then can you make theſe motions being conferred on the Earth, of
contraries to become conſiſtents?
SAGR. Certainly, Simplicius hath diſcovered to us the original
cauſe of error of this Philoſopher; and in all probability he
would have ſaid the very ſame.
SALV. Now if it be in our power, let us at leaſt recover
Simplicius from this errour, who ſeeing the Stars in their riſing
to appear above the Oriental Horizon, will make it no difficult
thing to underſtand, that in caſe that motion ſhould not belong

to the Stars, it would be neceſſary to confeſſe, that the Horizon,
with a contrary motion would go down; and that conſequently
the Earth would reoolve in it ſelf a contrary way to that
with the Stars ſeem to move, that is from Weſt to Eaſt, which
is according to the order of the Signes of the Zodiack. As, in the
next place, to the other motion, the Sun being fixed in the
tre of the Zodiack, and the Earth moveable about its
rence, to make the Sun ſeem unto us to move about the ſaid
diack, according to the order of the Signes, it is neceſſary, that
the E arth move according to the ſame order, to the end that the
Sun may ſeem to us to poſſeſſe alwayes that degree in the Zodiack,
that is oppoſite to the degree in which we find the Earth; and thus
the Earth running, verbi gratia, through Aries, the Sun will
appear to run thorow Libra; and the Earth paſſing thorow the
ſigne Taurus, the Sun will paſſe thorow Scorpio, and ſo the
Earth going thorow Gemini, the Sun ſeemeth to go thorow
gittarius; but this is moving both the ſame way, that is
ing to the order of the ſignes; as alſo was the revolution of the
Earth about its own centre.
The error of the
Antagoniſt is
nifeſt, by
ring that the
nual and diurnal
motions belonging
to the Earth are
both one way, and
not contrary.
SIMP. I underſtand you very well, and know not what to
ledge in excuſe of ſo groſſe an error.
SALV. And yet, Simplicius, there is one yet worſe then this; and
it is, that he makes the Earth move by the diurnal motion about
its own centre from Eaſt to Weſt; and perceives not that if this
were ſo, the motion of twenty four hours appropriated by him
to the Univerſe, would, in our ſeeming, proceed from Weſt to
Eaſt; the quite contrary to that which we behold.
SIMP. Oh ſtrange! Why I, that have ſcarce ſeen the firſt
elements of the Sphere, would not, I am confident, have erred
ſo horribly.
SALV. Judg now what pains this Antagoniſt may be thought
to have taken in the Books of Copernicus, if he abſolutely invert

the ſenſe of this grand and principal Hypotheſis, upon which is
founded the whole ſumme of thoſe things wherein Copernicus
1diſſenteth from the doctrine of Ariſtotle and Ptolomy. As again,

to this third motion, which the Author aſſignes to the Terreſtrial
Globe, as the judgment of Copernicus, I know not which he would
mean thereby: it is not that queſtionleſſe, which Copernicus
cribes unto it conjunctly with the other two, annual and diurnal,
which hath nothing to do with declining towards the South and
North; but onely ſerveth to keep the axis of the diurnal
on continually parallel to it ſelf; ſo that it muſt be confeſt, that
either the Authour did not underſtand this, or that elſe he
bled it. But although this great miſtake ſufficeth to free us from
any obligation of a farther enquiry into his objections; yet
vertheleſſe I ſhall have them in eſteem; as indeed they deſerve to
be valued much before the many others of impertinent
niſts. Returning therefore to his objection, I ſay, that the two
motions, annual and diurnal, are not in the leaſt contrary, nay are
towards the ſame way, and therefore may depend on one and the
ſame principle. The third is of it ſelf, and voluntarily ſo
tial to the annual, that we need not trouble our ſelves (as I ſhall
ſhew in its place) to ſtudy for principles either internal or external,
from which, as from its cauſe, to make it produced.
By another
error it is ſeen that
the Antagoniſt had
but little ſtudied
Copernicus.
It is queſtioned,
whether the
nent underſtood
the third motion
aſſigned to the
Earth by
cus.
SAGR. I ſhall alſo, as being induced thereto by natural reaſon,
ſay ſomething to this Antagoniſt. He will condemn Copernicus,
unleſſe I be able to anſwer him to all objections, and to ſatisfie
him in all queſtions he ſhall ask; as if my ignorance were a
ſary argument of the falſhood of his Doctrine. But if this way of
condemning Writers be in his judgment legal, he ought not to
think it unreaſonable, if I ſhould not approve of Arîſtotle and
lomy, when he cannot reſolve, better than my ſelf, thoſe doubts
which I propound to him, touching their Doctrine. He asketh me,
what are the principles by which the Terreſtrial Globe is moved

with the Annual motion through the Zodiack, and with the
nal through the Equinoctial about its own axis. I anſwer, that
they are like to thoſe by which Saturn is moved about the
ack in thirty years, and about its own centre in a much ſhorter
time along the Equinoctial, as the collateral apparition and
cultation of its Globes doth evince. They are principles like to
thoſe, whereby he ſcrupleth not to grant, that the Sun runneth
row the Ecliptick in a year, and revolveth about its own centre
parallel to the Equinoctial in leſſe than a moneth, as its ſpots doth
ſenſibly demonſtrate. They are things like to thoſe whereby the
Medicean Stars run through the Zodiack in twelve years, and
all the while revolve in ſmall circles, and ſhort periods of time
bout Jupiter.
The ſame
ment anſwered by
examples of the
like motions in
ther cœleſtial
dies.
SIMP. This Author will deny all theſe things, as deluſions of
the fight, cauſed by the cryſtals of the Teleſcope.
1
SAGR. But this would be to draw a further inconvenience
on himſelf, in that he holdeth, that the bare eye cannot be
ved in judging of the right motion of deſcending graves, and yet
holds that it is deceived in beholding theſe other motions at ſuch
time as its viſive vertue is perfected, and augmented to thirty times
as much as it was before. We tell him therefore, that the Earth in
like manner partaketh of the plurality of motions: and it is
haps the ſame, whereby the Loadſtone hath its motion
wards, as grave, and two circular motions, one Horizontal, and the
other Vertical under the Meridian. But what more; tell me,
plicius, between which do you think this Author would put a
greater difference, 'twixt right and circular motion, or 'twixt
on and reſt?
SIMP. 'Twixt motion and reſt, certainly. And this is

feſt, for that circular motion is not contrary to the right, according
to Aristotle; nay, he granteth that they may mix with each
ther; which it is impoſſible for motion and reſt to do.
Motion and reſt
are more different
than right motion
and circular.
SAGR. Therefore its a propoſition leſſe improbable to place
in one natural body two internal principles, one to right motion,
and the other to circular, than two ſuch interne principles one to
motion, and the other to reſt. Now both theſe poſitions agree to

the natural inclination that reſideth in the parts of the Earth to
turn to their whole, when by violence they are divided from it;
and they onely diſſent in the operation of the whole: for the
ter of them will have it by an interne principle to ſtand ſtill, and
the former aſcribeth to it the circular motion. But by your
ceſſion, and the confeſſion of this Philoſopher, two principles, one
to motion, and the other to reſt, are incompatible together, like as
their effects are incompatible: but now this evenes not in the two
motions, right, and circular, which have no repugnance to each
other.
One may more
rationally aſcribe
to the Earth two
internal principles
to the right, and
circular motion,
than two to motion
and reſt.
SALV. Adde this more, that in all probability it may be that

the motion, that the part of the Earth ſeparated doth make whilſt
it returneth towards its whole, is alſo circular, as hath been
dy declared; ſo that in all reſpects, as far as concernes the preſent
caſe, Mobility ſeemeth more likely than Reſt. Now proceed,
Simplicius, to what remains.
The motion of
the parts of the
Earth returning to
their whole may be
circular.
SIMP. The Authour backs his Argument with producing
ther abſurdity, that is, that the ſame motions agree to Natures
treamly different; but experience ſheweth, that the operations

and motions of different natures, are different; and Reaſon
firmeth the ſame: for otherwiſe we ſhould have no way left to
know and diſtinguiſh of natures, if they ſhould not have their
particular motions and operations, that might guide us to the
knowledge of their ſubſtances.
1
The diverſity of
motions helpeth us
in knowing the
verſity of natures.
SAGR. I have twice or thrice obſerved in the diſcourſes of this
Authour, that to prove that a thing is ſo, or ſo, he ſtill alledgeth,
that in that manner it is conformable with our underſtanding; or
that otherwiſe we ſhould never be able to conceive of it; or that
the Criterium of Philoſophy would be overthrown. As if that

ture had firſt made mens brains, and then diſpoſed all things in
conformity to the capacity of their intellects. But I incline rather
to think that Nature firſt made the things themſelves, as ſhe beſt
liked, and afterwards framed the reaſon of men capable of
ceiving (though not without great pains) ſome part of her
crets.
Nature firſt
made things as ſhe
pleaſed, and
wards capacitated
mens
ings for conceiving
of them.
SALV. I am of the ſame opinion. But tell me, Simplicius,
which are theſe different natures, to which, contrary to
rience and reaſon, Copernicus aſſignes the ſame motions and
rations.
SIMP. They are theſe. The Water, the Air, (which
leſſe are Natures different from the Earth) and all things that
are in thoſe elements compriſed, ſhall each of them have thoſe
three motions, which Copernicus pretends to be in the Terreſtriall
Globe; and my Authour proceedeth to demonſtrate

cally, that, according to the Copernican Doctrine, a cloud that is
ſuſpended in the Air, and that hangeth a long time over our
heads without changing place, muſt of neceſſity have all thoſe three
motions that belong to the Terreſtrial Globe. The
tion is this, which you may read your ſelf, for I cannot repeat it
without book.
Copernicus
roneouſly aſſigneth
the ſame operations
to different natures
SALV. I ſhall not ſtand reading of it, nay I think it an
tinency in him to have inſerted it, for I am certain, that no
Copernican will deny the ſame. Therefore admitting him what he
would demonſtrate, let us ſpeak to the objection, which in my
judgment hath no great ſtrength to conclude any thing contrary
to the Copernican Hypotheſis, ſeeing that it derogates nothing from
thoſe motions, and thoſe operations, whereby we come to the
knowledge of the natures, &c. Anſwer me, I pray you,
us: Thoſe accidents wherein ſome things exactly concur, can
they ſerve to inform us of the different natures of thoſe
From commune
accidents one
not know different
natures.
SIMP. No Sir: nay rather the contrary, for from the idendity
of operations and of accidents nothing can be inferred, but an
idendity of natures.
SALV. So that the different natures of the Water, Earth, Air,
and other things conteined in theſe Elements, is not by you
ed from thoſe operations, wherein all theſe Elements and their
fixes agree, but from other operations; is it ſo?
SIMP. The very ſame.
SALV. So that he who ſhould leave in the Elements all thoſe
1motions, operations, and other accidents, by which their natures
are diſtinguiſhed, would not deprive us of the power of coming
to the knowledge of them; although he ſhould remove thoſe
perations, in which they unitedly concur, and which for that reaſon
are of no uſe for the diſtinguiſhing of thoſe natures.
SIMP. I think your diſſertation to be very good.
SALV. But that the Earth, Water, Air, are of a nature equally
conſtituted immoveable about the centre, is it not the opinion of
your ſelf, Ariſtotle, Prolomy, and all their ſectators?
SIMP. Its on all hands granted as an undeniable truth.
SALV. Then from this common natural condition of
cence about the centre, there is no argument drawn of the different
natures of theſe Elements, and things elementary, but that
knowledge muſt be collected from other qualities not common;
and therefore whoſo ſhould deprive the Elements of this common
reſt only, and ſhould leave unto them all their other operations,
would not in the leaſt block up the way that leadeth to the
ledge of their eſſences. But Copernicus depriveth them onely of
this common reſt, and changeth the ſame into a common motion,
leaving them gravity, levity, the motions upwards, downwards,

ſlower, faſter, rarity, denſity, the qualities of hot, cold, dry, moiſt,
and in a word, all things beſides. Therefore ſuch an abſurdity, as
this Authour imagineth to himſelf, is no Copernican poſition; nor
doth the concurrence in an identity of motion import any more or
leſs, than the concurrence in an identity of reſt about the
fying, or not diverſifying of natures. Now tell us, if there be any
argument to the contrary.
The concurrence
of the Elements in
a common motion
importeth no more
or leſſe, than their
concurrence in a
common reſt.
SIMP. There followeth a fourth objection, taken from a

ral obſervation, which is, That bodies of the ſame kind, have
tions that agree in kinde, or elſe they agree in reſt. But by the
pernican Hypotheſis, bodies that agree in kinde, and are moſt ſem-

blable to one another, would be very diſcrepant, yea diametrically
repugnant as to motion; for that Stars ſo like to one another, would
be nevertheleſſe ſo unlike in motion, as that ſix Planets would
tually turn round; but the Sun and all the fixeed Stars would ſtand
perpetually immoveable.
A fourth
ment againſt
pernicus.
Bodies of the
ſame kinde have
motions that agree
in kinde.
SALV. The forme of the argument appeareth good; but yet
I believe that the application or matter is defective: and if the
Authour will but perſiſt in his aſſumption, the conſequence ſhall
make directly againſt him. The Argument runs thus; Amongſt
mundane bodies, ſix there are that do perpetually move, and they

are the ſix Planets; of the reſt, that is, of the Earth, Sun, and
fixed Stars, it is diſputable which of them moveth, and which
ſtands ſtill, it being neceſſary, that if the Earth ſtand ſtill, the Sun
and ſixed Stars do move; and it being alſo poſſible, that the Sun
1and fixed Stars may ſtand immoveable, in caſe the Earth ſhould
move: the matter of fact in diſpute is, to which of them we may
with moſt convenience aſcribe motion, and to which reſt. Natural
reaſon dictates, that motion ought to be aſſigned to the bodies,
which in kind and eſſence moſt agree with thoſe bodies which do
undoubtedly move, and reſt to thoſe which moſt diſſent from them;
and in regard that an eternal reſt and perpetual motion are moſt
different, it is manifeſt, that the nature of the body always
able ought to be moſt different from the body alwayes ſtable.
Therefore, in regard that we are dubious of motion and reſt,
let us enquire, whether by the help of ſome other eminent
on, we may diſcover, which moſt agreeth with the bodies
ly moveable, either the Earth, or the Sun and fixed Stars. But ſee
how Nature, in favour of our neceſſity and deſire, preſents us
with two eminent qualities, and no leſs different than motion and
reſt, and they are light and darkneſs, to wit, the being by nature
moſt bright, and the being obſcure, and wholly deprived of light:
the bodies therefore adorned with an internal and eternal
dour, are moſt different in eſſence from thoſe deprived of light:
The Earth is deprived of light, the Sun is moſt ſplendid in it ſelf,
and ſo are the fixed Stars. The ſix Planets do abſolutely
want light, as the Earth; therefore their eſſence agreeth with
the Earth, and differeth from the Sun and fixed Stars.
fore is the Earth moveable, immoveable the Sunne and Starry
Sphere.
From the Earths
obſcurity, and the
ſplendour of the
Sun, and fixed
Stars, is argued,
that it is
ble, and they
moveable.
SIMP. But the Authour will not grant, that the ſix Planets are
tenebroſe, and by that negative will he abide. Or he will argue
the great conformity of nature between the ſix Planets, and the
Sun, and Fixed Stars; and the diſparity between them and the
Earth from other conditions than from tenebroſity and light; yea,
now I remember in the fifth objection, which followeth, he layeth
down the vaſt difference between the Earth and the Cœleſtial

Bodies, in which he writeth, That the Copernican Hypotheſis
would make great confuſion and perturbation in the Syſteme of the
Vniverſe, and amongst its parts: As for inſtance, amongſt

bodies that are immutable and incorruptible, according to
tle, Tycho, and others; amongſt bodies, I ſay, of ſuch nobility, by
the confeſſion of every one, and Copernicus himſelf, who affirmeth
them to be ordinate, and diſpoſed in a perfect conſtitution, and
removeth from them all inconſtancy of vertue amongſt, theſe
dies, I ſay once more, ſo pure, that is to ſay, amongſt Venus, Mars,
&c. to place the very ſink of all corruptible matters, to wit, the
Earth, Water, Air, and all mixt bodies.
A fifih
ment againſt
pernicus.
Another
rence between the
Earth and the
leſtial bodies,
ken from purity &
impurity.
But how much properer a diſtribution, and more with nature,
yea with God himſelf, the Architect, is it, to ſequeſter the pure
1from the impure, the mortal from the immortal, as other Schools
teach; which tell us that theſe impure and frail matters are
teined within the anguſt concave of the Lunar Orb, above which
with uninterrupted Series the things Celeſtial diſtend themſelves.
SALV. It's true that the Copernican Syſteme introduceth

ſtraction in the univerſe of Aristotle; but we ſpeak of our own
Univerſe, that is true and real. Again if this Author will infer
the diſparity of eſſence between the Earth and Celeſtial bodies
from the incorruptibility of them, and the corruptibility of it in
the method of Ariſtotle, from which diſparity he concludeth
tion to belong to the Sun and fixed Stars, and the immobility of
the Earth, he will flatter himſelf with a Paralogiſme, ſuppoſing

that which is in queſtion; for Ariſtotle inferreth the
lity of Celeſtial bodies from motion, which is in diſpute,
ther it belongeth to them or to the Earth. Of the vanity of theſe
Rhetorical Illations enough hath been ſpoken. And what can be

more fond, than to ſay, that the Earth and Elements are
ſhed and ſequeſtred from the Celeſtial Spheres, and confined
within the Lunar Orb? Is, not then the Moons Orb one of the
Celeſtial Spheres, and according to conſent compriſed in the
middle of all the reſt? Its a new way to ſeparate the pure from
the impure, and the ſick from the ſound, to aſſigne the infected
quarters in the heart of the City: I had thought that the ^{*}

houſe ought to have been removed as far off as was poſſible.
Copernicus admireth the diſpoſition of the parts of the Univerſe,
for that God hath conſtituted the grand Lamp, which is to give
light all over his Temple in the centre of it, and not on one
ſide. And as to the Earths being betwixt Venus and Mars,
we will but hint the ſame; and do you, in favour of this Author,
trie to remove it thence. But let us not ^{*} mix theſe Rhetorical

Flowers with ſolid Demonſtrations, rather let us leave them to
the Orators, or if you will to the Poets, who know how in their
drolling way to exalt by their prayſes things moſt ſordid, yea and
ſometimes moſt pernicious. And if any thing elſe remain, let us
diſpatch it, as we have done the reſt.
Copernicus in
troduceth confuſion
in the Univerſe of
Ariſtotle.
The Paralogiſme
of the Author of
Anti-Tycho.
It ſeemeth a
folly to affirm the
Earth to be
out the Heavens.
* Lazeretto
* Intrecciare, to
twine flowers in a
garland.
SIMP. There is the ſixth and laſt argument, wherein he

keth it a very improbale thing. [That a corruptible and diſſipable
body ſhould move with a perpetual and regular motion; and this
he confirmeth with the example of living creatures, which moving
with a motion natural to them, yet grow weary, and have need of
repoſe to reſtore their ſtrength.] But what hath this motion to do
with that of the Earth, that in compariſon to theirs is immenſe?
Beſides, to make it move with three motions that run and draw
ſeveral wayes: Who would ever aſſert ſuch Paradoxes, unleſſe
he had ſworn to be their defender? Nor doth that avail in this
1caſe, which Copernicus alledgeth, that by reaſon this motion is
natural to the Earth and not violent, it worketh contrary effects
to violent motions; and that thoſe things diſſolve and cannot
long ſubſiſt, to which impulſe is conferred, but thoſe ſo made
by nature do continue in their perfect diſpoſure; this anſwer
ficeth not, I ſay, for it is overthrown by that of ours. For the
nimal is a natural body, and not made by art, and its motion is
natural, deriving it ſelf from the ſoul, that is, from an intrinſick
principle; and that motion is violent, whoſe beginning is
out, and on which the thing moved conferreth nothing;
ever, if the animal continueth its motion any long time, it grows
weary, and alſo dyeth, if it obſtinately ſtrive to perſiſt therein.
You ſee then that in nature we meet on all ſides with notions
trary to the Copernican Hypotheſis, and none in favour of it. And
for that I have nothing more wherein to take the part of this
ponent, hear what he produceth againſt Keplerus (with whom
he diſputeth) upon that argument, which the ſaid Kepler bringeth
againſt thoſe who think it an inconvenient, nay impoſſible thing,
to augment the Starry Sphere immenſely, as the Copernican
potheſis requireth. Kepler therefore inſtanceth, ſaying:
us ect, accidens præter modulum ſubjecti intendere, quàm ſub-

jectum ſine accidente augere. Copernicus ergo veriſimilius facit,
qui auget Orbem Stellarum fixarum abſque motu, quam Ptolomæus,
qui auget motum fixarum immenſà velocitate. [Which makes this
Engliſh.] Its harder to ſtretch the accident beyond the model of the
ſubject than to augment the ſubject without the accident. Coperni-
hath more probability on his ſide, who encreaſeth the Orb of the
fixed Stars without motion, than Ptolomy who augmenteth the
motion of the fixed Stars to an immenſe degree of velocity.

Which objection the Author anſwereth, wondering how much
Kepler deceived himſelf, in ſaying, that in the Ptolomaick
ſis the motion encreaſeth beyond the model of the ſubject, for in
his judgment it doth not encreaſe, ſave onely in conformity to the
model, and that according to its encreaſement, the velocity of

the motion is augmented. Which he proveth by ſuppoſing a
chine to be framed, that maketh one revolution in twenty four
hours, which motion ſhall be called moſt ſlow; afterwards
poſing its ſemidiameter to be prolonged, as far as to the diſtance
of the Sun, its extreme will equal the velocity of the Sun; and
it being cantinued out unto the Starry Sphere, it will equal the
velocity of the fixed Stars, though in the circumferrnce of the
machine it be very ſlow. Now applying this conſideration of the
machine to the Starry Sphere, let us imagine any point in its
midiameter, as neer to the centre as is the ſemidiameter of the
chine; the ſame motion that in the Starry Sphere is exceeding
1ſwift, ſhall in that point be exceeding ſlow; But the great
nitude of the body is that which maketh it of exceeding ſlow, to
become exceeding ſwift, although it continueth ſtill the ſame, and
thus the velocity encreaſeth, not beyond the model of the
ject, but rather according to it, and to its magnitude; very
ferently from the imagination of Kepler.
A ſixth
ment againſt
pernicus, taken
from animals, who
have need of
though their
on be natural.
An argument
from Kepler in
vour of
cus.
The Author of
the Anti Tycho
poſeth Kepler.
The velocity of
the circular
on increaſeth,
cording to the
creaſe of the
meter of the circle.
SALV. I do not believe that this Author hath entertained ſo
mean and poor a conceit of Kepler, as to perſwade himſelf that
he did not underſtand, that the higheſt term of a line drawn from
the centre unro the Starry Sphere, moveth more ſwiftly than a
point of the ſame line taken within a yard or two of the centre. And
therefore of neceſſity he muſt have conceived and

ed that the mind and intention of Kepler was to have ſaid, that
it is leſſe inconvenient to encreaſe an immoveable body to an
traordinary magnitude, than to aſcribe an extraordinary velocity
to a body, though very bigge, having regard to the model,
that is to the gauge, and to the example of other natural bodies;
in which we ſee, that the diſtance from the centre encreaſing, the
velocity diminiſheth; that is, that the periods of their
ons take up longer times. But in reſt which is not capable of

mentation or diminution, the grandure or ſmalneſſe of the body
maketh no differeuce. So that if the anſwer of the Author would
be directed againſt the argument of Kepler, it is neceſſary, that
that Author doth hold, that to the movent principle its one and the
ſame to move in the ſame time a body very ſmall, or very
menſe, in regard that the augmentation of velocity inſeparably
attends the augmentation of the maſſe. But this again is contrary

to the Architectonical rule of nature, which doth in the leſſer
Spheres, as we ſee in the Planets, and moſt ſenſibly in the
cean Stars, obſerve to make the leſſer Orbs to circulate in ſhorter
times: Whence the time of Saturns revolution is longer than all
the times of the other leſſer Spheres, it being thirty years; now
the paſſing from this to a Sphere very much bigger, and to make
it move in 24. hours, may very well be ſaid to exceed the rules of
the model. So that if we would but attentively conſider it, the
Authors anſwer oppoſeth not the intent and ſenſe of the argument,
but the expreſſing and manner of delivering of it; where again
the Author is injurious, and cannot deny but that he artificially
diſſembled his underſtanding of the words, that he might charge
Kepler with groſſe ignorance; but the impoſture was ſo very dull
and obvions, that he could not with all his craft alter the
on which Kepler hath begot of his Doctrine in the minds of all
the Learned. As in the next place, to the inſtance againſt the
perpetual motion of the Earth, taken from the impoſſibility of
its moving long without wearineſſe, in regard that living
1tures themſelves, which yet move naturally, and from an intern
principle, do grow weary, and have need of reſt to relax and
freſh their members --------
An explanation
of the true ſenſe of
Kepler and his
fence.
The greatneſſe
and ſmalneſſe of
the body make a
difference in
on and not in reſt.
The order of
ture is to make the
leſſer Orbs to
culate in ſhorter
times, and the
ger in longer times.
SAGR. Methinks I hear Kepler anſwer him to that, that
there are ſome kinde of animals which refreſh themſelves after
wearineſſe, by rowling on the Earth; and that therefore there

is no need to fear that the Terreſtrial Globe ſhould tire, nay it
may be reaſonably affirmed, that it enjoyeth a perpetual & moſt
tranquil repoſe, keeping it ſelf in an eternal rowling.
The feigned
ſwer of Kepler
vered with an
tificial Irony.
SALV. You are too tart and Satyrical, Sagredus: but let us
lay aſide jeſts, whilſt we are treating of ſerious things.
SAGR. Excuſe me, Salviatus, this that I ſay is not ſo
lutely beſides the buſineſs, as you perhaps make it; for a motion
that ſerveth inſtead of reſt, and removeth wearineſs from a body
tired with travail, may much more eaſily ſerve to prevent the

ming of that wearineſs, like as preventive remedies are more eaſie
than curative. And I hold for certain, that if the motion of
mals ſhould proceed in the ſame manner as this that is aſcribed to
the Earth, they would never grow weary; Seeing that the
neſs of the living creature, deriveth it ſelf, in my opinion, from

the imployment of but one part alone in the moving of its ſelf,
and all the reſt of the body; as v. g. in walking, the thighs and
the legs onely are imployed for carrying themſelves and all the
reſt: on the contrary, you ſee the motion of the heart to be as it
were indefatigable, becauſe it moveth it ſelf alone. Beſides, I

know not how true it may be, that the motion of the animal is
tural, and not rather violent: nay, I believe that one may truly
ſay, that the ſoul naturally moveth the members of an animal with
a motion preternatural, for if the motion upwards is
ral to grave bodies, the lifting up of the legs, and the thighs,
which are grave bodies, in walking, cannot be done without
lence, and therefore not without labour to the mover. The
climbing upwards by a ladder carrieth the grave body contrary to
its natural inclination upwards, from whence followeth wearineſs,
by reaſon of the bodies natural averſneſs to that motion: but in
moving a moveable with a motion, to which it hath no averſion,

what laſſitude, what diminution of vertue and ſtrength need we
fear in the mover? and how ſhould the forces waſte, where they
are not at all imployed?
Animals would
not grow weary of
their motion,
ceeding as that
which is aſſigned
to the terreſtrial
Globe.
The cauſe of the
wearineſſe of
mals.
The motion of
an animal is rather
to be called violent
than natural.
The ſtrength
miniſheth not,
where it is not
ployed.
SIMP. They are the contrary motions wherewith the Earth is
pretended to move, againſt which the Authour produceth his
gument.
SAGR. It hath been ſaid already, that they are no wiſe
traries, and that herein the Authour is extteamly deceived, ſo
that the whole ſtrength of the argument recoileth upon the
1ponent himſelf, whilſt he will make the Firſt Mover to hurry

along with it all the inferiour Spheres, contrary to the motion
which they themſelves at the ſame time exerciſe. It belongs
fore to the Primum Mobile to grow weary, which beſides the
moving of its ſelf is made to carry ſo many other Spheres, and
which alſo ſtrive againſt it with a contrary motion. So that
the ultimate concluſion that the Authour inferred, ſaying, that
diſcourſing of the effects of Nature, a man alwayes meets with
things that favour the opinion of Ariſtoile and Ptolomy, and
ver any one that doth not interfer with Copernicus, ſtands in need
of great conſideration; and it is better to ſay, that one of theſe
two Hypotheſes being true, and the other neceſſarily falſe, it is
impoſſible that a man ſhould ever be able to finde any
ment, experience, or right reaſon, in favour of that which is

falſe, like as to the truth none of theſe things can be repugnant.
Vaſt difference, therefore, muſt needs be found between the
ſons and arguments produced by the one and other party, for and
againſt theſe two opinions, the force of which I leave you your
ſelf to judge of, Simplicius.
The argument
of Claramontius
recoileth upon
ſelf.
True
ons meet with
ny concluſive
guments, ſo do not
the falſe.
SALV. But you, Sagredus, being tranſported by the velocity
of your wit, have taken my words out of my mouth, whilſt I was
about to ſay ſomething, touching this laſt argument of the Author;
and although you have more then ſufficiently refuted him, yet
nevertheleſſe I will adde ſomewhat, which then ran in my minde.
He propoſeth it as a thing very unlikely, that a body diſſipable
and corruptible, as the Earth, ſhould perpetually move with a
gular motion, cſpecially for that we ſee living creatures in the end
to grow weary, and to ſtand in need of reſt: and the improbability
is increaſed, in that the ſaid motion is required to be of velocity
incomparable and immenſe, in reſpect to that of animals. Now, I
cannot ſee why the velocity of the Earth ſhould, at preſent,
ble it; ſo long as that of the ſtarry Sphere ſo very much bigger
doth not occaſion in it any diſturbance more conſiderable, than that
which the velocity of a machine, that in 24 hours maketh but one
ſole revolution, produceth in the ſame. If the being of the
city of the Earths converſion, according to the model of that
chine, inferreth things of no greater moment than that, let the
thor ceaſe to fear the Earths growing weary; for that not one of
the moſt feeble and ſlow-pac't animals, no not a Chamæleon would

tire in moving no more than ^{*} four or five yards in 24 hours; but
if he pleaſe to conſider the velocity to be no longer, in relation to

the model of the machine, but abſolutely, and inaſmuch as the
moveable in 24 hours is to paſs a very great ſpace, he ought to ſhew
himſelf ſo much more reſerved in granting it to the ſtarry Sphere,
which with a velocity incomparably greater than that of the
1Earth is to carry along with it a thouſand bodies, each much
ger than the Terreſtrial Globe.
* Cinque ò ſei
braccia Fiorentini.
Wearineß more
to be feared in the
ſtarry Sphere than
in the terreſtriall
Globe.
Here it remains for us to ſee the proofs, whereby the Authour
concludes the new ſtars Anno 1572. and Anno 1604. to be
nary, and not cœleſtial, as the Astronomers of thoſe times were
generally perſwaded; an enterprize very great certainly; but I
have conſidered, that it will be better, in regard the Book is new
and long, by reaſon of its many calculations, that between this
vening and to morrow morning I make them as plain as I can, and
ſo meeting you again to morrow to continue our wonted
rences, give you a brief of what I ſhall obſerve therein; and if we
have time left, we will ſay ſomething of the Annual motion
bed to the Earth. In the mean time, if either of you, and
cius in particular, hath any thing to ſay more, touching what relates
to the Diurnal motion, at large examined by me, we have a little
time ſtill left to treat thereof.
SIMP. I have no more to ſay, unleſſe it be this, that the
ſes that this day have falne under our debate, have appeared to me
fraught with very acute and ingenious notions, alledged on
nicus his ſide, in confirmation of the motion of the Earth, but yet
I find not my ſelf perſwaded to believe it; for in ſhort, the things
that have been ſaid conclude no more but this, that the reaſons
for the ſtability of the Earth are not neceſſary; but all the while
no demonſtration hath been produced on the other ſide, that doth
neceſſarily convince and prove its mobility.
SALV. I never undertook, Simplicius, to remove you from that
your opinion; much leſs dare I preſume to determine definitively
in this controverſie: it onely was, and ſtill ſhall be in the enſuing
diſputations my intent, to make it appear to you, that thoſe who
have thought that moſt ſwift motion of 24 hours doth belong to
the Earth alone, and not to the Univerſe, the Earth onely
ded, were not induced to believe, that ſo it might and ought to do
out of any blind perſwaſion; but that they did very well ſee, try,
and examine the reaſons on the contrary ſide, and alſo not
ly anſwer them. With the ſame intention, if it ſtand with your
liking, and that of Sagredus, we may paſſe to the conſideration of
that other motion; firſt, by Aristarchus Samius, and afterwards
by Nicholaus Copernicus aſcribed to the ſaid Terreſtrial Globe,
which is, as, I believe, you have heretofore heard, made under the
Zodiack within the ſpace of a year about the Sun, immoveably
placed in the centre of the ſaid Zodiack.
SIMP. The diſquiſition is ſo great, and ſo noble, that I ſhall
gladly hearken to the diſcuſſion thereof, perſwading my ſelf that I
ſhall hear what ever can be ſaid of that matter. And I will
1wards by my ſelf, according to my uſual cuſtome, make more
liberate reflexions upon what hath been, and is to be ſpoken; and
if I ſhould gain no more but this, it will be no ſmall benefit
that I ſhall be able to diſcourſe more Logically.
SAGR. Therefore, that we may no further weary Salviatus,
we will put a period to the diſputations of this day, and
aſſume our conference to morrow in the uſual manner, with hope
to hear very pleaſing novelties.
SIMP. I will leave with you the Book De ſtellis novis, and
ry back this of the Concluſions, to ſee what is written therein
gainſt the Annual motion, which are to be the arguments of our
diſcourſe to morrow.
1
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19[Figure 9]10[Figure 10]11[Figure 11]12[Figure 12]13[Figure 13]14[Figure 14]15[Figure 15]16[Figure 16]17[Figure 17]
Place this Plate
at the end of
the Second
Dialogue.
1
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1
GALILÆUS
Galilæus Lyncæus,
HIS
SYSTEME
OF THE
WORLD.
The Third Dialogue.
INTERLOCVTORS.
SALVIATUS, SAGREDUS, and SIMPLICIUS.
SAGR. The great deſire wherewith I have expected
your coming, that I might hear the novel
conceits touching the annual
on of this our Globe, hath made me
think the houres of the laſt night, and
thoſe of this morning very tedious,
though I ſpent them not idly, but lying
awake I imployed a good part thereof in
ruminating upon our yeſterdayes
ſes, weighing the reaſons alledged by both parties, in favour of
the two contrary Hypotheſes, that of Ariſtotle and Ptolomy, and
this of Ariſtarchus, and Copernicus. And really methinks, that
which ever of theſe parties have been deceived, they are worthy of
excuſe, ſo ſpecious and valid in appearance are the reaſons that
may have perſwaded them either way; though nevertheleſſe we
1do for the moſt part cloſe with thoſe produced by the grave
thours firſt above mentioned. But albeit that the Peripatetick
potheſis, by reaſon of its antiquity, hath had many followers and
fautors, and the other very few; firſt, for its obſcurity, and next,
for its novelty, yet methinks I diſcover amongſt thoſe many,
and particularly amongſt the modernes ſome, who for the
port of the opinion by them eſteemed true, have introduced
other reaſons ſufficiently childiſh, I could ſay ridiculous.
SALV. I have met with the like, and ſo much worſe than

yours, that I bluſh to rehearſe them, not ſo much to ſpare the fame
of their Authours, the names of whom might be perpetually
cealed, as becauſe I am aſhamed ſo much to ſtain the honour of
mankinde. In obſerving of theſe men, I have found that ſome
there are who prepoſterouſly reaſoning, firſt ſtabliſh the
ſion in their fancy, and (either becauſe it is their own, or elſe
longs to a perſon whom they much confide in) ſo firmly imprint
it in their opinions, that it is altogether impoſſible ever wholly to
efface it: and thoſe reaſons which they themſelves ſtumble upon,
or which they hear others to alledge in confirmation of the
ceit entertained, though never ſo ſimple and inſipid, inſtantly find
credit and applauſe with them: but on the contrary, thoſe which
are brought againſt their opinion, though ingenuous and
ding, they receive not only with nauſeating, but with diſdain and
bitter indignation, yea, you ſhall have one of theſe ſo inraged, as
that he will not be backward to try all wayes to ſuppreſs and ſilence
their adverſaries: and of this I my ſelf have had ſome experience.
Some in arguing
firſt fix in their
minds the
ſion beleeved by
them, and then
dapt their reaſons
to that.
SAGR. Indeed theſe men deduce not the concluſion from the
premiſes, nor confirme them with reaſons, but accomodate, or to
ſay better, diſcommodate and diſtort the premiſes and arguments
to make them ſpeak in favour of their pre-aſſumed and
ous concluſions. It is not good therefore to contract familiarity
with theſe men; and the rather, for that their converſation is not
only unpleaſant, but alſo dangerous. Yet let us continue our
ference with Simplicius however, whom I have known this long
while for a man of great ingenuity, and altogether void of malice:
beſides he is well verſt in the Peripatetick Doctrine; ſo that I may
aſſure my ſelf, that what ſhall not fall within the reach of his
ſon for the ſupport of the Ariſtotelian Hypotheſis, will not eaſily
be found out by others. But ſee yonder he comes, quite out of
winde, whoſe company we have ſo long deſired: we were juſt now
ſpeaking againſt the ſmall haſt you made to come to us.
SIMP. You muſt not blame me, but Neptune, for this my long
ſtay; which in the ebbe of this mornings tide hath in a manner
drain'd away the waters, for the Gondola that brought me, being
entered not far from hence into a certain Channel, wanting depth,
1where I was ſtranded, and forced to ſtay there more than a full
hour, in expecting the return of the tide: and there waiting in
this manner, without being able to get out of the boat, which on a
ſudden ran a ground, I obſerved a certain accident, which to me

ſeemed very ſtrange; and it was this, that in the waters ebbing
I ſaw it retreat very faſt by ſeveral ſmall rivolets, the ouze being
in many places diſcovered, and whilſt I ſtood looking upon this
fect, I ſaw this motion in an inſtant to ceaſe, and without a
nutes interval the ſame water to begin to return back again, and
the tide from ebbing to become young flood, without ſtanding
ſtill a moment: an effect that as long as I have dwelt in Venice,
I never took notice of before.
The motion of
the water in ebbing
and flowing not
terrupted by reſt.
SAGR. It is very much, that you ſhould be left thus on ground,
amongſt ſmall Channels; in which rivolets, as having very little
declivity, the riſing or falling of the main ſea, the thickneſs onely
of a paper is ſufficient to make the water to ebbe and flow for good
long ſpaces of time: like as in ſome creeks of the Sea, its flowing
four or ſix ^{*} yards onely, maketh the water to overflow the
cent Marſhes for ſome hundreds and thouſands of ^{*}
* Pertiche
tiani.
SIMP. This I know very well, but I ſhould have thought, that
between the ultimate terme of ebbing, and the firſt beginnng to
flow, there ſhould have interpoſed ſome conſiderable interval of
reſt.
SAGR. This will appear unto you, if you caſt your eye upon
the bank or piles, where theſe mutations are made
ly, but not that there is any real time of ceſſation.
SIMP. I did think, that becauſe theſe two motions were
trary, there ought to be in the midſt between them ſome kind of
reſt; conformable to the Doctrine of Ariſtotle, which demonſtrates.
that in puncto regreſſus mediat quies.
SAGR. I very well remember this place: but I bear in minde
alſo, that when I read Philoſophy, I was not thorowly ſatisfied
with Ariſtotles demonſtration; but that I had many experiments
on the contrary, which I could ſtill rehearſe unto you, but I am
unwilling to ſally out into any other digreſſions, we being met
here to diſcourſe of the propoſed mattes, if it be poſſible, without
theſe excurſions wherewith we have interrupted our diſputes in
thoſe dayes that are paſt.
SIMP. And yet we may with convenience, if not interrupt
them, at leaſt prolong them very much, for returning
day home, I ſet my ſelſ to read the Tractate of Concluſions, where
I find Demonſtrations againſt this annual motion aſcribed to the
Earth, very ſolid; and becauſe I would not truſt my memory with
the punctual relation of them, I have brought back the Book
long with me.
1
SAGR. You have done very well; but if we would re-aſſume
our Diſputations according to yeſterdayes appointment, it is
quiſite that we firſt hear what account Salviatus hath to give us
of the Book, De ſtellis novis, and then without interruption we
may proceed to the Annual motion. Now what ſay you,
tus touching thoſe ſtars? Are they really pull'd down from
ven to theſe lower regions, by vertue of that Authours
ons, whom Simplicius mentioneth?
SALV. I ſet my ſelf laſt night to peruſe his proceedings, and I
have this morning had another view of him, to ſee whether that
which he ſeemed over night to affirm, were really his ſenſe, or my
dreams and phantaſtical nocturnal imaginations; and in the cloſe
found to my great grief that thoſe things were really written and
printed, which for the reputation-ſake of this Philoſopher I was
unwilling to believe. It is in my judgment impoſſible, but that he
ſhould perceive the vanity of his undertaking, aſwell becauſe it is
too apert, as becauſe I remember, that I have heard him
ned with applauſe by the Academick our Friend: it ſeemeth to
me alſo to be a thing very unlikely, that in complacency to others,
he ſhould be induced to ſet ſo low a value upon his reputation, as
to give conſent to the publication of a work, for which he could
expect no other than the cenſure of the Learned.
SAGR. Yea, but you know, that thoſe will be much fewer
than one for an hundred, compared to thoſe that ſhall celebrate
and extoll him above the greateſt wits that are, or ever have been
in the world: He is one that hath mentioned the
tick inalterability of Heaven againſt a troop of Aſtronomers, and
that to their greater diſgrace hath foiled them at their own
pons; and what do you think four or five in a Countrey that
cern his triflings, can do againſt the innumerable multitude, that,
not being able to diſcover or comprehend them, ſuffer themſelves
to be taken with words, and ſo much more applaud him, by how
much the leſſe they underſtand him? You may adde alſo, that
thoſe few who underſtand, ſcorn to give an anſwer to papers ſo
trivial and unconcludent; and that upon very good reaſons,
cauſe to the intelligent there is no need thereof, and to thoſe that
do not underſtand, it is but labour loſt.
SALV. The moſt deſerved puniſhment of their demerits would
certainly be ſilence, if there were not other reaſons, for which it
is haply no leſſe than neceſſary to reſent their timerity: one of
which is, that we Italians thereby incur the cenſure of Illiterates,
and attract the laughter of Forreigners; and eſpecially to ſuch
who are ſeparated from our Religion; and I could ſhew you
ny of thoſe of no ſmall eminency, who ſcoff at our Academick,
and the many Mathematicians that are in Italie, for ſuffering the
1follies of ſuch a ^{*} Fabler againſt Aſtronomers to come into the

light, and to be openly maintained without contradiction; but
this alſo might be diſpenſed with, in reſpect of the other greater
occaſions of laughter, wherewith we may confront them
ing on the diſſimulation of the intelligent, touching the follies of
theſe opponents of the Doctrines that they well enough
ſtand.
* Lorenzini.
SAGR. I deſire not a greater proof of thoſe mens petulancy,
and the infelicity of a Copernican, ſubject to be oppoſed by ſuch
as underſtand not ſo much as the very firſt poſitions, upon which
he undertakes the quarrel.
SALV. You will be no leſſe aſtoniſhed at their method in
futing the Astronomers, who affirm the new Stars to be ſuperiour
to the Orbs of the Planets; and peradventure in the ^{†} Firmament

it ſelf.
† He taketh the
Firmament for the
Starry Sphere, and
as we vulgarly
ceive the word.
SAGR. But how could you in ſo ſhort a time examine all this
Book, which is ſo great a Volume, and muſt needs contain very
many demonſtrations.?
SALV. I have confined my ſelf to theſe his firſt confutations, in
which with twelve demonſtrations founded upon the obſervations
of twelve Aſtronomers, (who all held, that the Star, Anno 1572.
which appeared in Caſſiopeia, was in the Firmament) he proveth it
on the contrary, to be beneath the Moon, conferring, two by two,
the meridian altitudes, proceeding in the method that you ſhall
underſtand by and by. And becauſe, I think, that in the
nation of this his firſt progreſſion, I have diſcovered in this
thour a great unlikelihood of his ability to conclude any thing
gainſt the Aſtronomers, in favour of the Peripatetick Philoſophers,
and that their opinion is more and more concludently confirmed,
I could not apply my ſelf with the like patience in examining his
other methods, but have given a very ſlight glance upon them,
and am certain, that the defect that is in theſe firſt impugnations,
is likewiſe in the reſt. And as you ſhall ſee, by experience, very
few words will ſuffice to confute this whole Book, though
led with ſo great a number of laborious calculations, as here you

ſee. Therefore obſerve my proceedings. This Authour
taketh, as I ſay, to wound his adverſaries with their own weapons,
i.e. a great number of obſervations made by themſelves, to wit, by
twelve or thirteen Authours in number, and upon part of them he
makes his ſupputations, and concludeth thoſe ſtars to have been
below the Moon. Now becauſe the proceeding by
ries very much pleaſeth me, in regard the Authour himſelf is not
here, let Simplicius anſwer me to the queſtions that I ſhall ask
him, as he thinks he himſelf would, if he were preſent. And
ſuppoſing that we ſpeak of the foreſaid Star, of Anno 1572.
1pearing in Caſſiopeia, tell me, Simplicius, whether you believe that
it might be in the ſame time placed in divers places, that is,
mongſt the Elements, aud alſo amongſt the planetary Orbs, and
alſo above theſe amongſt the fixed Stars, and yet again infinitely
more high.
The method
ſerved by Clar. in
confuting the
ſtronomers, and by
Salviatus in
ting him.
SIMP. There is no doubt, but that it ought to be confeſſed
that it is but in one only place, and at one ſole and determinate
diſtance from the Earth.
SALV. Therefore if the obſervations made by the
mers were exact, and the calculations made by this Author were
not erroneous, it were eaſie from all thoſe and all theſe to
collect the ſame diſtances alwayes to an hair, is not this true?
SIMP. My reaſon hitherto tells me that ſo it muſt needs be;
nor do I believe that the Author would contradict it
SALV. But when of many and many computations that have
been made, there ſhould not be ſo much as two onely that prove
true, what would you think of them?
SIMP. I would think that they were all falſe, either through
the fault of the computiſt, or through the defect of the
vators, and at the moſt that could be ſaid, I would ſay, that but
onely one of them and no more was true; but as yet I know not
which to chooſe.
SALV. Would you then from falſe fundamentals deduce and
eſtabliſh a doubtful concluſion for ttue? Certainly no. Now the
calculations of this Author are ſuch, that no one of them agrees
with another, you may ſee then what credit is to be given to
them.
SIMP. Indeed, if it be ſo, this is a notable failing.
SAGR. But by the way I have a mind to help Simplicius, and
the Author by telling Salviatus, that his arguments would hold
good if the Author had undertook to go about to find out
ly the diſtance of the Star from the Earth, which I do not think
to be his intention; but onely to demonſtrate that from thoſe
obſervations he collected that the Star was ſublunary. So
that if from thoſe obſervations, and from all the computations
made thereon, the height of the Star be alwayes collected to be
leſſe than that of the Moon, it ſerves the Authors turn to
vince all thoſe Aſtronomers of moſt impardonable ignorance,
that through the defect either of Geometry or Arithmetick, have
not known how to draw true concluſions from their own
tions themſelves.
SALV. It will be convenient therefore that I turn my ſelf to
you, Sagredus, who ſo cunningly aphold the Doctrine of this
Author. And to ſee whether I can make Simplicius, though not
very expert in calcnlations, and demonſtrations to apprehend the
1inconcluſiveneſſe at leaſt of the demonſtrations of this Author,
firſt propoſed to conſideration, and how both he, and all the
Aſtronomers with whom he contendeth, do agree that the new
Star had not any motion of its own, and onely went round with
the diurnal motion of the primum mobile; but diſſent about the
placing of it, the one party putting it in the Celeſtial Region,
that is above the Moon, and haply above the fixed Stars, and
the other judging it to be neer to the Earth, that is, under the
concave of the Lunar Orb. And becauſe the ſituation of the new
ſtar, of which we ſpeak, was towards the North, and at no very
great diſtance from the Pole, ſo that to us Septentrionals, it did
never ſet, it was an eaſie matter with Aſtronomical inſtruments
to have taken its ſeveral meridian altitudes, as well its ſmalleſt
under the Pole, as its greateſt above the ſame; from the
ring of which altitudes, made in ſeveral places of the Earth,
ſituate at different diſtances from the North, that is, different
from one another in relation to polar altitudes, the ſtars diſtance
might be inferred: For if it was in the Firmament amongſt the

other fixed ſtars, its meridian altitudes taken in divers elevations
of the pole, ought neceſſarily to differ from each other with the
ſame variations that are found amongſt thoſe elevations
ſelves; that is, for example, if the elevation of the ſtar above
the horizon was 30 degrees, taken in the place where the polar
altitude was v. gr. 45 degrees, the elevation of the ſame ſtar
ought to have been encreaſed 4 or 5 degrees in thoſe more
thernly places where the pole was higher by the ſaid 4 or 5
grees. But if the ſtars diſtance from the Earth was but very little,
in compariſon of that of the Firmament; its meridian altitudes
ought approaching to the North to encreaſe conſiderably more
than the polar altitudes; and by that greater encreaſe, that is,
by the exceſſe of the encreaſe of the ſtars elevation, above the
encreaſe of the polar elevation (which is called the difference of
Parallaxes) is readily calculated with a cleer and ſure method,
the ſtars diſtance from the centre of the Earth. Now this Author
taketh the obſervations made by thirteen Aſtronomers in ſundry
elevations of the pole, and conferring a part of them at his
ſure, he computeth by twelve collations the new ſtars height to
have been alwayes beneath the Moon; but this he adventures to
do in hopes to find ſo groſſe ignorance in all thoſe, into whoſe
hands his book might come, that to ſpeak the truth, it hath turn'd
my ſtomack; and I wait to ſee how thoſe other Aſtronomers, and
particularly Kepler, againſt whom this Author principally
veigheth, can contein themſelves in ſilence, for he doth not uſe
to hold his tongue on ſuch occaſions; unleſſe he did poſſibly
think the enterprize too much below him. Now to give you to
1underſtand the ſame, I have upon this paper tranſcribed the
cluſions that he inferreth from his twelve indagations; the firſt of
which is upon the two
The greateſt and
leaſt elevations of
the new ſtar differ
not from each
ther more than the
polar allitudes, the
ſaid ſtar being in
the Firmnment.
Of Maurolicus and Hainzelius, from which the Star is collected to have been diſtant from the centre leſſe than 3 ſemidiameters of the Earth, the difference of Parallaxes being 4 gr. 42 m.30 ſec.3 ſemid.2. And is calculated on the obſervations of Hain-zelius, with Parall. of 8. m. 30 ſec. and its di-ſtance from the centre is computed to be more than25 ſemid.3. And upon the obſervations of Tycho and Hain-zelius, with Parall. of 10 m. and the diſtance of the centre is collected to be little leſſe than19 ſemid.4. And upon the obſervations of Tycho and the Landgrave, with Parall. of 14 m. the diſtance from the centre is made to be about10 ſemid.5. And upon the obſervations of Hainzelius and Gemma, with Parall. of 42 m. 30 ſec. whereby the diſtance is gathered to be about4 ſemid.6. And upon the obſervations of the Landgraveand Camerarius, with Parall. of 8 m. the di-ſtance is concluded to be about4 ſemid.7. And upon the obſervations of Tycho and Hage-cius, with Parall. of 6 m. and the diſtance is made31 ſemid.8. And upon the obſervations of Hagecius and Vr-ſinus with Parall. of 43 m. and the ſtars diſtance from the ſuperficies of the Earth is rendred1/2 ſemid.9. And upon the obſervations of Landgravius and Buſchius, with Parall. of 15 m. and the di-ſtance from the ſuperficies of the Earth is by ſupputation1/48 ſemid.10. And upon the obſervations of Maurolice and Munocius, with Parall. of 4 m. 30 ſec. and the compnted diſtance from the Earths ſurface is1/5 ſemid.11. And upon the obſervations of Munocius and Gemma, with Parall. of 55 m. and the diſtance from the centre is rendred13 ſemid.
112. And upon the obſervations of Munoſius and Vrſinus with Parall. of 1 gr. 36 m. and the di-ſtance from the centre cometh forth leſſe than7 ſemid.
Theſe are twelve indagations made by the Author at his
on, amongſt many which, as he ſaith, might be made by
ning the obſervations of theſe thirteen obſervators. The which
twelve we may believe to be the moſt favourable to prove his
intention.
SAGR. I would know whether amongſt the ſo many other
dagations pretermitted by the Author, there were not ſome that
made againſt him, that is, from which calculating one might find
the new ſtar to have been above the Moon, as at the very firſt
ſight I think we may reaſonably queſtion; in regard I ſee theſe
already produced to be ſo different from one another, that ſome
of them give me the diſtance of the ſaid ſtar from the Earth, 4, 6,
10, 100, a thouſand, and an hundred thouſand times bigger one
than another; ſo that I may well ſuſpect that amongſt thoſe that
he did not calculate, there was ſome one in fauour of the adverſe
party. And I gueſſe this to be the more probable, for that I
not conceive that thoſe Aſtronomers the obſervators could want
the knowledg and practice of theſe computations, which I think
do not depend upon the abſtruceſt things in the World. And
deed it will ſeem to me a thing more than miraculous, if whilſt in
theſe twelve inveſtigations onely, there are ſome that make the
ſtar to be diſtant from the Earth but a few miles, and others that
make it to be but a very fmall matter below the Moon, there are
none to be found that in favour of the contrary part do make it
ſo much as twenty yards above the Lunar Orb. And that which
ſhall be yet again more extravagant, that all thoſe Aſtronomers
ſhould have been ſo blind as not to have diſcovered that their ſo
apparent miſtake.
SALV. Begin now to prepare your ears to hear with infinite
admiration to what exceſſes of confidence of ones own authority
and others folly, the deſire of contradicting and ſhewing ones
ſelf wiſer than others, tranſports a man. Amongſt the
tions omitted by the Author, there are ſuch to be found as make
the new ſtar not onely above the Moon, but above the fixed
ſtars alſo. And theſe are not a few, but the greater part, as you
ſhall ſee in this other paper, where I have ſet them down.
SAGR. But what ſaith the Author to theſe? It may be he did
not think of them?
SALV. He hath thought of them but too much: but ſaith, that
the obſervations upon which the calculations make the ſtar to be
infinitely remote, are erroneous, and that they cannot be
bined to one another.
1
SIMP. But this ſeemeth to me a very lame evaſion; for the
verſe party may with as much reaſon reply, that thoſe are
ous wherewith he collecteth the ſtar to have been in the
tary Region.
SALV. Oh Simplicius, if I could but make you comprehend
the craft, though no great craftineſſe of this Author, I ſhould
make you to wonder, and alſo to be angry to ſee how that he
palliating his ſagacity with the vail of the ſimplicity of your ſelf;
and the reſt of meer Philoſophers, would inſinuate himſelf into
your good opinion, by tickling your cars, and ſwelling your
bition, pretending to have convinced and ſilenced theſe petty
Aſtronomers, who went about to aſſault the impregnable
rability of the Peripatetick Heaven, and which is more, to have
foild and conquered them with their own arms. I will try with all
my ability to do the ſame; and in the mean time let Sagredus
take it in good part, if Simplicius and I try his patience, perhaps
a little too much, whilſt that with a ſuperfluous circumlocution
(ſuperfluous I ſay to his moſt nimble apprehenſion) I go about to
make out a thing, which it is not convenient ſhould be hid and
unknown unto him.
SAGR. I ſhall not onely without wearineſſe, but alſo with
much delight hearken to your diſcourſes; and ſo ought all
tetick Philoſophers, to the end they may know how much they
are oblieged to this their Protector.
SALV. Tell me, Simplicius, whether you do well comprehend,
how, the new ſtar being placed in the meridian circle yonder
wards the North, the ſame to one that from the South ſhould
go towards the North, would ſeem to riſe higher and higher
bove the Horizon, as much as the Pole, although it ſhould have
been ſcituate amongſt the fixed ſtars; but, that in caſe it were
conſiderably lower, that is nearer to the Earth, it would appear
to aſcend more than the ſaid pole, and ſtill more by how much
its vicinity was greater?
SIMP. I think that I do very well conceive the ſame; in
ken whereof I will try if I can make a mathematical Scheme of
it, and in this great circle [in Fig. 1. of this Dialogue.] I will
marke the pole P; and in theſe two lower circles I will note two
ſtars beheld from one place on the Earth, which let be A; and
let the two ſtars be theſe B and C, beheld in the ſame line A B C,
which line I prolong till it meet with a fixed ſtar in D. And then
walking along the Earth, till I come to the term E, the two
ſtars will appear to me ſeparated from the fixed ſtar D, and
vanced neerer to the pole P, and the lower ſtar B more, which
will appear to me in G, and the ſtar C leſſe, which will ap
pear to me in F, but the fixed ſtar D will have kept the ſame
diſtance from the Pole.
1
SALV. I ſee that you underſtand the buſineſſe very well. I
lieve that you do likewiſe comprehend, that, in regard the ſtar B
is lower than C, the angle which is made by the rayes of the
ſight, which departing from the two places A and E, meet in C,
to wit, this angle A C E, is more narrow, or if we will ſay more
acute than the angle conſtituted in B, by the rayes A B and
E B.
SIMP. This I likewiſe underſtand very well.
SALV. And alſo, the Earth beine very little and almoſt
ſible, in reſpect of the Firmament (or Starry Sphere;) and
ſequently the ſpace A E, paced on the Earth, being very ſmall in
compariſon of the immenſe length of the lines E G and E F,
ſing from the Earth unto the Firmament, you thereby collect that
the ſtar C might riſe and aſcend ſo much and ſo much above the
Earth, that the angle therein made by the rayes which depart
from the ſaid ſtationary points A and E, might become moſt
cute, and as it were abſolutely null and inſenſible.
SIMP. And this alſo is moſt manifeſt to ſenſe.
SALV. Now you know Simplicius that Aſtronomers and
thematicians have found infallible rules by way of Geometry and
Arithmetick, to be able by help of the quantity of theſe angles
B and C, and of their differences, with the additional knowledg
of the diſtance of the two places A and E, to find to a foot the
remoteneſſe of ſublime bodies; provided alwayes that the
ſaid diſtance, and angles be exactly taken.
SIMP. So that if the Rules dependent on Geometry and
nomy be true, all the fallacies and errours that might be met with
in attempting to inveſtigate thoſe altitudes of new Stars or
mets, or other things muſt of neceſſity depend on the diſtance A E,
and on the angles B and C, not well meaſured. And thus all thoſe
differences which are found in theſe twelve workings depend, not
on the deſects of the rules of the Calculations, but on the errours
committed in finding out thoſe angles, and thoſe diſtances, by means
of the Inſtrumental Obſervations.
SALV. True; and of this there is no doubt to be made. Now
it is neceſſary that you obſerve intenſely, how in removing the Star
from B to C, whereupon the angle alwayes grows more acute, the
ray E B G goeth farther and farther off from the ray A B D in
the part beneath the angle, as you may ſee in the line E C F,
whoſe inferiour part E C is more remote from the part A C, than
is the part E B, but it can never happen, that by any whatſoever
immenſe receſſion, the lines A D and E F ſhould totally ſever from
each other, they being finally to go and conjoyn in the Star: and
onely this may be ſaid, that they would ſeparate, and reduce
ſelves to parallels, if ſo be the receſſion ſhould be infinite, which
1caſe is not to be ſuppoſed. But becauſe (obſerve well) the diſtance
of the Firmament, in relation to the ſmallneſſe of the Earth, as
hath been ſaid, is to be accounted, as if it were infinite; therefore
the angle conteined betwixt the two rayes, that being drawn from
the points A and E, go to determine in a fixed Star, is eſteemed
nothing, and thoſe rayes held to be two parallel lines; and
fore it is concluded, that then only may the New Star be affirmed
to have been in the Firmament, when from the collating of the
Obſervations made in divers places, the ſaid angle is, by
tion, gathered to be inſenſible, and the lines, as it were, parallels.
But if the angle be of a conſiderable quantity, the New Star muſt
of neceſſity be lower than thoſe fixed; and alſo than the Moon, in
caſe the angle A B E ſhould be greater than that which would be
made in the Moons centre.
SIMP. Then the remoteneſſe of the Moon is not ſo great, that
a like angle ſhould be ^{*}inſenſible in
* Imperceptible.
SALV. No Sir; nay it is ſenſible, not onely in the Moon, but
in the Sun alſo.
SIMP. But if this be ſo, it's poſſible that the ſaid angle may
be obſerved in the New Star, without neceſſitating it to be
our to the Sun, aſwell as to the Moon.
SALV. This may very well be, yea, and is in the preſent caſe,
as you ſhall ſee in due place; that is, when I ſhall have made plain
the way, in ſuch manner that you alſo, though not very perfect in
Aſtronomical calculations, may clearly ſee, and, as it were, with
your hands feel how that this Authour had it more in his eye to
write in complacency of the Peripateticks, by palliating and
ſembling ſundry things, than to eſtabliſh the truth, by producing
them with naked ſincerity: therefore let us proceed forwards. By
the things hitherto ſpoken, I ſuppoſe that you comprehend very
well how that the diſtance of the new Star can never be
made ſo immenſe, that the angle ſo often named ſhall wholly
appear, and that the two rayes of the Obſervators at the places
A and E, ſhall become altogether parallels: and you may
quently comprehend to the full, that if the calculations ſhould
collect from the obſervations, that that angle was totally null, or
that the lines were truly parallels, we ſhould be certain that the
obſervations were at leaſt in ſome ſmall particular erroneous:
But, if the calculations ſhould give us the ſaid lines to be
ted not only to equidiſtance, that is, ſo as to be parallel, but to
have paſt beyond that terme, and to be dilated more above than
below, then muſt it be reſolutely concluded, that the obſervations
were made with leſſe accurateneſſe, and in a word, to be
ous; as leading us to a manifeſt impoſſibility. In the next place,
you muſt believe me, and ſuppoſe it for true, that two right lines
1which depart from two points marked upon another right line, are
then wider above than below, when the angles included between
them upon that right line are greater than two right angles; and
if theſe angles ſhould be equal to two right angles, the lines would
be parallels; but if they were leſs than two right angles, the lines
would be concurrent, and being continued out would
ly interſect the triangle.
SIMP. Without taking it upon truſt from you, I know the
ſame; and am not ſo very naked of Geometry, as not to know a
Propoſition, which I have had occaſion of reading very often in
Ariſtotle, that is, that the three angles of all triangles are equall to
two right angles: ſo that if I take in my Figure the triangle ABE,
it being ſuppoſed that the line E A is right; I very well conceive,
that its three angles A, E, B, are equal to two right angles; and
that conſequently the two angles E and A are leſſe than two right
angles, ſo much as is the angle B. Whereupon widening the lines
A B and E B (ſtill keeping them from moving out of the points A
and E) untill that the angle conteined by them towards the parts
B, diſappear, the two angles beneath ſhall be equal to two right
angles, and thoſe lines ſhall be reduced to parallels: and if one
ſhould proceed to enlarge them yet more, the angles at the points
E and A would become greater than two right angles.
SALV. You are an Archimedes, and have freed me from the
expence of more words in declaring to you, that whenſoever the
calculations make the two angles A and E to be greater than two
right angles, the obſervations without more adoe will prove
neous. This is that which I had a deſire that you ſhould
ly underſtand, and which I doubted that I was not able ſo to make
out, as that a meer Peripatetick Philoſopher might attain to the
certain knowledg thereof. Now let us go on to what remains.
And re-aſſuming that which even now you granted me, namely,
that the new ſtar could not poſſibly be in many places, but in one
alone, when ever the ſupputations made upon the obſervations of
theſe Aſtronomers do not aſſign it the ſame place, its neceſſary
that it be an errour in the obſervations, that is, either in taking the
altitudes of the pole, or in taking the elevations of the ſtar, or in
the one or other working. Now for that in the many workings
made with the combinations two by two, there are very few of
the obſervations that do agree to place the ſtar in the ſame
tion; therefore theſe few onely may happily be the
ous, but the others are all abſolutely falſe.
SAGR. It will be neceſſary then to give more credit to theſe
few alone, than to all the reſt together, and becauſe you ſay,
that theſe which accord are very few, and I amongſt theſe 12,
do find two that ſo accord, which both make the diſtance of the
1ſtar from the centre of the Earth 4 ſemidiameters, which are theſe,
the fifth and ſixth, therefore it is more probable that the new ſtar
was elementary, than celeſtial.
SALV. You miſtake the point; for if you note well it was not
written, that the diſtance was exactly 4 ſemidiameters, but about
4 ſemidiameters; and yet you ſhall ſee that thoſe two diſtances
differed from each other many hundreds of miles. Here they are;
you ſee that this fifth, which is 13389 Italian miles, exceeds the
ſixth, which is 13100 miles, by almoſt 300 miles.
SAGR. Which then are thoſe few that agree in placing the ſtar
in the ſame ſituation?
SALV. They are, to the diſgrace of this Author five workings,
which all place it in the firmament, as you ſhall ſee in this note,
where I have ſet down many other combinations. But I will grant
the Author more than peradventure he would demand of me, which
is in ſum, that in each combination of the obſervations there is
ſome error; which I believe to be abſolutely neceſſary; for the
obſervations being four in number that ſerve for one working,
that is, two different altitudes of the Pole, and two different
tions of the ſtar, made by different obſervers, in different
ces, with different inſtruments, who ever hath any ſmall know­

ledg of this art, will ſay, that amongſt all the four, it is impoſſible
but there will be ſome error; and eſpecially ſince we ſee that in
taking but one onely altitude of the Pole, with the ſame
ment, in the ſame place, by the ſame obſerver, that hath
peated the obſervation a thouſand times, there will ſtill be a
bation of one, or ſometimes of many minutes, as in this ſame
book you may ſee in ſeveral places. Theſe things preſuppoſed,
I ask you Simplicius whether you believe that this Authour held
theſe thirteen obſervators for wiſe, underſtanding and expert men
in uſing thoſe inſtruments, or elſe for inexpert, and bunglers?
Aſtronomical
struments are very
ſubject to errour.
SIMP. It muſt needs be that he eſteemed them very acute and
intelligent; for if he had thought them unskilful in the buſineſſe,
he might have omitted his ſixth book as inconcluſive, as being
founded upon ſuppoſitions very erroneous; and might take us for
exceſſively ſimple, if he ſhould think he could with their
pertneſſe perſwade us to believe a falſe poſition of his for truth.
SALV. Therefore theſe obſervators being ſuch, and that yet
notwithſtanding they did erre, and ſo conſequently needed
rection, that ſo one might from their obſervations infer the
beſt hints that may be; it is convenient that we apply unto them
the leaſt and neereſt emendations and corrections that may be;
ſo that they do but ſuffice to reduce the obſervations from
ſibility to poſſibility; ſo as v. gr. if one may but correct a
feſt errour, and an apparent impoſſibility of one of their
1vations by the addition or ſubſtraction of two or three minutes, and
with that amendment to reduce it to poſſibility, a man ought
not to eſſay to adjuſt it by the addition or ſubſtraction of fifteen,
twenty, or fifty.
SIMP. I think the Authour would not deny this: for granting
that they are expert and judicious men, it ought to be thought that
they did rather erre little than much.
SALV. Obſerve again; The places where the new Star is
ced, are ſome of them manifeſtly impoſſible, and others poſſible.
Abſolutely impoſſible it is, that it ſhould be an infinite ſpace
riour to the fixed Stars, for there is no ſuch place in the world;
and if there were, the Star there ſcituate would have been
ceptible to us: it is alſo impoſſible that it ſhould go creeping along
the ſuperficies of the Earth; and much leſſe that it ſhould be
within the ſaid Terreſtrial Globe. Places poſſible are theſe that
be in controverſie, it not interferring with our underſtanding, that
a viſible object in the likeneſſe of a Star might be aſwell above the
Moon, as below it. Now whilſt one goeth about to compute by
the way of Obſervations and Calculations made with the utmoſt
certainty that humane diligence can attain unto what its place was,
it is found that the greateſt part of thoſe Calculations make it
more than infinitely ſuperiour to the Firmament, others make it
very neer to the ſurface of the Earth, and ſome alſo under the
ſame; and of the reſt, which place it in ſituations not impoſſible,
none of them agree with each other; inſomuch that it muſt be
confeſſed, that all thoſe obſervations are neceſſarily falſe; ſo that
if we would nevertheleſs collect ſome fruit from ſo many laborious
calculations, we muſt have recourſe to the corrections, amending
all the obſervations.
SIMP. But the Authour will ſay, that of the obſervations that
aſſign to the Star impoſſible places, there ought no account to be
made, as being extreamly erroneous and falſe; and thoſe onely
ought to be accepted, that conſtitute it in places not impoſſible:
and amongſt theſe a man ought to ſeek, by help of the moſt
bable, and moſt numerous concurrences, not if the particular and
exact ſituation, that is, its true diſtance from the centre of the
Earth, at leaſt, whether it was amongſt the Elements, or elſe
mongſt the Cœleſtial bodies.
SALV. The diſcourſe which you now make, is the ſelf ſame
that the Author made, in favour of his cauſe, but with too
ſonable a diſadvantage to his adverſaries; and this is that
pal point that hath made me exceſſively to wonder at the too great
confidence that he expreſſed to have, no leſs of his own authority,
than of the blindneſs and inadvertency of the Aſtronomers; in
favour of whom I will ſpeak, and you ſhall anſwer for the Author.
1And firſt, I ask you, whether the Aſtronomers, in obſerving with
their Inſtruments, and ſeeking v. gr. how great the elevation of a
Star is above the Horizon, may deviate from the truth, aſwell in
making it too great, as too little; that is, may erroneouſly
pute, that it is ſometime higher than the truth, and ſometimes
er; or elſe whether the errour muſt needs be alwayes of one
kinde, to wit, that erring they alwayes make it too much, and
ver too little, or alwayes too little, and never too much?
SIMP. I doubt not, but that it is as eaſie to commit an errour
the one way, as the other.
SALV. I believe the Author would anſwer the ſame. Now of
theſe two kinds of errours, which are contraries, and into which the
obſervators of the new ſtar may equally have fallen, applied to
calculations, one ſort will make the ſtar higher, and the other lower
than really it is. And becauſe we have already agreed, that all
the obſervations are falſe; upon what ground would this
thor have us to accept thoſe for moſt congruous with the truth,
that ſhew the ſtar to have been near at hand, than the others that
ſhew it exceſſively remote?
SIMP. By what I have, as yet, collected of the Authors mind,
I ſee not that he doth refuſe thoſe obſervations, and indagations
that might make the ſtar more remote than the Moon, and alſo
than the Sun, but only thoſe that make it remote (as you your ſelf
have ſaid) more than an infinite diſtance; the which diſtance,
cauſe you alſo do refuſe it as impoſſible, he alſo paſſeth over, as
being convicted of infinite falſhood; as alſo thoſe obſervations
are of impoſſibility. Methinks, therefore, that if you would
vince the Author, you ought to produce ſupputations, more exact,
or more in number, or of more diligent obſervers, which conſtitute
the ſtar in ſuch and ſuch a diſtance above the Moon, or above the
Sun, and to be brief, in a place poſſible for it to be in, like as he
produceth theſe twelve, which all place the ſtar beneath the Moon
in places that have a being in the world, and where it is poſſible for
it to be.
SALV. But Simplicius yours and the Authors Equivocation
lyeth in this, yours in one reſpect, and the Authors in another; I
diſcover by your ſpeech that you have formed a conceit to your
ſelf, that the exorbitancies that are commited in the eſtabliſhing
the diſtance of the Star do encreaſe ſucceſſively, according to the
proportion of the errors that are made by the Inſtrument, in
ing the obſervations, and that by converſion, from the greatneſs
of the exorbitancies, may be argued the greatneſſe of the error;
and that thereforefore hearing it to be infered from ſuch an
vation, that the diſtance of the ſtar is infinite, it is neceſſary, that
the errour in obſerving was infinite, and therefore not to be
1ed, and as ſuch to be refuſed; but the buſineſſe doth not ſucceed
in that manner, my Simplicius, and I excuſe you for not having
comprehended the matter as it is, in regard of your ſmall
ence in ſuch affairs; but yet cannot I under that cloak palliate the
error of the Author, who diſſembling the knowledge of this which
he did perſwade himſelf that we in good earneſt did not
ſtand, hath hoped to make uſe of our ignorance, to gain the
ter credit to his Doctrine, among the multitude of illiterate men.
Therefore for an advertiſement to thoſe who are more credulous
then intelligent, and to recover you from error, know that its
ſible (and that for the moſt part it will come to paſſe) that an
obſervation, that giveth you the ſtar v. gr. at the diſtance of
turn, by the adition or ſubſtraction of but one ſole minute from
the elevation taken with the inſtrument, ſhall make it to become
infinitely diſtant; and therefore of poſſible, impoſſible, and by
converſion, thoſe calculations which being grounded upon thoſe
obſervations, make the ſtar infinitely remote, may poſſibly
times with the addition or ſubduction of one ſole minute, reduce it
to a poſſible ſcituation: and this which I ſay of a minute, may
ſo happen in the correction of half a minute, a ſixth part, and leſs.
Now fix it well in your mind, that in the higheſt diſtances, that is
v. g. the height of Saturn, or that of the fixed Stars, very ſmall
errors made by the Obſervator, with the inſtrument, render the
ſcituation determinate and poſſible, infinite & impoſſible. This doth
not ſo evene in the ſublunary diſtances, and near the earth, where
it may happen that the obſervation by which the Star is collected to
be remote v. g. 4. Semidiameters terreſtrial, may encreaſe or
niſh, not onely one minute but ten, and an hundred, and many
more, without being rendred by the calculation either infinitely
remote, or ſo much as ſuperior to the Moon. You may hence
comprehend that the greatneſſe of the error (to ſo ſpeak)
mental, are not to be valued by the event of the calculation, but
by the quantity it ſelf of degrees and minutes numbred upon the
inſtrument, and theſe obſervations are to be called more juſt or
leſs erroneous, which with the addition or ſubſtraction of fewer
minutes, reſtore the ſtar to a poſſible ſituation; and amongſt the
poſſible places, the true one may be believed to have been that,
bout which a greater number of diſtances concurre upon
ting the more exact obſervations.
SIMP. I do not very well apprehend this which you ſay: nor
can I of my ſelf conceive how it can be, that in greater diſtances,
greater exorbitancies can ariſe from the errour of one minute only,
than in the ſmaller from ten or an hundred; and therefore would
gladly underſtand the ſame.
SALV. You ſhall ſee it, if not Theorically, yet at leaſt
1cally, by this ſhort aſſumption, that I have made of all the
nations, and of part of the workings pretermitted by the Author,
which I have calculated upon this ſame paper.
SAGR. You muſt then from yeſterday, till now, which yet is
not above eighteen hours, have done nothing but compute,
out taking either food or ſleep.
SALV. I have refreſhed my ſelf both thoſe wayes; but truth is,
make theſe ſupputations with great brevity; and, if I may ſpeak
the truth, I have much admired, that this Author goeth ſo farre
bout, and introduceth ſo many computations no wiſe neceſsary to
the queſtion in diſpute. And for a full knowledge of this, and
ſo to the end it may ſoon be ſeen, how that from the obſervations
of the Aſtronomers, whereof this Author makes uſe, it is more
bably gathered, that the new ſtar might have been above the
Moon, and alſo above all the Planets, yea amongſt the fixed ſtars,
and yet higher ſtill than they, I have tranſcribed upon this paper
all the obſervations ſet down by the ſaid Authour, which were
made by thirteen Aſtronomers, wherein are noted the Polar
tude, and the altitudes of the ſtar in the meridian, aſwell the
leſſer under the Pole, as the greater and higher, and they are


1


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1Tycho.gr.m.Altitude of the Pole5558Altitude of the Star8400the greateſt.2757the leaſt.And theſe are, according to the firſt paper: but accor-ding to the ſecond, the greateſt is ------------2745Hainzelius.gr.m.ſec.Altitude of the Pole4822Altitude of the Star76347633457635200940200930200920Peucerus and Sculerus.Landgravius.gr.m.gr.m.Altitude of the pole5154Altitude of the pole5118Altitude of the Star7956Altitude of the Star79302333Camerarius.gr.m.Altitude of the pole5224Altitude of the Star803080278026242824202417HageciusMaurolycus.gr.m.gr.m.Altitude of the pole4822Altitude of the pole3830Altitude of the Star2015Altitude of the Star6200Munocius.Vrſinus.gr.m.gr.m.Altitude of the pole3930Altitude of the pole4924Altitude of the ſtar6730Altitude of the ſtar790011302200Reinholdus.Buchius.gr.m.gr.m.Altitude of the pole5118Altitude of the pole5110Altitude of the ſtar7930Altitude of the ſtar792023022240Gemma.gr.m.Altitude of the pole5050Altitude of the ſtar7945
Now to ſee my whole proceeding, we may begin from theſe
calculations, which are four, omitted by the Author, perhaps
cauſe they make againſt him, in regard they place the ſtar above
the moon by many ſemidiameters of the Earth. The firſt of
which is this, computed upon the obſervations of the Landgrave of
Haſſia, and Tycho; which are, even by the Authors conceſſion,
two of the moſt exact obſervers: and in this firſt, I will declare
the order that I hold in the working; which ſhall ſerve for all the
reſt, in that they are all made by the ſame rule, not varying in any
thing, ſave in the quantity of the given ſummes, that is, in the
number of the degrees of the Poles altitude, and of the new Stars
elevation above the Horizon, the diſtance of which from the
tre of the Earth, in proportion to the ſemidiameter of the terre­
ſtrial Globe is ſought, touching which it nothing imports in this
caſe, to know how many miles that ſemidiameter conteineth;
whereupon the reſolving that, and the diſtance of places where
the obſervations were made, as this Author doth, is but time and
labour loſt; nor do I know why he hath made the ſame, and
cially why at the laſt he goeth about to reduce the miles found,
to ſemidiameters of the Terreſtrial Globe.
SIMP. Perhaps he doth this to finde with ſuch ſmall meaſures,
and with their fractions the diſtance of the Star terminated to three
or four inches; for we that do not underſtand your rules of
metick, are ſtupified in hearing your concluſions; as for inſtance,
whilſt we read; Therefore the new Star or Comet was diſtant
from the Earths centre three hundred ſeventy and three thouſand
eight hundred and ſeven miles; and moreover, two hundred and
eleven, four chouſand ninety ſevenths 373807 211/4097, and upon theſe
preciſe punctualities, wherein you take notice of ſuch ſmall
ters, we do conceive it to be impoſſible, that you, who in our
culations keep an account of an inch, can at the cloſe deceive us ſo
much as an hundred miles.
SALV. This your reaſon and excuſe would paſſe for currant,
if in a diſtance of thouſands of miles, a yard over or under were
of any great moment, and if the ſuppoſitions that we take for
true, were ſo certain, as that they could aſſure us of producing an
indubitable truth in the concluſion; but here you ſee in the twelve
workings of the Author, the diſtances of the Star, which from
them one may conclude to have been different from each other,
(and therefore wide of the truth) for many hundreds and
ſands of miles: now whilſt that I am more than certain, that that
which I ſeek muſt needs differ from the truth by hundreds of miles,
to what purppſe is it to be ſo curious in our calculations, for fear
of miſſing the quantity of an inch? But let us proceed, at laſt,
to the working, which I reſolve in this manner. Tycho, as may be
1ſeen in that ſame note obſerved the ſtar in the polar altitude of 55
degrees and 58 mi. pri. And the polar altitude of the Landgrave
was 51 degrees and 18 mi. pri. The altitude of the ſtar in the
ridian taken by Tycho was 27 degrees 45 mi. pri. The
grave found its altitude 23 degrees 3 mi. pri. The which altitudes
are theſe noted here, as you
gr.m.gr.m.Tycho Pole5558* 2745Landgr. Pole5118* 233
This done, ſubſtract the leſſe from the greater, and there remains
theſe differences here
gr.m.440442Parall.2
Where the difference of the poles altitudes 4 gr. 4 mi. pr.
is leſſe than the difference of the altitudes of the Star 4 gr. 42 mi.
pr. and therefore we have the difference of parallaxes, 0 gr. 2 mi.
pri. Theſe things being found, take the Authours own figure
[Fig. 2.] in which the point B is the ſtation of the Landgrave,
D the ſtation of Tycho, C the place of the ſtar, A the centre
of the Earth, A B E the vertical line of the Landgrave, A D F



of Tycho, and the angle B C D the difference of Parallaxes. And
1becauſe the angle B A D, conteined between the vertical lines, is
equal to the difference of the Polar altitudes, it ſhall be 4gr. 40m.
which I note here apart; and I finde the chord of it by the Table
of Arches and Chords, and ſet it down neer unto it, which is 8142
parts, of which the ſemidiameter A B is 100000. Next, I finde
the angle B D C with eaſe, for the half of the angle B A D, which
is 2 gr. 20 m. added to a right angle, giveth the angle B D F 92 gr.
20 m. to which adding the angle C D F, which is the diſtance from
the vertical point of the greateſt altitude of the Star, which here is
62 gr. 15 m. it giveth us the quantity of the angle B D C,
154 grad. 45 min. the which I ſet down together with its Sine,
taken out of the Table, which is 42657, and under this I note
the angle of the Parallax B C D 0 gr. 2 m. with its Sine 58.
And becauſe in the Triangle B C D, the ſide D B is to the ſide
B C; as the ſine of the oppoſite angle B C D, to the ſine of the
oppoſite angle B D C: therefore, if the line B D were 58. B C
would be 42657. And becauſe the Chord D B is 8142. of thoſe
parts whereof the ſemidiameter B A is 100000. and we ſeek to
know how many of thoſe parts is B C; therefore we will ſay, by
the Golden Rule, if when B D is 58. B G is 42657. in caſe the
ſaid D B were 8142. how much would B C be? I multiply the
ſecond term by the third, and the product is 347313294. which
ought to be divided by the firſt, namely, by 58. and the quotient
ſhall be the number of the parts of the line B C, whereof the
midiameter A B is 100000. And to know how many
ters B A, the ſaid line B C doth contein, it will be neceſſary anew
to divide the ſaid quotient ſo found by 100000. and we ſhall have
the number oſ ſemidiameters conteined in B G. Now the
ber 347313294. divided by 58. giveth 5988160 1/4. as here you
may
gr.m.Its chord 8142 of thoſeAng. B A D440parts, whereof the ſemid.B D F9220A B is an 100000.B D C15445Sines42657B C D02585842657814281428531417062842657341256595834731329457155988160 1/4583473132945717941543
And this divided by 100000. the product is 59
1 |00000| 59 |88160.
But we may much abbreviate the operation, dividing the firſt
quotient found, that is, 347313294. by the product of the
plication of the two numbers 58. and 100000. that
1
5958 000003473132945715
And this way alſo there will come forth 59 5113294/5800000
And ſo many ſemidiameters are contained in the line B C, to
which one being added for the line A B, we ſhall have little leſſe
than 61. ſemidiameters for the two lines A B C; and therefore
the right diſtance from the centre A, to the Star C, ſhall be more
than 60. ſemidiameters, and therefore it is ſuperiour to the Moon,
according to Ptolomy, more than 27. ſemidiameters, and according
to Copernicus, more than 8. ſuppoſing that the diſtance of the
Moon from the centre of the Earth by Copernicus his account is
what the Author maketh it, 52 ſemidiameters. With this ſame
working, I find by the obſervations of Camerarius, and of
ſius, that the Star was ſituate in that ſame diſtance, to wit,
what more than 60. ſemidiameters. Theſe are the obſervations,
and theſe following next after them the

gr.m.gr.m.Altitude of Camerar.5224Altitude of2428the Pole Munoſ.3930the Star1130Differences of the1254Differences1258Polar Altitudesof the alt. of *1254Difference of Parallaxes0004. ang. BCD.gr.m.B A D1254and its chord or ſubtenſe 22466.AnglesB D C16159Sines30930B C D0004116
The Golden Rule.

12246611630930224666739802021946739859_______Diſtance B C 59. and116694873380almoſt 60. ſemidiameters.114410
The next working is made upon two obſervations of Tycho, and
of Munoſius, from which the Star is calculated to be diſtant from
the Centre of the Earth 478 Semidiameters and


gr.m.gr.m.AltitudesTycho.5558Altitude8400of the Pole.Munoſ.3930of the Star.6730Differences of the1628Differ. of the16 30Polar Altitudes.Alt. of the *16 28Difference of Parallax.0 2 and ang. BCDgr.m.B A D.1628its chord28640AnglesB D C.10414Sines96930B C D.0258
The Golden Rule.
589693028640286403877200581587754419386478582776075200450653
Theſe workings following make the Star remote from the
tre, more than 358

1gr.m.gr.m.AltitudesPeucerus5154Altitude7956of the Pole.Munoſius3930of the *473012241226122402gr.m.B A D.1224its chord21600AnglesB D C.10616Sines95996B C D.0258
The Golden
58----95996----21600216005759760095996191992357582073513600333942
From this other working the ſtar is found to be diſtant from the
centre more than 716.

gr.m.gr.m.ſec.AltitudesLandgr.5118Altitude793000of the PoleHainzel.4822of the Star7633452562561525600015gr.m.ſec.B A D25600its Chord5120AnglesB D C1015800Sines97845B C D000157
The Golden
7----97845----5120512019569005784548922571575009664004
Theſe as you ſee are five workings which place the ſtar very
much above the Moon. And here I deſire you to conſider upon
that particular, which even now I told you, namely, that in great
1diſtances, the mutations, or if you pleaſe corrections, of a
ry few minutes, removeth the ſtar a very great way farther off.
As for example, in the firſt of theſe workings, where the
lation made the ſtar 60. ſemidiameters remote from the centre,
with the Parallax of 2. minutes; he that would maintain that it
was in the Firmament, is to correct in the obſervations but onely
two minutes, nay leſſe, for then the Parallax ceaſeth, or
commeth ſo ſmall, that it removeth the ſtar to an immenſe
ſtance, which by all is received to be the Firmament. In the
cond indagation, or working, the correction of leſſe than 4 m.
prim. doth the ſame. In the third, and fourth, like as in the firſt,
two minutes onely mount the ſtar even above the Firmament.
In the laſt preceding, a quarter of a minute, that is 15. ſeconds,
gives us the ſame. But it doth not ſo occur in the ſublunary
tudes; for if you fancy to your ſelf what diſtance you moſt
like, and go about to correct the workings made by the
thour, and adjuſt them ſo as that they all anſwer in the ſame
determinate diſtance, you will find how much greater
ons they do require.
SAGR. It cannot but help us in our fuller underſtanding of
things, to ſee ſome examples of this which you ſpeak of.
SALV. Do you aſſign any whatſoever determinate ſublunary
diſtance at pleaſure in which to conſtitute the ſtar, for with ſmall
ado we may aſſertain our ſelves whether corrections like to theſe,
which we ſee do ſuffice to reduce it amongſt the fixed ſtars, will
reduce it to the place by you aſſigned.
SAGR. To take a diſtance that may favour the Authour, we
will ſuppoſe it to be that which is the greateſt of all thoſe found
by him in his 12 workings; for whilſt it is in controverſie
tween him and Aſtronomers, and that they affirm the ſtar to
have been ſuperiour to the Moon, and he that it was inferiour,
very ſmall ſpace that he proveth it to have been lower, giveth
him the victory.
SALV. Let us therefore take the ſeventh working wrought
upon the obſervations of Tycho and Thaddæus Hagecius, by
which the Authour found the ſtar to have been diſtant from the
centre 32. ſemidiameters, which ſituation is moſt favourable to
his purpoſe; and to give him all advantages, let us moreover
place it in the diſtance moſt disfavouring the Aſtronomers, which
is to ſituate it above the Firmament. That therefore being
poſed, let us ſeek in the next place what corrections it would be
ceſſary to apply to his other 11 workings. And let us begin at the
firſt calculated upon the obſervations of Hainzelius and Mauroice;
in which the Authour findeth the diſtance from the centre about
3. ſemidiameters with the Parallax of 4 gr. 42 m. 30. ſec. Let
1us ſee whether by withdrawing it 20. minutes onely, it will riſe
to the height of 32. ſemidiameters: See the ſhort and true
tion. Multiply the ſine of the angle B D C, by the ſine of the



chord B D, and divide the product, the five laſt figures being cut
off by the ſine of the Parallax, and the quotient will be 28.
midiameters, and an half, ſo that though you make a correction
of 4 gr. 22 min. 30 ſec. taken from 4 gr. 42 min. 30 ſec. it ſhall
not elevate the ſtar to the altitude of 32. ſemidiameters, which
correction for Simplicius his underſtanding it, is of 262. minutes,
and an half.
gr.m.gr.m.ſec.HainzeliusPole4832----*763430MaurolicusPole3830----*62000095214343095200Parallax44230gr.m.ſec.B A D95200Chord17200AnglesB D C1082130Sine94910B C D02000Sine58294910172001898200066437949128582163245200046882
In the ſecond operation made upon the obſervations of
zelius, and Sculerus, with the Parallax of 0 gr. 8 min. 30 ſec.
the ſtar is found in the height of 25. ſemidiameters or
bouts, as may be ſeen in the ſubſequent
1
B DChord6166B D CSines97987B C D2479798761665879225879229798758792224247604187842110311
And bringing back the Parallax 0 gr. 8 m. 30 ſec. to 7 gr.
7 m. whoſe ſine is 204, the ſtar elevateth to 30 ſemidiameters or
thereabouts; therefore the correction of 0 gr. 1 mi. 30 ſec. doth
not
20204604187342196512
Now let us ſee what correction is requiſite for the third
ing made upon the obſervations of Hainzelius and Tycho, which
rendereth the ſtar about 19 ſemidiameters high, with the
rallax of 10 m. pri. The uſual angles and their ſines, and chord
found by the Authour, are theſe next following; and they
move the ſtar (as alſo in the Authours working) 19
meters from the centre of the Earth. It is neceſſary therefore for
the raiſing of it, to diminiſh the Parallax according to the Rule
which he likewiſe obſerveth in the ninth working. Let us
fore ſuppoſe the Parallax to be 6 m. prim. whoſe ſine is 175, and
the diviſion being made, there is found likewiſe leſſe than 31
ſemidiameters for the ſtars diſtance. And therefore the
on of 4 min. prim. is too little to ſerve the Authours
1
B A D736Chord13254AnglesB D C15552Sine40886B C D010Sine291132544088679524106032106032530161830291541903044175541925016181
Let us come to the fourth working, and the reſt with the ſame
rule, and with the chords and ſines found out by the Authour
himſelf; in this the Parallax is 14 m. prim. and the height found
leſſe than 10 ſemidiameters, and diminiſhing the Parallax from
14 min. to 4 min. yet nevertheleſſe you ſee that the ſtar doth not
elevate full 31 ſemidiameters. Therefore 10 min. in 14 min. doth
not

B A DChord8142AnglesB D CSine43235B C DSine4074323581428647017294043235345880301163520193704
In the fifth operation of the Authour we have the ſines and the
chord as you ſee, and the Parallax is 0 gr. 42 m. 30 ſec. which
rendereth the height of the ſtar about 4 ſemidiameters, and
recting the Parallax, with reducing it from 0 gr. 42 m. 30 ſec.
to 0 gr. 5 m. onely, doth not ſuffice to raiſe it to ſo much as 28
midiameters, the correction therefore of 0 gr. 37 m. 30 ſec. is
too
1
B A DChord4034AnglesB D CSine97998B C D12369799840343919922939943919922714539532393210583
In the ſixth operation the chord, the ſines and Parallax are as
followeth, and the ſtar is found to be about 4 ſemidiameters; let
us ſee whether it will be reduced, abating the Parallax from 8 m.
to 1 m. onely; Here is the operation, and the ſtar raiſed but to
27. ſemidiameters or thereabout; therefore the correction of 7 m.
in 8 m. doth not

B DChord1920B D CSine40248B C D 8 gr.Sine233402481920804960362232402482629772761601981
In the eighth operation the chord, the ſines, and the Parallax,
as you ſee, are theſe enſuing, and hence the Authour calculates
the height of the ſtar to be 1. ſemidiameter and an half, with the
Parallax of 43. min. which reduced to 1 min. yet
ing giveth the ſtar leſſe remote than 24. ſemidiameters, the
ction therefore of 42. min. is not
1
B DChord1804B D CSine36643B C DSine2936643180414657229314436643222966103972832
Let us now ſee the ninth. Here is the chord, the ſines and
the Parallax which is 15 m. From whence the Authour
lates the diſtance of the ſtar from the ſuperficies of the Earth
to be leſſe than a ^{*} ſeven and fortieth part of a ſemidiameter,

but this is an errour in the calcultaion, for it cometh forth truly,
as we ſhall ſee here below, more than a ſifth: See here the
tienr is 90/436, which is more than one

* Here the
tine verſion is
neous, making it
a fortieth part of,
&c.
B DChord232B D CSine39046B C DSine4363904623278092117138780924369058672
That which the Authour preſently after ſubjoyns in way of
amending the obſervations, that is, that it ſuſſiceth not to
duce the difference of Parallax, neither to a minute, nor yet
to the eighth part of a minute is true. But I ſay, that neither
will the tenth part of a minute reduce the height of the ſtar to
32. ſemidiameters; for the ſine of the tenth part of a minute,
that is of ſix ſeconds, is 3; by which if we according to our Rule
ſhould divide 90. or we may ſay, if we ſhould divide 9058672.
by 300000. the quotient will be 30 58672/100000, that is little more
than 30. ſemidiameters and an half.
The tenth giveth the altitude of the ſtar one fifth of a
diameter, with theſe angles, ſines, and Parallax, that is, 4 gr.
130 m. which I ſee that being reduced from 4 gr. 30 min. to 2 min.
yet nevertheleſſe it elevates not the ſtar to 29.

B DChord1746B D CSine92050B C D4 gr. 30 m.Sine784692050174605523003682064435920527581607193004414
The eleventh rendereth the ſtar to the Authour remote about
13. ſemidiameters, with the Parallax of 55. min. let us ſee,
ducing it to 20 min. whether it will exalt the ſtar: See here the
calculation elevates it to little leſſe than 33. ſemidiameters, the
correction therefore is little leſſe than 35. min. in 55. min.

B DChord19748B D CSine96166B C Do gr. 55 m.Sine1600961661974863932838466467316286549496166325821899056168153656
The twelfth with the Parallax of 1. gr. 36. min. maketh the
ſtar leſſe high than 6. ſemidiameters, reducing the Parallax to
20 min. it carrieth the ſtar to leſſe than 30. ſemidiameters
ſtance, therefore the correction of 1 gr. 16. min. ſufficeth
1
B DChord17258B D CSine96150B C D1 gr. 36 m.Sine2792172589615086290017258103548155322285821659356700495729
Theſe are the Corrections of the Parallaxes
of the ten workings of the Author, to
reduce the Star to the altitude of
32 Semidiameters.

gr.m.ſec.gr.m.ſec.042230in044230000400in001000001000in001400003700in004230000700in001800004200in004300001450in001500042800in043000003500in005500011600in013600216296.60540240.9765836.540
From hence we ſee, that to reduce the Star to 32.
ters in altitude, it is requiſite from the ſum of the Parallaxes 836.
to ſubtract 756. and to reduce them to 80. nor yet doth that
correction ſuffice.
1
Here we ſee alſo, (as I have noted even now) that ſhould the
Authour conſent to aſſign the diſtance of 32. Semidiameters for
the true height of the Star, the correction of thoſe his 10. workings,
(I ſay 10. becauſe the ſecond being very high, is reduced to the
height of 32. Semidiameters, with 2. minutes correction) to make
them all to reſtore the ſaid Star to that diſtance, would require ſuch
a reduction of Parallaxes, that amongſt the whole number of ſub
ſtractions they ſhould make more than 756 m. pr. whereas in the
5. calculated by me, which do place the Star above the Moon, to
correct them in ſuch ſort, as to conſtitute it in the Firmament,
the correction onely of 10. minutes, and one fourth ſufficeth.
Now adde to theſe, other 5. workings, that place the Star
ciſely in the Firmament, without need of any correction at all,
and we ſhall have ten workings or indagations that agree to place
it in the Firmament, with the correction onely of 5. of them (as
hath been ſeen) but 10. m. and 15 ſec. Whereas for the
on of thoſe 10. of the Authour, to reduce them to the altitude of
32. ſemidiameters, there will need the emendations of 756
nutes in 836. that is, there muſt from the ſumme 836 be
cted 756. if you would have the Star elevated to the altitude of
32. ſemidiameters, and yet that correction doth not fully ſerve.
The workings that immediately without any correction free the
Star from Parallaxes, and therefore place it in the Firmament,
and that alſo in the remoteſt parts of it, and in a word, as high
as the Pole it ſelf, are theſe 5. noted
gr.m.gr.m.Camerar.Polar altit.5224Altit. of the Star8026Peucerus51547956030030gr.m.gr.m.Landgrav.Polar altit.5118Altit. of the Star7930Hainzel.48227634256256gr.m.gr.m.TychoPolar altit.5558Altit. of the Star8400Peucerus515479564444
1gr.m.gr.m.Reinhold.Polar altit.5118Altit. of the Star7930Hainzel.48223634256256gr.m.gr.m.Camerar.Polar altit.5224Altit. of the Star2417Hagecius482220154242
Of the remaining combinations that might be made of the
ſervations of all theſe Aſtronomers, thoſe that make the Stars
lime to an infinite diſtance, are many in number, namely, about
30. more than thoſe who give the Star, by calculation, to be
low the Moon; and becauſe (as it was agreed npon between us) it
is to be believed that the Obſervators have erred rather little than
much, it is a manifeſt thing that the corrections to be applied to
the Obſervaations, which make the ſtar of an infinite altitude, to
reduce it lower, do ſooner, and with leſſer amendment place it in
the Firmament, than beneath the Moon; ſo that all theſe applaud
the opinion of thoſe who put it amongſt the fixed Stars. You may
adde, that the corrections required for thoſe emendations, are
much leſſer than thoſe, by which the Star from an unlikely
mity may be removed to the height more favourable for this
thour, as by the foregoing examples hath been ſeen; amongſt
which impoſſible proximities, there are three that ſeem to remove
the Star from the Earths centre, a leſſe diſtance than one
ameter, making it, as it were, to turn round under ground, and
theſe are thoſe combinations, wherein the Polar altitude of one
of the Obſervators being greater than the Polar altitude of the
other, the elevation of the Star taken by the firſt, is leſſer than the
elation of the Star taken by the latter.
The firſt of theſe is this of the Landgrave with Gemma,
where the Polar altitude of the Landgrave 51 gr. 18 min. is
greater than the Polar altitude of Gemma, which is 50 gr. 50 m.
But the altitude of the Star of the Landgrave 79 gr. 30 min.
is leſſer than that of the Star, of Gemma 79 gr. 45 min.
1gr.m.gr.m.LandgravePolar altit.5118Altit. of the Star7930Gemma50507945
The other two are theſe
gr.m.gr.m.Buſchius.Polar Altitude5110Altit. of the Star7920Gemma.50507945Reinholdus.Polar Altitude5118Altit. of the Star7930Gemma.50507945
From what I have hitherto demonſtrated, you may gueſſe how
much this firſt way of finding out the diſtance of the Star, and
proving it ſublunary introduced by the Authour, maketh againſt
himſelf, and how much more probably and clearly the diſtance
thereof is collected to have been amongſt the more remote fixed
Stars.
SIMP. As to this particular, I think that the inefficacy of the
Authors demonftrations is very plainly diſcovered; But I ſee that all
this was compriſed in but a few leaves of his Book, and it may be,
that ſome other of his Arguments are more concluſive then theſe
firſt.
SALV. Rather they muſt needs be leſſe valid, if we will take
thoſe that lead the way for a proof of the reſt: For (as it is clear)
the uncertainty and inconcluſiveneſſe of thoſe, is manifeſtly
ſerved to derive it ſelf from the errours committed in the
mental obſervations, upon which the Polar Altitude, and height
of the Star was thought to have been juſtly taken, all in effect
having eaſily erred; And yet to find the Altitude of the Pole,
ſtronomers have had Ages of time to apply themſelves to it, at their
leaſure: and the Meridian Altitudes of the Star are eaſier to be
obſerved, as being moſt terminate, and yielding the Obſervator
ſome time to continue the ſame, in regard they change not ſenſibly,
in a ſhort time, as thoſe do that are remote from the Meridian. And
if this be ſo, as it is moſt certain, what credit ſhall we give to
lations founded upon Obſervations more numerous, more difficult
to be wrought, more momentary in variation, and we may add,
with Inſtruments more incommodious and erroneous? Upon a
ſlight peruſal of the enſuing demonſtrations, I ſee that the
putations are made upon Altitudes of the Star taken in different
Vertical Circles, which are called by the Arabick name, Azimuths; in
which obſervations moveable inſtruments are made uſe of, not
ly in the Vertical Circles, but in the Horizon alſo, at the ſame time;
inſomuch that it is requiſite in the ſame moment that the altitude
is taken, to have obſerved, in the Horizon, the diſtance of the
1tical point in which the Star is, from the Meridian; Moreover,
after a conſiderable interval of time, the operation muſt be
peated, and exact account kept of the time that paſſed, truſting
either to Dials, or to other obſervations of the Stars. Such an Olio
of Obſervations doth he ſet before you, comparing them with
ſuch another made by another obſerver in another place with
nother different inſtrument, and at another time; and from this
the Authour ſeeks to collect what would have been, the Elevations
of the Star, and Horizontal Latitudes happened in the time and
hour of the other firſt obſervations, and upon ſuch a coæquation he
in the end grounds his account. Now I refer it to you, what credit
is to be given to that which is deduced from ſuch like workings.
Moreover, I doubt not in the leaſt, but that if any one would
ture himſelf with ſuch tedious computations, he would find, as in
thoſe aforegoing, that there were more that would favour the
verſe party, than the Authour: But I think it not worth the while
to take ſo much pains in a thing, which is not, amongſt thoſe
ry ones, by us underſtood.
SAGR. I am of your Opinion in this particular: But this
neſſe being environed with ſo many intricacies, uncertainties, and
errours, upon what confidence have ſo many Aſtronomers
ly pronounced the new Star to have been ſo high?
SALV. Upon two ſorts of obſervations moſt plain, moſt eaſie,
and moſt certain; one only of which is more than ſufficient to aſſure
us, that it was ſcituate in the Firmament, or at leaſt by a great
diſtance ſuperiour to the Moon. One of which is taken from the
equality, or little differing inequality of its diſtances from the
Pole, aſwell whilſt it was in the loweſt part of the Meridian, as
when it was in the uppermoſt: The other is its having
ly kept the ſame diſtances from certain of the fixed Stars, adjacent
to it, and particularly from the eleventh of Caſſiopea, no more
remote from it than one degree and an half; from which two
ticulars is undoubtedly inferred, either the abſolute want of
lax, or ſuch a ſmalneſſe thereof, that it doth aſſure us with very
expeditious Calculations of its great diſtance from the Earth.
SAGR. But theſe things, were they not known to this Author?
and if he ſaw them, what doth he ſay unto them?
SALV. We are wont to ſay, of one that having no reply that
is able to cover his fault, produceth frivolous excuſes, cerca di
taccarſi alle funi del cielo, [He ſtrives to take hold of the Cords of
Heaven;] but this Authour runs, not to the Cords, but to the Spi­
ders Web of Heaven; as you ſhall plainly ſee in our examination
of theſe two particulars even now hinted. And firſt, that which
ſheweth us the Polar diſtances of the Obſervators one by one, I
have noted down in theſe brief Calculations; For a full
1ſtanding of which, I ought firſt to advertiſe you, that when ever
the new Star, or other Phænomenon is near to the earth, turning
with a Diurnal motion about the Pole, it will ſeem to be farther
off from the ſaid Pole, whilſt it is in the lower part of the
an, then whilſt it is above, as in this Figure [being fig. third of
this Dial.] may be ſeen. In which the point T. denotes the
tre of the Earth; O the place of the Obſervator; the Arch VPC
the Firmament; P. the Pole. The Phænomenon, [or appearance]
moving along the Circle F S. is ſeen one while under the Pole by
the Ray O F C. and another while above, according to the Ray
O S D. ſo that the places ſeen in the Firmament are D. and C. but
the true places in reſpect of the Centre T, are B, and A,
ſtant from the Pole. Where it is manifeſt that the apparent place
of the Phænomenon S, that is the point D, is nearer to the Pole than
the other apparent place C, ſeen along the Line or Ray O F C,
which is the firſt thing to be noted. In the ſecond place you muſt
note that the exces of the apparent inferiour diſtance from the Pole,
over and above the apparent ſuperiour diſtance from the ſaid Pole,
is greater than the Inferiour Parallax of the Phænomenon, that is, I
ſay, that the exceſſe of the Arch C P, (the apparent inferior
ſtance) over and above the Arch P D, (the apparent ſuperior
ſtance) is greater then the Arch C A, (that is the inferiour
lax.) Which is eaſily proved; for the Arch C P. more exceedeth
P D, then P B; P B, being bigger than P D, but P B. is equal to
P A, and the exceſſe of C P, above P A, is the arch, C A,
fore the exceſſe of the arch C P above the arch P D, is
er than the arch C A, which is the parallax of the Phænomenon
placed in F, which was to be demonſtrated. And to give all
vantages to the Author, let us ſuppoſe that the parallax of the ſtar
in F, is the whole exceſſe of the arch C P (that is of the inferiour
diſtance from the pole) above the arch P D (the inferiour
ſtance.) I proceed in the next place to examine that which the
obſervations of all Aſtronomers cited by the Authour giveth us,
amongſt which, there is not one that maketh not againſt himſelf
and his purpoſe. And let us begin with theſe of Buſchius, who
findeth the ſtars diſtance from the pole, when it was ſuperiour, to be
28 gr. 10 m. and the inferiour to be 28 gr. 30 m. ſo that the
ceſſe is 0 gr. 20 m. which let us take (in favour of the Author) as
if it all were the parallax of the ſtar in F, that is the angle T F O.
Then the diſtance from the Vertex [or Zenith] that is the arch
C V, is 67 gr. 20 m. Theſe two things being found, prolong the
line C O, and from it let fall the perpendicular T I, and let us
conſider the triangle T O I, of which the angle I is right angle,
and the angle I O T known, as being vertical to the angle V O C,
the diſtance of the ſtar from the Vertex, Moreover in the triangle
1T I F, which is alſo rectangular, there is known the angle F,
ken by the parallax. Then note in ſome place apart the two
gles I O T and I F T, and of them take the ſines, which are
here ſet down to them, as you ſeen. And becauſe in the triangle
I O T, the ſine T I is 92276. of thoſe parts, whereof the whole
ſine TO is 100000; and moreover in the triangle I F T, the ſine T I
is 582. of thoſe parts, whereof the whole ſine T F is 100000, to
find how many T F is of thoſe parts, whereof T O is 100000;
we will ſay by the Rule of three: If T I be 582. T F is an
100000. but if T I were 92276. how much would T F be.
Let us multiply 92276. by 100000. and the product will be
9227600000. and this muſt be divided by 582. and the quotient
will be 15854982. and ſo many ſhall there be in T F of thoſe
parts, of which there are in T O an 100000. So that if it were
required to know how many lines T O, are in T F, we would
divide 15854982 by 100000. and there will come forth 158. and
very near an half; and ſo many diameters ſhall be the diſtance
of the ſtar F, from the centre T, and to abreviate the
tion, we ſeeing, that the product of the multiplication of 92276.
by 100000, ought to be divided firſt by 582, and then the
tient of that diviſion by 100000. we may without multiplying
92276. by 100000. and with one onely diviſion of the ſine
92276. by the ſine 582. ſoon obtain the ſame ſolution, as may
be ſeen there below; where 92276. divided by 582. giveth us the
ſaid 158 1/2, or thereabouts. Let us bear in mind therefore, that
the onely diviſion of the ſine T I, as the ſine of the angle T O I
by the ſine T I, as the ſine of the angle I F T, giveth us the
ſtance ſought T F, in ſo many diameters T


1gr.m.AnglesI O T6720Sines92276I F T020582T IT FT IT F582100009227601585498258292276000003407002746492978673254141000001585498215858292276340704923
See next that which the obſervations of Peucerus giveth us, in
which the inferiour diſtance from the Pole is 28 gr. 21 m. and the
ſuperiour 28 gr. 2 m. the difference 0 gr. 19 m. and the diſtance
from the vertical point 66 gr. 27 m. from which particulars is
thered the ſtars diſtance from the centre almoſt 166


gr.m.AnglesI A C6627Sines91672I E C019553165 427/55355391672363973124
Here take what Tycho his obſervation holdeth forth to us,
terpreted with greateſt favour to the adverſary; to wit, the
our diſtance from the pole is 28 gr. 13 m. and the ſuperiour 28 gr.
2 m. omitting the difference which is 0 gr. 11 m. as if all were one
Parallax; the diſtance from the vertical point 62 gr. 15 m. Behold
here below the operation, and the diſtance of the ſtar from the
centre found to be 976 9/16

gr.m.AnglesI A C6215Sines88500I E C011320276 9/163208850024181
The obſervation of Reinholdus, which is the next enſuing,
eth us the diſtance of the Star from the Centre 793.


1gr.m.AnglesI A C6658Sines92026I E C04116793 38/116116920261088833
From the following obſervation of the Landgrave, the diſtance
of the Star from the Centre is made to be 1057,

gr.m.AnglesI A C6657Sines92012I E C03871057 53/87879201256635
Two of the moſt favourable obſervations for the Authour
ing taken from Camerarius, the diſtance of the Star from the
tre is found to be 3143

gr.m.AnglesI A C6543Sines91152I E C0129314329911524295
The Obſervation of Munoſius giveth no Parallax, and
fore rendreth the new Star amongſt the higheſt of the fixed. That
of Hainzelius makes it infinitely remote, but with the correction
of an half min. prim. placeth it amongſt the fixed Stars. And the
ſame is collected from Vrſinus, with the correction of 12. min. prim.
The other Aſtronomers have not given us the diſtance above and
below the Pole, ſo that nothing can be concluded from them. By
this time you ſee, that all the obſervations of all theſe men conſpire
againſt the Author, in placing the Star in the Heavenly and
eſt Regions.
SAGR. But what defence hath he for himſelf againſt ſo manifeſt
contradictions?
SALV. He betakes himſelf to one of thoſe weak threads which
I ſpeak of; ſaying that the Parallaxes come to be leſſened by means
of the refractions, which opperating contrarily ſublimate the
nomenon, whereas the Parallaxes abaſe it. Now of what little
ſtead this lamentable refuge is, judge by this, that in caſe that effectof
the refractions were of ſuch an efficacy, as that which not long time
ſince ſome Aſtronomers have introduced, the moſt that they could
work touching the elevating a Phæuomenon above the Horizon
1more than truth, when it is before hand 23. or 24. Degrees high,
would be the leſſening its Parallax about 3. minutes, the which
abatement is too ſmall to pull down the Star below the Moon, and
in ſome caſes is leſſe than the advantage given him by us in
ting that the exceſſe of the inferiour diſtance from the Pole above
the Superiour, is all Parallax, the which advantage is far more clear
and palpable than the effect of Refracton, of the greatneſſe of
which I ſtand in doubt, and not without reaſon. But beſides, I
demand of the Author, whether he thinks that thoſe Aſtronomers,
of whoſe obſervations he maketh uſe, had knowledge of theſe
fects of Refractions, and conſidered the ſame, or no; if they did
know and conſider them, it is reaſonable to think that the, kept
count of them in aſſigning the true Elevation of the Star, making
in thoſe degrees of Altitude diſcovered with the Inſtruments, ſuch
abatements as were convenient on the account of the alterations
made by the Refractions; inſomuch that the diſtances by them
livered, were in the end thoſe corrected and exact, and not the
parent and falſe ones. But if he think that thoſe Authors made
no reflection upon the ſaid Refractions, it muſt be confeſſed, that
they had in like manner erred in determining all thoſe things which
cannot be perfectly adjuſted without allowance for the
ons; amongſt which things one is the preciſe inveſtigation of the
Polar Altitudes, which are commonly taken from the two
an Altitudes of ſome of the fixed Stars that are conſtantly viſible,
which Altitudes will come to be altered by Refraction in the ſame
manner, juſt as thoſe of the new Star; ſo that the Polar Altitude
that is deduced from them, will prove to be defective, and to
take of the ſelf ſame want which this Author aſſigns to the
tudes aſcribed to the new Star, to wit, both that and theſe will
be with equal falſhood placed higher than really they are. But any
ſuch errour, as far as concerns our preſent buſineſſe, doth no
judce at all: For we not needing to know any more, but onely
the difference between the two diſtances of the new Star from the
Pole at ſuch time as it was inferiour and ſuperiour, it is evident that
ſuch diſtances would be the ſame, taking the alteration of
ction commonly for the Star and for the Pole, or for them when
commonly amended. The Authors Argument would indeed have
had ſome ſtrength, though very ſmall, if he had aſſured us that
the Altitude of the Pole had been once preciſely aſſigned, and
rected from the errour depending on refraction, from which
gain the Aſtronomers had not kept themſelves in aſſigning the
titudes of the new Star; but he hath not aſcertained us of that,
nor perhaps could he have done, nor haply, (and this is more
bable) was that caution wanting in the Obſervators.
SAGR. This argument is in my judgment ſufficiently
1ed; therefore tell me how he diſ-ingageth himſelf in the next place
from that particular of the Stars having conſtantly kept the ſame
diſtance from the fixed Stars circumjacent to it.
SALV. He betakes himſelf, in like manner, to two threads, yet
more unable to uphold him than the former: one of which is
wiſe faſtened to refraction, but ſo much leſs firmly, in that he
ſaith, that refraction operating upon the new Star, and ſublimating
it higher than its true ſituation, maketh the ſeeming diſtances
tain to be diſtinguiſhed from the true, when compared to the
cumpoſed fixed Stars that environ it. Nor can I ſufficiently
mire how he can diſſemble his knowing how that the ſame
ction will work alike upon the new Star, as upon the antient one
its neighbour, elevating both equally, ſo as that ſuch a like
dent altereth not the ſpace betwixt them. His other ſubterfuge is
yet more unhappy, and carryeth with it much of ridiculous, it
ing founded upon the errour that may ariſe in the inſtrumen
peration it ſelf; whilſt that the Obſervator not being able to
conſtitute the centre of the eyes pupil in the centre of the
tant (an Inſtrument imployed in obſerving the diſtance between
two Stars) but holding it elevated above that centre, as much as
the ſaid pupil is diſtant from I know not what bone of the cheek,
againſt which the end of the Inſtrument reſteth, there is formed
in the eye an angle more acute than that which is made by the ſides
of the Inſtrument; which angle of rayes differeth alſo from it
ſelf, at ſuch time as a man looketh upon Stars, not much elevated
above the Horizon, and the ſame being afterwards placed at a
great height; that angle, ſaith he, is made different, while the
ſtrument goeth aſcending, the head ſtanding ſtill: but if in
ting the Inſtrument, the neck ſhould bend backwards, and the
head go riſing, together with the Inſtrument, the angle would then
continue the ſame. So that the Authours anſwer ſuppoſeth that
the Obſervators in uſing the Inſtrument have not raiſed the head,
as they ought to have done; a thing which hath nothing of
hood in it. But granting that ſo it had been, I leave you to judge
what difference can be between two acute angles of two
ral triangles, the ſides of one of which triangles are each four
[Italian] Braces [i.e. about three Engliſh yards] and thoſe of the
other, four braces within the quantity of the diameter of a Pea;
for the differences cannot be abſolutely greater between the length
of the two viſive rayes, whilſt the line is drawn perpendicularly
from the centre of the pupil, upon the plain of the Rule of the
Sextant (which line is no bigger than the breath of the thumb)
and the length of the ſame rayes, whilſt elevating the Sextant,
without raiſing the head together with it, that ſame line no longer
falleth perpendicularly upon the ſaid plane, but inclineth, making
1the angle towards the circumference ſomething acute. But wholly
to free this Authour from theſe unhappy lies, let him know, (in
gard it appears that he is not very skilful in the uſe of
call Inſtruments) that in the ſides of the Sextant or Quadrant

there are placed two ^{*} Sights, one in the centre, and the other at
the other at the oppoſite end, which are raiſed an inch or more
bove the plane of the Rule; and through the tops of thoſe ſights
the ray of the eye is made to paſſe, which eye likewiſe is held an
hands breadth or two, or it may be more, from the Inſtrument; ſo
that neither the pupil, nor any bone of the cheek, nor of the whole
body toucheth or ſtayeth it ſelf upon the Inſtrument, nor much
leſſe is the Inſtrument upheld or mounted in the armes, eſpecially
if it be one of thoſe great ones, as is uſual, which weighing tens,
hundreds, and alſo thouſands of pounds, are placed upon very
ſtrong feet or frames: ſo that the whole objection vaniſheth.
Theſe are the ſubterfuges of this Authour, which, though they were
all of ſteel, would not ſecure him the hundredth part of a minute;
and with theſe he conceits to make us believe, that he hath
penſated that difference, which importeth more than an hundred
minutes; I mean, that of the not obſerving a notable difference
in the diſtances between one of the fixed ſtars, and the new ſtar in
in any of their circulations; which, had it been neer to the Moon,
it ought to have been very conſpicuous to the meer ſight, without
any Inſtrument, eſpecially comparing it with the eleventh of
ſiopeia, its neighbour, within 1 gr. 30 m. which ought to have
ried from it more than two diameters of the moon, as the more
intelligent Aſtronomers of t' oſe times do well note.
* Traguardi.
SAGR. Methinks I ſee that unfortunate Husbandman, who
ter all his expected crops, have been beaten down and deſtroyed by
a ſtorm, goeth up and down with a languiſhing and down-caſt
look, gleaning up every ſmall ear that would not ſuffice to keep a
chicken alive one ſole day.
SALV. Truly, this Authour came out too ſlenderly provided
with armes againſt the aſſailants of the Heavens inalterability, and
with too brittle a chain attempted to pull down the new ſtar of
Caſſiopeia from the higheſt Regions, to theſe ſo low and
ry. And for that I think that we have ſufficiently demonſtrated
the vaſt difference that is between the arguments of thoſe
nomers, and of this their Antagoniſt, it will be convenient that we
leave this particular, and return to our principal matter; in which
there preſents it ſelf to our conſideration the annual motion
monly aſcribed to the Sun, but by Aristarchus Samius firſt of all,
and after by Copernicus taken from the Sun, and transferred upon
the Earth; againſt which Hypotheſis, methinks I ſee Simplicius to
come ſtrongly provided, and particularly with the ſword and
1buckler of the little Treatiſe of Concluſions, or Diſquiſitions
thematical, the oppugnations of which it would be good to
gin to produce.
SIMP. I will, if you ſo pleaſe, reſerve them to the laſt, as thoſe
that are of lateſt invention.
SALV. It will therefore be neceſſary, that in conformity to the
method hitherto obſerved, you do orderly, one by one, propound
the arguments, on the contrary, aſwell of Ariſtotle, as of the
ther ancients, which ſhall be my task alſo, that ſo nothing may
ſcape our ſtrict conſideration and examination; and likewiſe
gredus, with the vivacity of his wit, ſhall interpoſe his thoughts, as
he ſhall finde himſelf inclined.
SAGR. I will do it with my wonted freedome; and your
mands ſhall oblige you to excuſe me in ſo doing.
SALV. The favour will challenge thanks, and not an excuſe.
But now let Simplicius begin to propoſe thoſe doubts which
ſwade him from believing that the Earth, in like manner, as the
other pianets, may move round about a fixed centre.
SIMP. The firſt and greateſt difficulty is the repugnance and
incompatibility that is between being in the centre, and being far
from it; for if the Terreſtrial Globe were to move in a year by
the circumference of a circle, that is, under the Zodiack, it is
poſſible that it ſhould, at the ſame time, be in the centre of the
diack; but that the Earth is in the ſaid centre Aristotle, Ptolomy,
and others have many wayes proved.
SALV. You very well argue, aud there is no queſtion but that
one that would make the Earth to move in the circumference of a
circle, muſt firſt of neceſſity prove, that it is not in the centre of
that ſame circle; it now followeth, that we enquire, whether the
Earth be, or be not in that centre, about which, I ſay, that it
neth, and you ſay that it is fixed; and before we ſpeak of this, it
is likewiſe neceſſary that we declare our ſelves, whether you and I
have both the ſame conceit of this centre, or no. Therefore tell
me, what and where is this your intended centre?
SIMP. When I ſpeak of the centre, I mean that of the
verſe, that of the World, that of the Starry Sphere.
SALV. Although I might very rationally put it in diſpute,
ther there be any ſuch centre in nature, or no; being that neither

you nor any one elſe hath ever proved, whether the World be
nite and figurate, or elſe infinite and interminate; yet nevertheleſs
granting you, for the preſent, that it is finite, and of a terminate
Spherical Figure, and that thereupon it hath its centre; it will be
requiſite to ſee how credible it is that the Earth, and not rather
ſome other body, doth poſſeſſe the ſaid centre.
It hath not been
hitherto proved by
any, whether the
World be finite or
infinite.
SIMP. That the world is finite, terminato, and ſpherical, Ari-
1ſtotle proveth with an hundred
The
tions of Ariſtotle
to Prove that the
Vniverſe is finite,
are all nullified by
denying it to be
moveable.
SALV. All which in the end are reduced to one alone, and that
one to none at all; for if I deny his aſſumption, to wit, that the
Univerſe is moveable, all his demonſtrations come to nothing, for
he onely proveth the Univerſe to be finite and terminate, for that
it is moveable. But that we may not multiply diſputes, let it be
granted for once, that the World is finite, ſpherical, and hath
its centre. And ſeeing that that centre and figure is argued from
its mobility, it will, without doubt, be very reaſonable, if from the
circular motions of mundane bodies we proceed to the particular
inveſtigation of that centres proper place: Nay Ariſtotle himſelf

hath argued and determined in the ſame manner, making that
ſame to be the centre of the Univerſe about which all the
leſtial Spheres revolve, and in which he beleived the Terreſtrial
Globe to have been placed. Now tell me Simplicius, if Ariſtotle

ſhould be conſtrained by evident experience to alter in part this
his diſpoſure and order of the Univerſe, and confeſſe himſelf to
have been deceived in one of theſe two propoſitions, namely,
ther in placing the Earth in the centre, or in ſaying, that the
Cœleſtial Spheres do move about that centre, which of the two
confeſſions think you would he chooſe?
Ariſtotle makes
that point to be the
centre of the
verſe about which
all the Celeſtial
Spheres do revolve.
A queſtion is
put, in caſe that
if Ariſtotle were
forced to receive
one of two
tions that make
gainſt his doctrine,
which he would
admit.
SIMP. I believe, that if it ſhould ſo fall out, the
ticks.
SALV. I do not ask the Peripateticks, I demand of Ariſtotle,
for as to thoſe, I know very well what they would reply; they, as
obſervant and humble vaſſals of Ariſtotle, would deny all the
periments and all the obſervations in the World, nay, would alſo
refuſe to ſee them, that they might not be forced to acknowledg
them, and would ſay that the World ſtands as Ariſtotle writeth,
and not as nature will have it, for depriving them of the ſhield
of his Authority, with what do you think they would appear in the
field? Tell me therefore what you are perſwaded Ariſtotle
ſelf would do in the caſe.
SIMP. To tell you the truth, I know not how to reſolve
which of the two inconveniences is to be eſteemed the leſſer.
SALV. Apply not I pray you this term of inconvenience to a
thing which poſſibly may of neceſſity be ſo. It was an
ence to place the Earth in the centre of the Cœleſtial revolutions;
but ſeeing you know not to which part he would incline, I
ſteeming him to be a man of great judgment, let us examine
which of the two choices is the more rational, and that we will
hold that Ariſtotle would have received. Reaſſuming therefore our
diſcourſe from the beginning, we ſuppoſe with the good liking of
Ariſtotle, that the World (of the magnitude of which we have
no ſenſible notice beyond the fixed ſtars) as being of a ſpherical
1figure; and moveth circularly, hath neceſſarily, and in reſpect of
its figure a centre; and we being moreover certain, that within
the ſtarry Sphere there are many Orbs, the one within another,
with their ſtars, which likewiſe do move circulary, it is in diſpute
whether it is moſt reaſonable to believe and to ſay that theſe
teined Orbs do move round the ſaid centre of the World, or elſe
about ſome other centre far remote from that? Tell me now
plicius what you think concerning this particular.
SIMP. If we could ſtay upon this onely ſuppoſition, and that

we were ſure that we might encounter nothing elſe that might
ſturb us, I would ſay that it were much more reaſonable to
firm that the Orb containing, and the parts contained, do all
move about one common centre, than about divers.
Its more
nal that the Orb
conteining, and the
parts conteined, do
move all about one
centre, than uoon
divers.
SALV. Now if it were true that the centre of the World is the

ſame about which the Orbs of mundane bodies, that is to ſay, of
the Planets, move, it is moſt certain that it is not the Earth, but
the Sun rather that is fixed in the centre of the World. So that as
to this firſt ſimple and general apprehenſion, the middle place
belongeth to the Sun, and the Earth is as far remote from the
centre, as it is from that ſame Sun.
If the centre of
the World be the
ſame with that
bout which the
nees move the Sun
and not the Earth
is placed in it.
SIMP. But from whence do you argue that not the Earth, but
the Sun is in the centre of the Planetary revolutions?
SALV. I infer the ſame from moſt evident, and therefore
ceſſarily concludent obſervations, of which the moſt palpable to

exclude the Earth from the ſaid centre, and to place the Sun
therein, are, the ſeeing all the Planets one while neerer and
ther while farther off from the Earth with ſo great differences, that
for example, Venus when it is at the fartheſt, is ſix times more
remote from us, than when it is neereſt, and Mars riſeth almoſt
eight times as high at one time as at another. See therefore
ther Ariſtotle was not ſomewhat miſtaken in thinking that it was
at all times couidiſtant from us.
Obſervations from
whence it is
lected that the Sun
and not the Earth
is in the centre of
the Celeſtial
lutions.
SIMP. What in the next place are the tokens that their
ons are about the Sun?
SALV. It is argued in the three ſuperiour planets Mars,
ter, and Saturn, in that we find them alwayes neereſt to the
Earth when they are in oppoſition to the Sun, and fartheſt off
when they are towards the conjunction, and this approximatian
and receſſion importeth thus much that Mars neer at hand,
peareth very neer 60 times greater than when it is remote. As to

Venus in the next place, and to Mercury, we are certain that
they revolve about the Sun, in that they never move far from
him, and in that we ſee them one while above and another while

below it, as the mutations of figure in Venus neceſſarily argueth.
Tonchiug the Moon it is certain, that ſhe cannot in any way
1ſeperate from the Earth, for the reaſons that ſhall be more
ly alledged hereafter.
The mutation
of figure in Venus
argueth its motion
to be about the Sun.
The Moon
not ſeperate from
the Earth.
SAGR. I expect that I ſhall hear more admirable things that
depend upon this annual motion of the Earth, than were thoſe
dependant upon the diurnal
The annual
tion of the Earth
mixing with the
motions of the
ther Planets
duce extravagant
appearances.
SALV. You do not therein erre: For as to the operation of
the diurnal motion upon the Celeſtial bodies, it neither was, nor
can be other, than to make the Univerſe ſeem to run precipitately
the contrary way; but this annual motion intermixing with the
particular motions of all the planets, produceth very many
travagancies, which have diſarmed and non-pluſt all the greateſt
Scholars in the World. But returning to our firſt general
henſions, I reply that the centre of the Celeſtial converſions of
the five planets Saturn, Jupiter, Mars, Venus and Mercury, is
the Sun; and ſhall be likewiſe the centre of the motion of the
Earth, if we do but ſucceed in our attempt of placing it in
ven. And as for the Moon, this hath a circular motion about the
Earth, from which (as I ſaid before) it can by no means alienate
it ſelf, but yet doth it not ceaſe to go about the Sun together with
the Earth in an annual motion.
SIMP. I do not as yet very well apprehend this ſtructure, but
it may be, that with making a few draughts thereof, one may
ter and more eaſily diſcourſe concerning the ſame.
SALV. Tis very true: yea for your greater ſatisfaction and
miration together, I deſire you, that you would take the pains
to draw the ſame; and to ſee that although you think you do not
apprehend it, yet you very perfectly underſtand it; And onely
by anſwering to my interrogations you ſhall deſigne it punctually.

Take therefore a ſheet of paper and Compaſles; And let this
white paper be the immenſe expanſion of the Univerſe; in which
you are to diſtribute and diſpoſe its parts in order, according as
reaſon ſhall direct you. And firſt, in regard that without my
ſtruction you verily believe that the Earth is placed in this
verſe, therefore note a point at pleaſure, about which you
tend it to to be placed, and mark it with ſome characters.
The Syſteme of
the Univerſe
ſigned from the
pearances.
SIMP. Let this mark A be the place of the Terreſtrial Globe.
SALV. Very well. I know ſecondly, that you underſtand
fectly that the ſaid Earth is not within the body of the Sun, nor
ſo much as contiguous to it, but diſtant for ſome ſpace from the
ſame, and therefore aſſign to the Sun what other place you beſt
like, as remote from the Earth as you pleaſe, and mark this in
like manner.
SIMP. Here it is done: Let the place of the Solar body
be O.
SALV. Theſe two being conſtituted, I deſire that we may
1think of accomodating the body of Venus in ſuch a manner that
its ſtate and motion may agree with what ſenſible experiments do
ſhew us; and therefore recall to mind that. which either by the
paſt diſcourſes, or your own obſervations you have learnt to
fal that ſtar, and afterwards aſſign unto it that ſtate which you
think agreeth with the ſame.
SIMP. Suppoſing thoſe Phænomena expreſſed by you, and
which I have likewiſe read in the little treatiſe of Concluſions, to
18[Figure 18]
be true, namely, that that ſtar never recedes from the Sun beyond
ſuch a determinate ſpace of 40 degrees or thereabouts, ſo as that
it never cometh either to appoſition with the Sun, or ſo much as
to quadrature, or yet to the ſextile aſpect; and more than that,

ſuppoſing that it ſheweth at one time almoſt 40 times greater than
at another; namely, very great, when being retrograde, it goeth to
the veſpertine conjnnction of the Sun, and very ſmall when with a
1motion ſtraight forwards, it goeth to the matutine conjunction;
and moreover it being true, that when it appeareth bigge it ſhews
with a corniculate figure, and when it appeareth little, it ſeems
perfectly round, theſe appearances, I ſay, being true, I do not ſee
how one can chooſe but affirm the ſaid ſtar to revolve in a circle

bout the Sun, for that the ſaid circle cannot in any wiſe be ſaid
to encompaſſe or to contain the Earth within it, nor to be
our to the Sun, that is between it and the Earth, nor yet
riour to the Sun. That circle cannot incompaſſe the Earth,
cauſe Venus would then ſometimes come to oppofition with the
Sun; it cannot be inferiour, for then Venus in both its
ons with the Sun would ſeem horned; nor can it be ſuperiour,
for then it would alwayes appear round, and never cornicular;
and therefore for receit of it I will draw the circle CH, about
the Sun, without encompaſſing the Earth.
Venus very greas
towards the
ctive conjunction
and very ſmall
wards the
tine.
Venus
rily proved to move
about the Sun.
SALV. Having placed Venus, it is requiſite that you think of
Mercury, which, as you know, alwayes keeping about the Sun,
doth recede leſſe diſtance from it than Venus; therefore conſider
with your ſelf, what place is moſt convenient to aſſign
The revolution of
Mercury concluded
to be about the Sun,
within the Orb of
Venus.
SIMP. It is not to be queſtioned, but that this Planet
ing Venus, the moſt commodious place for it will be, a leſſer
cle within this of Venus, in like manner about the Sun, being
that of its greateſt vicinity to the Sun, an argument, an evidence
ſufficiently proving the vigour of its illumination, above that of
Venus, and of the other Planets, we may therefore upon theſe
conſiderations draw its Circle, marking it with the Characters
BG.
Mars neceſſarily
includeth within its
Orb the Earth, and
alſo the Sun.
SALV. But Mars, Where ſhall we place it?
SIMP. Mars, Becauſe it comes to an oppoſition with the Sun,
its Circle muſt of neceſſity encompaſs the Earth; But I ſee that it
muſt neceſſarily encompaſs the Sun alſo, for coming to
on with the Sun, if it did not move over it, but were below it, it
would appear horned, as Venus and the Moon; but it ſhews
wayes round, and therefore it is neceſſary, that it no leſs includ­

eth the Sun within its circle than the Earth. And becauſe I
member that you did ſay, that when it is in oppoſition with the
Sun, it ſeems 60 times bigger than when it is in the conjunction,
me thinks that a Circle about the Centre of the Sun, and that
eth in the earth, will very well agree with theſe Phænomena,
which I do note and mark D I, where Mars in the point D, is near
to the earth, and oppoſite to the Sun; but when it is in the point
I, it is at Conjuction with the Sun, but very far from the Earth.

And becauſe the ſame appearances are obſerved in Jupiter and
Saturn, although with much leſſer difference in Jupiter than in
Mars, and with yet leſſe in Saturn than in Jupiter; me thinks I
1underſtand that we ſhould very commodiouſly ſalve all the
nomena of theſe two Planets, with two Circles, in like manner,
drawn about the Sun, and this firſt for Jupiter, marking it E L, and
another above that for Saturn marked F
Mars at its
ſition to the Sun
ſhews to be ſixty
times bigger than
towards the
junction.
Jupiter and
turn do likewiſe
compaſſe the Earth,
and the Sun.
The
tion and receſſion of
the three ſuperiour
Planets, importeth
double the Suns
ſtance.
SALV. You have behaved your ſelf bravely hitherto. And
becauſe (as you ſee) the approach and receſſion of the three
periour Planets is meaſured with double the diſtance between the
Earth and Sun, this maketh greater difference in Mars than in Ju-

piter, the Circle D I, of Mars, being leſſer than the Circle E L,
of Jupiter, and likewiſe becauſe this E L, is leſſe than this Circle
F M, of Saturn, the ſaid difference is alſo yet leſſer in Saturn than
in Jupiter, and that punctually anſwereth the Phænomena.
It remains now that you aſſign a place to the Moon.
The difference of
the apparent
nitude leſſe in
turn, than in
ter, an dn Jupiter
than in Mars, and
why.
SIMP. Following the ſame Method (which ſeems to me very

concluſive) in regard we ſee that the Moon cometh to conjunction
and oppoſition with the Sun, it is neceſſary to ſay, that its circle
encompaſſeth the Earth, but yet doth it not follow, that it muſt
environ the Sun, for then at that time towards its conjunction, it
would not ſeem horned, but alwayes round and full of Light.
Moreover it could never make, as it often doth, the Eclipſe of the
Sun, by interpoſing betwixt it and us; It is neceſſary therefore
to aſſign it a circle about the Earth, which ſhould be this N P, ſo
that being conſtituted in P, it will appear from the Earth A, to be
in conjunction with the Sun, and placed in N, it appeareth oppoſite
to the Sun, and in that poſition it may fall under the Earths
dow, and be obſcured.
The Moons Orb
invironeth the
Earth, but not the
Sun.
SALV. Now, Simplicius, what ſhall we do with the fixed
ſtars? Shall we ſuppoſe them ſcattered through the immenſe
ſes of the Univerſe, at different diſtances, from any one
nate point; or elſe placed in a ſuperficies ſpherically diſtended
bout a centre of its own, ſo that each of them may be
diſtant from the ſaid
The probable
ſituation of the
fixed ſtars.
SIMP. I would rather take a middle way; and would aſſign
them an Orb deſcribed about a determinate centre and comprized
within two ſpherical ſuperficies, to wit, one very high, and
cave, and the other lower, and convex, betwixt which I would

conſtitute the innumerable multitude of ſtars, but yet at divers
titudes, and this might be called the Sphere of the Univerſe,
ing within it the Orbs of the planets already by us deſcribed.
Which ought to
be accounted the
ſphere of the
verſe.
SALV. But now we have all this while, Simplicius, diſpoſed the
mundane bodies exactly, according to the order of Copernicus,
and we have done it with your hand; and moreover to each of
them you have aſſigned peculiar motions of their own, except to
the Sun, the Earth, and ſtarry Sphere; and to Mercury with
Venus, you have aſcribed the circular motion about the Sun,
1without encompaſſing the Earth; about the ſame Sun you make
the three ſuperiour Planets Mars, Jupiter, and Saturn, to move,
comprehending the Earth within their circles. The Moon in the
next place can move in no other manner than about the Earth,
without taking in the Sun, and in all theſe motions you agree alſo
with the ſame Copernicus. There remains now three things to be
decided between the Sun, the Earth, and fixed ſtars, namely,

Reſt, which ſeemeth to belong to the Earth; the annual motion
under the Zodiack, which appeareth to pertain to the Sun; and the
diurnal motion, which ſeems to belong to the Starry Sphere, and
to be by that imparted to all the reſt of the Univerſe, the Earth
excepted, And it being true that all the Orbs of the Planets, I

mean of Mercury, Venus, Mars, Jupiter, and Saturn, do move
about the Sun as their centre; reſt ſeemeth with ſo much more
reaſon to belong to the ſaid Sun, than to the Earth, in as much
as in a moveable Sphere, it is more reaſonable that the centre
ſtand ſtill, than any other place remote from the ſaid centre; to
the Earth therefore, which is conſtituted in the midſt of
able parts of the Univerſe, I mean between Venus and Mars, one
of which maketh its revolution in nine moneths, and the other in
two years, may the motion of a year very commodiouſly be

ſigned, leaving reſt to the Sun. And if that be ſo, it followeth
of neceſſary conſequence, that likewiſe the diurnal motion
longeth to the Earth; for, if the Sun ſtanding ſtill, the Earth
ſhould not revolve about its ſelf, but have onely the annual
tion about the Sun, our year would be no other than one day and
one night, that is ſix moneths of day, and ſix moneths of night,
as hath already been ſaid. You may conſider withal how
diouſly the precipitate motion of 24 hours is taken away from
the Univerſe, and the fixed ſtars that are ſo many Suns, are made
in conformity to our Sun to enjoy a perpetual reſt. You ſee
over what facility one meets with in this rough draught to render
the reaſon of ſo great appearances in the Celeſtial bodies.
Reſt, the annual
motion and the
urnal ought to be
diſtributed
twixt the Sun,
Earth, and
mament.
In a moveable
ſphere, it ſeemeth
more veaſonable
that its centre be
ſtable, than any
ther of its parts.
Granting to the
Earth the annual,
it muſt of neceſſity
alſo have the
nal motion
ed to it.
SAGR. I very well perceive that facility, but as you from this
ſimplicity collect great probabilities for the truth of that Syſtem,
others haply could make thence contrary deductions; doubting,
not without reaſon, why that ſame being the ancient Syſteme of
Pythagoreans, and ſo well accommodated to the Phænomena,
hath in the ſucceſſion of ſo many thouſand years had ſo few
lowers, and hath been even by Ariſtotle himſelf refuted, and
ſince that Copernicus himſelf hath had no better fortune.
SALV. If you had at any time been aſſaulted, as I have been,
many and many a time, with the relation of ſuch kind of frivolous
reaſons, as ſerve to make the vulgar contumacious, and difficult to
be perſwaded to hearken, (I will not ſay to conſent) to this
1ty, I believe that you wonder at the paucity of thoſe who are
lowers of that opinion would be much diminiſhed. But ſmall

gard in my judgement, ought to be had of ſuch thick ſculs, as think
it a moſt convincing proof to confirm, and ſteadfaſtly ſettle them
in the belief of the earths immobility, to ſee that if this day they
cannot Dine at Conſtantinople, nor Sup in Jappan, that then the
Earth as being a moſt grave body cannot clamber above the Sun,
and then ſlide headlong down again; Of ſuch as theſe I ſay,
whoſe number is infinite, we need not make any reckoning, nor
need we to record their foolieries, or to ſtrive to gain to our ſide
as our partakers in ſubtil and ſublime opinions, men in whoſe
finition the kind onely is concerned, and the difference is wanting.
Moreover, what ground do you think you could be able to gain,
with all the demonſtrations of the World upon brains ſo ſtupid,
as are not able of themſelves to know their down right follies? But
my admiration, Sagredus, is very different from yours, you
der that ſo few are followers of the Pythagorean Opinion; and I
am amazed how there could be any yet left till now that do
brace and follow it: Nor can I ſufficiently admire the eminencie of

thoſe mens wits that have received and held it to be true, and with
the ſprightlineſſe of their judgements offered ſuch violence to their
own ſences, as that they have been able to prefer that which their
reaſon dictated to them, to that which ſenſible experiments
preſented moſt manifeſtly on the contrary. That the reaſons againſt
the Diurnal virtiginous revolution of the Earth by you already
amined, do carry great probability with them, we have already
ſeen; as alſo that the Ptolomaicks, and Ariſtotelicks, with all their
Sectators did receive them for true, is indeed a very great argument
of their efficacie; but thoſe experiments which apertly contradict
the annual motion, are of yet ſo much more manifeſtly repugnant,

that (I ſay it again) I cannot find any bounds for my admiration,
how that reaſon was able in Ariſtarchus and Copernicus, to
mìt ſuch a rape upon their Sences, as in deſpight thereof, to make
her ſelf miſtreſs of their credulity.
Diſcourſes more
than childiſh, ſerve
to keep fools in the
opinion of the
Earths ſtability.
A declaration
of the
lity of Copernicus
his opinion.
Reaſons and
courſe in
cus and
cus prevailed over
manifeſt ſence.
SAGR. Are we then to have ſtill more of theſe ſtrong
ons againſt this annual motion?
SALV. We are, and they be ſo evident and ſenſible, that if a
ſence more ſublime and excellent than thoſe common and vulgar,
did not take part with reaſon, I much fear, that I alſo ſhould have
been much more averſe to the Copernican Syſteem than I have been
ſince the time that a clearer lamp than ordinary hath enlightned
me.
SAGR. Now therefore Salviatus, let us come to joyn battail
for every word that is ſpent on any thing elſe, I take to be caſt
way.
1
SALV. I am ready to ſerve you. You have already ſeen me
draw the form of the Copernican Syſteme; againſt the truth of

which Mars himſelf, in the firſt place, makes an hot charge; who, in
caſe it were true, that its diſtances from the earth ſhould ſo much
vary, as that from the leaſt diſtance to the greateſt, there were
twice as much difference, as from the earth to the Sun; it would be
neceſſary, that when it is neareſt unto us, its diſcus would ſhew
more than 60. times bigger than it ſeems, when it is fartheſt from
us; nevertheleſs that diverſity of apparent magnitude is not to be
ſeen, nay in its oppoſition with the Sun, when its neareſt to the
Earth, it doth not ſhew ſo much as quadruple and quintuple in
bigneſs, to what it is, when towards the conjunction it cometh to
be occulted under the Suns rayes. Another and greater difficulty
doth Venus exhibit; For if revolving about the Sun, as Copernicus

affirmeth, it were one while above, & another while below the ſame,
receding and approaching to us ſo much as the Diameter of the
cle deſcribed would be, at ſuch time as it ſhould be below the Sun,
and neareſt to us, its diſcus would ſhew little leſs than 40 times
ger than when it is above the Sun, near to its other conjunction; yet
nevertheleſſe, the difference is almoſt imperceptible Let us add

other difficulty, that in caſe the body of Venus be of it ſelf dark, and
onely ſhineth as the Moon, by the illumination of the Sun, which
ſeemeth moſt reaſonable; it would ſhew forked or horned at ſuch
time as it is under the Sun, as the Moon doth when ſhe is in like
manner near the Sun; an accident that is not to be diſcovered in
her. Whereupon Copernicus affirmeth, that either ſhe is light of

her ſelf, or elſe that her ſubſtance is of ſuch a nature, that it can
imbue the Solar light, and tranſmit the ſame through all its whole
depth, ſo as to be able to appear to us alwayes ſhining; and in this
manner Copernicus excuſeth the not changing figure in Venus: but
of her ſmall variation of Magnitude, he maketh no mention at all;

and much leſs of Mars than was needful; I believe as being
ble ſo well as he deſired to ſalve a Phænomenon ſo contrary to his
Hypotheſis, and yet being convinced by ſo many other occurrences
and reaſons he maintained, and held the ſame Hypotheſis to be true.
Beſides theſe things, to make the Planets, together with the Earth,
to move above the Sun as the Centre of their converſions, and the

Moon onely to break that order, and to have a motion by it ſelf
about the earth; and to make both her, the Earth, and the whole
Elementary Sphere, to move all together about the Sun in a year,
this ſeemeth to pervert the order of this Syſteme, which rendreth
it unlikely and falſe. Theſe are thoſe difficulties that make me
wonder how Aristarchus and Copernicus, who muſt needs have
ſerved them, not having been able for all that to ſalve them, have
yet notwithſtanding by other admirable occurrences been induced
1to conſide ſo much in that which reaſon dictated to them, as that
they have conſidently affirmed that the ſtructure of the Univerſe
could have no other figure than that which they deſigned to
ſelves. There are alſo ſeveral other very ſerious and curious doubts,
not ſo eaſie to be reſolved by the middle ſort of wits, but yet
netrated and declared by Coperninus, which we ſhall defer till by
and by, after we have anſwered to other objections that ſeem to
make againſt this opinion. Now coming to the declarations and
anſwers to thoſe three before named grand Objections, I ſay, that
the two firſt not onely contradict not the Copernican Syſteme, but

greatly and abſolutely favour it; For both Mars and Venus ſeems
unequal to themſelves, according to the proportions aſſigned; and
Venus under the Sun ſeemeth horned, and goeth changing figures
in it ſelf exactly like the Moon.
Mars makes an
hot aſſault upon the
Copernican
ſteme.
The
na of Venus appear
contrary to the
ſteme of
cus.
Another
culty raiſed by
nus againſt
nicus.
Venus, according
to Copernicus,
ther lucid in it
ſelf, or elſe of a
tranſparent
ſtance.
Copernicus
eth nothing of the
ſmall variation of
bigneſs in Venus
and in Mars.
The moon much
diſturbeth the
der of the other
Planets.
Anſwers to the
three first
ons againſt the
pernican Syſteme.
SAGR. But how came this to be concealed from Copernicus,
and revealed to you?
SALV. Theſe things cannot be comprehended, ſave onely by
the ſenſe of ſeeing, the which by nature was not granted to man
ſo perfect, as that it was able to attain to the diſcovery of ſuch
ferences; nay even the very inſtrument of ſight is an impediment
to it ſelf: But ſince that it hath pleaſed God in our age to
ſafe to humane ingenuity, ſo admirable an invention of perfecting
our ſight, by multiplying it four, ſix, ten, twenty, thirty, and
ty times, infinite objects, that either by reaſon of their diſtance, or
for their extream ſmallneſſe were inviſible unto us, have by help
of the Teleſcope been rendered viſible.
SAGR. But Venus and Mars are none of the objects inviſible
for their diſtance or ſmallneſſe, yea, we do diſcern them with our
bare natural ſight; why then do we not diſtinguiſh the differences
of their magnitudes and figures?
SALV. In this, the impediment of our very eye it ſelf hath a

great ſhare, as but even now I hinted, by which the reſplendent and
remote objects are not repreſented to us ſimple and pure; but gives
them us fringed with ſtrange and adventitious rayes, ſo long and
denſe, that their naked body ſheweth to us agrandized ten,
ty, an hundred, yea a thouſand times more than it would appear, if
the capillitious rayes were taken away.
Thereaſon whence
it happens that
nus and Mars do
not appear to vary
magnitude ſo much
as is requiſite.
SAGR. Now I remember that I have read ſomething on this
ſubject, I know not whether in the Solar Letters, or in the
giatore of our common Friend, but it would be very good, aſwell
for recalling it into my memory, as for the information of
cius, who it may be never ſaw thoſe writings, that you would
clare unto us more diſtinctly how this buſineſſe ſtands, the
ledge whereof I think to be very neceſſary for the aſſiſting of us to
underſtand that of which we now ſpeak.
1
SIMP. I muſt confeſſe that all that which Salviatus hath
ken is new unto me, for truth is, I never have had the curioſity to
read thoſe Books, nor have I hitherto given any great credit to
the Teleſcope newly introduced; rather treading in the ſteps of

ther Peripatetick Philoſophers my companions, I have thought
thoſe things to be fallacies and deluſions of the Chryſtals, which
others have ſo much admired for ſtupendious operations: and
therefore if I have hitherto been in an errour, I ſhall be glad to be
freed from it, and allured by theſe novelties already heard from
you, I ſhall the more attentively hearken to the reſt.
The operations of
the Teleſcope
counted fallacies by
the Peripateticks.
SALV. The confidence that theſe men have in their own
prehenſiveneſſe, is no leſs unreaſonable than the ſmall eſteem they
have of the judgment of others: yet its much that they ſhould
ſteem themſelves able to judge better of ſuch an inſtrument,
out ever having made trial of it, than thoſe who have made, and
daily do make a thouſand experiments of the ſame: But I pray
you, let us leave this kind of pertinacious men, whom we
not ſo much as tax without doing them too great honour. And

turning to our purpoſe, I ſay, that reſplendent objects, whether
it is that their light doth refract on the humidity that is upon the
pupils, or that it doth reflect on the edges of the eye-browes,
fuſing its reflex rayes upon the ſaid pupils, or whether it is for ſome
other reaſon, they do appear to our eye, as if they were environ'd
with new rayes, and therefore much bigger than their bodies
would repreſent themſelves to us, were they diveſted of thoſe

radiations. And this aggrandizement is made with a greater and
greater proportion, by how much thoſe lucid objects are leſſer and
leſſer; in the ſame manner for all the world, as if we ſhould
poſe that the augmentation of ſhining locks were v.g. four inches,
which addition being made about a circle that hath four inches
ameter would increaſe its appearance to nine times its former
neſſe: but---------
Shining objects
ſeem environed
with adventitious
rayes.
The reaſon why
luminous bodies
pear enlarged
much the more, by
how much they are
leſſer.
SIMP. I believe you would have ſaid three times; for adding
four inches to this ſide, and four inches to that ſide of the
ter of a circle, which is like wiſe four inches, its quantity is
by tripled, and not made nine times bigger.
SALV. A little more Geometry would do well, Simplicius.

True it is, that the diameter is tripled, but the ſuperficies, which is
that of which we ſpeak, increaſeth nine times: for you muſt know,
Simplicius, that the ſuperficies of circles are to one another, as
the ſquares of their diameters; and a circle that hath four inches
diameter is to another that hath twelve, as the ſquare of four to
the ſquare of twelve; that is, as 16. is to 144 and therefore it ſhall
be increaſed nine times, and not three; this, by way of
ment to Simplicius. And proceeding forwards, if we ſhould add
1the ſaid irradiation of four inches to a circle that hath but two
ches of diameter onely, the diameter of the irradiation or
land would be ten inches, and the ſuperficial content of the circle
would be to the area of the naked body, as 100. to 4. for thoſe
are the ſquares of 10. and of 2. the agrandizement would
fore be 25. times ſo much; and laſtly, the four inches of hair or
fringe, added to a ſmall circle of an inch in diameter, the ſame
would be increaſed 81. times; and ſo continually the
tions are made with a proportion greater and greater, according
as the real objects that increaſe, are leſſer and leſſer.
Superficial
gures encreaſing
proportion double to
their lines.
SAGR. The doubt which puzzled Simplicius never troubled
me, but certain other things indeed there are, of which I deſire
a more diſtinct underſtanding; and in particular, I would know
on what ground you affirm that the ſaid agrandizement is alwayes
equal in all viſible
Objects the more
vigorous they are
in light, the more
they do ſeem to
creaſe.
SALV. I have already declared the ſame in part, when I ſaid,
that onely lucid objects ſo increaſed, and not the obſcure; now I
adde what remaines, that of the reſplendent objects thoſe that are
of a more bright light, make the reflection greater and more
ſplendent upon our pupil; whereupon they ſeem to augment
much more than the leſſe lucid: and that I may no more inlarge
my ſelf upon this particular, come we to that which the true
ſtris of Astronomy, Experience, teacheth us. Let us this evening,
when the air is very obſcure, obſerve the ſtar of Jupiter; we
ſhall ſee it very glittering, and very great; let us afterwards look

through a tube, or elſe through a ſmall trunk, which clutching the
hand cloſe, and accoſting it to the eye, we lean between the palm
of the hands and the fingers, or elſe by an hole made with a ſmall
needle in a paper; and we ſhall ſee the ſaid ſtar diveſted of its
beams, but ſo ſmall, that we ſhall judge it leſſe, even than a
eth part of its great glittering light ſeen with the eye at liberty:
we may afterwards behold the Dog-ſtars beautiful and bigger than

any of the other fixed ſtars, which ſeemeth to the bare eye no
great matter leſſe than Jupiter; but taking from it, as before, the
irradiation, its Diſcus will ſhew ſo little, that it will not be
thought the twentieth part of that of Jupiter, nay, he that hath not
very good eyes, will very hardly diſcern it; from whence it may
be rationally inferred, that the ſaid ſtar, as having a much more
lively light than Jupiter, maketh its irradiation greater than
ter doth his. In the next place, as to the irradiation of the Sun
and Moon, it is as nothing, by means of their magnitude, which

poſſeſſeth of it ſelf alone ſo great a ſpace in our eye, that it
veth no place for the adventitious rayes; ſo that their faces ſeem
cloſe clipt, and terminate. We may aſſure our ſelves of the ſame
truth by another experiment which I have often made triall of;
1
we may aſſure our ſelves, I ſay, that bodies ſhining with moſt|
ly light do irradiate, or beam forth rayes more by far than thoſe
that are of a more languiſhing light. I have many times ſeen
piter and Venus together twenty or thirty degrees diſtant from the
Sun, and the air being very dark, Venus appeared eight or ten
times bigger than Jupiter, being both beheld by the eye at
ty; but being beheld afterwards with the Teleſcope, the Diſcus
of Jupiter diſcovered it ſelf to be four or more times greater than
that of Venus, but the vivacity of the ſplendour of Venus was
comparably bigger than the languiſhing light of Jupiter; which
was only becauſe of Jupiters being far from the Sun, and from us;
and Venus neer to us, and to the Sun. Theſe things premiſed, it
will not be difficult to comprehend, how Mars, when it is in
ſition to the Sun, and therefore neerer to the Earth by ſeven times,
and more, than it is towards the conjunction, cometh to appear
ſcarce four or five times bigger in that ſtate than in this, when as it
ſhould appear more than fifty times ſo much; of which the only
irradiation is the cauſe; for if we diveſt it of the adventitious
rayes, we ſhall find it exactly augmented with the due proportion:
but to take away the capillitious border, the Teleſcope is the beſt

and only means, which inlarging its Diſcus nine hundred or a
thouſand times, makes it to be ſeen naked and terminate, as that
of the Moon, and different from it ſelf in the two poſitions,

cording to its due proportions to an hair. Again, as to Venus,
that in its veſpertine conjunction, when it is below the Sun, ought
to ſhew almoſt fourty times bigger than in the other matutine
junction, and yet doth not appear ſo much as doubled; it
eth, beſides the effect of the irradiation, that it is horned; and its
creſcents, beſides that they are ſharp, they do receive the Suns light
obliquely, and therefore emit but a faint ſplendour; ſo that as
being little and weak, its irradiation becometh the leſſe ample
and vivacious, than when it appeareth to us with its Hemiſphere all
ſhining: but now the Teleſcope manifeſtly ſhews its hornes to
have been as terminate and diſtinct as thoſe of the Moon, and
appear, as it were, with a great circle, and in a proportion thoſe
well neer fourty times greater than its ſame Diſcus, at ſuch time
as it is ſuperiour to the Sun in its ultimate matutine apparition.
An eaſie
riment that
eth the increaſe in
the ſtars, by means
of the adventitious
rays.
Jupiter augments
leſſe than the
ſtar.
The Sun and
Moon increaſe
tle.
It is ſeen by
nifeſt experience,
that the more
ſplendid bodies do
much more
ate than the leſſe
lucid.
The Teleſcope
is the beſt means to
take away the
radiations of the
Stars.
Another ſecond
reaſon of the ſmall
apparent increaſe
of Venus.
SAGR. Oh, Nicholas Copernicus, how great would have been
thy joy to have ſeen this part of thy Syſteme, confirmed with ſo
manifeſt
Copernicus
ſwaded by reaſons
contrary to ſenſible
experiments.
SALV. Tis true. But how much leſſe the fame of his ſublime
wit amongſt the intelligent? when as it is ſeen, as I alſo ſaid before,
that he did conſtantly continue to affirm (being perſwaded thereto
by reaſon) that which ſenſible experiments ſeemed to contradict;
for I cannot ceaſe to wonder that he ſhould conſtantly perſiſt in
ſaying, that Venus revolveth about the Sun, and is more than ſix
1times farther from us at one time, than at another; and alſo
eth to be alwayes of an equal bigneſs, although it ought to ſhew
forty times bigger when neareſt to us, than when fartheſt off.
SAGR. But in Jupiter, Saturn and Mercury, I believe that
the differences of their apparent magnitudes, ſhould ſeem
ally to anſwer to their different diſtances.
SALV. In the two Superiour ones, I have made preciſe
ſervations yearly for this twenty two years laſt paſt: In Mercury

there can be no obſervation of moment made, by reaſon it
fers not it ſelf to be ſeen, ſave onely in its greateſt digrſſieons
from the Sun, in which its diſtances from the earth are inſenſibly
unequal, and thoſe differences conſequently not to be obſerved;
as alſo its mutations of figures which muſt abſolutely happen in
it, as in Venus. And if we do ſee it, it muſt of neceſſity appear
in form of a Semicircle, as Venus likewiſe doth in her greateſt
digreſſions; but its diſcus is ſo very ſmall, and its ſplendor ſo
very great, by reaſon of its vicinity to the Sun, that the virtue
of the Teleſcope doth not ſuffice to clip its treſſes or adventitious
rayes, ſo as to make them appear ſhaved round about. It

mains, that we remove that which ſeemed a great inconvenience
in the motion of the Earth, namely that all the Planets moving
about the Sun, it alone, not ſolitary as the reſt, but in company
with the Moon, and the whole Elementary Sphear, ſhould move
round about the Sun in a year; and that the ſaid Moon withal
ſhould move every moneth about the earth. Here it is neceſſary
once again to exclaim and extol the admirable perſpicacity of
pernicus, and withal to condole his misfortune, in that he is not
now alive in our dayes, when for removing of the ſeeming
ſurdity of the Earth and Moons motion in conſort we ſee
ter, as if it were another Earth, not in conſort with the Moon,
but accompanied by four Moons to rovolve about the Sun in 12.
years together, with what ever things the Orbs of the four
cæan Stars can contain within them.
Mercury
teth not of clear
obſervations.
The difficulties
removed that ariſe
from the Earths
moving about the
Sun, not ſolitarily,
but in conſort with
the Moon.
SALV. Why do you call the four jovial Planets, Moons?
SAGR. Such they would ſeem to be to one that ſtanding in

Jupiter ſhould behold them; for they are of themſelves dark, and
receive their light from the Sun, which is manifeſt from their
ing eclipſed, when they enter into the cone of Jupiters ſhadow:
and becauſe onely thoſe their Hemiſpheres, that look towards the
Sun are illuminated, to us that are without their Orbs, and
er to the Sun, they ſeem alwayes lucid, but to one that ſhould be
in Jupiter, they would ſhew all illuminated, at ſuch time as they
were in the upper parts of their circles; but in the parts
our, that is between Jupiter and the Sun, they would from
piter be obſerved to be horned; and in a word they would, to
1the obſervators ſtanding in Jupiter, make the ſelf ſame changes
of Figure, that to us upon the Earth, the Moon doth make. You
ſee now how theſe three things, which at ſirſt ſeémed diſſonant,
do admirably accord with the Copernican Syſteme. Here alſo by
the way may Simplicius ſee, with what probability one may
clude, that the Sun and not the Earth, is in the Centre of the
Planetary converſions. And ſince the Earth is now placed
mongſt mundane Bodies, that undoubtedly move about the Sun,
to wit, above Mercury and Venus, and below Saturn, Jupiter,
and Mars; ſhall it not be in like manner probable, and perhaps
neceſſary to grant, that it alſo moveth round?
The Medicean
Stars areas it were
four Moons about
Jupiter.
SIMP. Theſe accidents are ſo notable and conſpicuous, that
it is not poſſible, but that Ptolomy and others his Sectators, ſhould
have had knowledge of them, and having ſo, it is likewiſe
ſary, that they have found a way to render reaſons of ſuch, and
ſo ſenſible appearances that were ſufficient, and alſo congruous
and probable, ſeeing that they have for ſo long a time been
ceived by ſuch numbers of learned
The Principal
ſcope of
mers, is to give a
reaſon of
ances.
SALV. You argue very well; but you know that the principal
ſcope of Aſtronomers, is to render only reaſon for the appearances
in the Cæleſtial Bodies, and to them, and to the motions of the
Stars, to accomodate ſuch ſtructures and compoſitions of Circles,
that the motions following thoſe calculations, anſwer to the ſaid
appearances, little ſcrupling to admit of ſome exorbitances, that
indeed upon other accounts they would much ſtick at. And Co-

pernic us himſelf writes, that he had in his firſt ſtudies reſtored the
Science of Aſtronomy upon the very ſuppoſitions of Ptolomy, and
in ſuch manner corrected the motions of the Planets, that the
computations did very exactly agree with the Phænomena, and
the Phænomena with the ſupputations, in caſe that he took the
Planets ſeverally one by one. But he addeth, that in going
bout to put together all the ſtructures of the particular Fabricks,
there reſulted thence a Monſter and Chimæra, compoſed of
bers moſt diſproportionate to one another, and altogether
patible; So that although it ſatisfied an Aſtronomer meerly
rithmetical, yet did it not afford ſatisfaction or content to the

Aſtronomer Phyloſophical. And becauſe he very well
ſtood, that if one might ſalve the Cæleſtial appearances with falſe
aſſumptions in nature, it might with much more eaſe be done by
true ſuppoſitions, he ſet himſelf diligently to ſearch whether
ny amongſt the antient men of fame, had aſcribed to the World
any other ſtructure, than that commonly received by Ptolomy;
and finding that ſome Pythagoreans had in particular aſſigned
the Diurnal converſion to the Earth, and others the annual
tion alſo, he began to compare the appearances, and
1ties of the Planets motions, with theſe two new ſuppoſitions, all
which things jumpt exactly with his purpoſe; and ſeeing the whole
correſpond, with admirable facility to its parts, he imbraced this
new Syſteme, and it took up his reſt.
Copernicus
ſtored Aſtronomy
upon the
ous of Ptolomy:
What moved
pernicus to
bliſh his Syſteme.
SIMP. But what great exorbitancies are there in the
maick Syſteme, for which there are not greater to be found in this
of Copernicus?
SALV. In the Ptolomaick Hypotheſis there are diſeaſes, and in

the Copernican their cures. And firſt will not all the Sects of
Phyloſophers, account it a great inconvenience, that a body
turally moveable in circumgyration, ſhould move irregularly upon
its own Centre, and regularly upon another point? And yet
there are ſuch deformed motions as theſe in the Ptolomæan
theſis, but in the Copernican all move evenly about their own
Centres. In the Ptolomaick, it is neceſſary to aſſign to the
leſtial bodies, contrary motions, and to make them all to move,
from Eaſt to Weſt, and at the ſame time, from Weſt to Eaſt;
But in the Copernican, all the Cæleſtial revolutions are towards
one onely way, from Weſt to Eaſt. But what ſhall we ſay of
the apparent motion of the Planets, ſo irregular, that they not
ly go one while ſwift, and another while ſlow, but ſometimes
wholly ſeace to move; and then after a long time return back
gain? To ſalve which appearances Ptolomie introduceth very great
Epicicles, accommodating them one by one to each Planet, with
ſome rules of incongruous motions, which are all with one
gle motion of the Earth taken away. And would not you,
plicius, call it a great abſurditie, if in the Ptolomaick
ſis, in which the particular Planets, have their peculiar Orbs
ſigned them one above another, one muſt be frequently forced
to ſay, that Mars, conſtituted above the Sphære of the Sun, doth
ſo deſcend, that breaking the Solar Orb, it goeth under it, and
approacheth neaer to the Earth, than to the Body of the Sun,
and by and by immeaſurably aſcendeth above the ſame? And
yet this, and other exorbitancies are remedied by the Soul and
fingle annual motion of the Earth.
Inconveniencies
that are in the
ſteme of Ptolomy.
SAGR. I would gladly be bettter informed how theſe ſtations,
and retrograde and direct motions, which did ever ſeem to me
great improbalities, do accord in this Copernican
Its a great
gument in favour
of Copernicus, that
he obviates the
tions &
tions of the motions
of the Planets.
SALV. You ſhall ſee them ſo to accord, Sagredus, that
this onely conjecture ought to be ſufficient to make one that
is not more than pertinacious or ſtupid, yield, aſſent to all the
reſt of this Doctrine. I tell you therefore, that nothing being
altered in the motion of Saturn, which is 30 years, in that
of Jupiter, which is 12, in that of Mars, which is 2, in that of
Venus, which is 9. moneths, in that of Mercury, which is 80.
1dayes, or thereabouts, the ſole annual motion of the Earth
tween Mars and Venus, cauſeth the apparent inequalities in all

the five ſtars before named. And for a facile and full
ſtanding of the whole, I will deſcribe this figure of it.
fore ſuppoſe the Sun to be placed in the centre O, about which
we will draw the Orb deſcribed by the Earth, with the
nual motion B G M, and let the circle deſcribed, v. gr. by
Jupiter about the Sun in 12. years, be this BGM, and in the
19[Figure 19]

ſtarry ſphere let us imagine the Zodiack Y V S. Again, in the
annual Orb of the Earth let us take certain equal arches, B C,
C D, E F, F G, G H, H I, I K, K L, L M, and in the Sphere
of Jupiter let us make certain other arches, paſſed in the ſame
times in which the Earth paſſeth hers, which let be B C, C D,
D E, E F, F G, G H, H I, I K, K L, L M, which ſhall each be
proportionally leſſe than theſe marked in the Earths Orb, like
as the motion of Jupiter under the Zodiack is ſlower than the
annual. Suppoſing now, that when the Earth is in B, Jupiter is
in B, it ſhall appear to us in the Zodiack to be in P, deſcribing
1the right line B B P. Next ſuppoſe the Earth to be moved from
B to C, and Jupiter from B to C, in the ſame time; Iupiter
ſhall appear to have paſſed in the Zodiack to Q, and to have
moved ſtraight forwards, according to the order of the ſignes
P que In the next place, the Earth paſſing to D, and Iupiter
to D, it ſhall be ſeen in the Zodiack in R, and from E,
ter being come to E; will appear in the Zodiack in S, having
all this while moved right forwards. But the Earth afterwards
beginning to interpoſe more directly between Iupiter and the
Sun, ſhe being come to F, and Iupiter to F, he will appear in
T, to have already begun to return apparently back again
der the Zodiack, and in that time that the Earth ſhall have
ed the arch E F, Iupiter ſhall have entertained himſelf between
the points S T, and ſhall have appeared to us almoſt
leſſe and ſtationary. The Earth being afterwards come to G,
and Iupiter to G, in oppoſition to the Sun, it ſhall be viſible in
the Zodiack at V, and much returned backwards by all the arch
of the Zodiack T V; howbeit that all the way purſuing its even
courſe it hath really gone forwards not onely in its own circle,
but in the Zodiack alſo in reſpect to the centre of the ſaid
ack, and to the Sun placed in the ſame. The Earth and Iupiter
again continuing their motions, when the Earth is come to H,
and Iupiter to H, it ſhall ſeem very much gone backward in the
Zodiack by all the arch V X. The Earth being come to I, and
Iupiter to I, it ſhall be apparently moved in the Zodiack by the
tle ſpace X Y, and there it will ſeem ſtationary. When
wards the Earth ſhall be come to K, and Iupiter to K; in the
Zodiack he ſhall have paſſed the arch Y N in a direct motion;
and the Earth purſuing its courſe to L, ſhall ſee Iupiter in L, in
the point Z. And laſtly Iupiter in M ſhall be ſeen from the Earth
M, to have paſſed to A, with a motion ſtill right forwards; and
its whole apparent retrogadation in the Zodiack ſhall anſwer to
the arch S Y, made by Iupiter, whilſt that he in his own circle
paſſeth the arch E I, and the Earth in hers the arch E I. And

this which hath been ſaid, is intended of Saturn and of Mars
alſo; and in Saturn thoſe retrogradations are ſomewhat more
frequent than in Jupiter, by reaſon that its motion is a little
ſlower than that of Jupiter, ſo that the Earth overtaketh it
it in a ſhorter ſpace of time; in Mars again they are more
rare, for that its motion is more ſwift than that of Jupiter.
Whereupon the Earth conſumeth more time in recovering it. Next
as to Venus and Mercury, whoſe Circles are comprehended by that

of the Earth, their ſtations and regreſſions appear to be
oned, not by their motions that really are ſuch, but by the anual
motion of the ſaid Earth, as Copernicus exellently demonſtrateth,
1together with Appollonius Pergæus in lib. 5. of his Revolutions,
Chap. 35.
The ſole annual
motion of the
Earth cauſeth
great inequality of
motions in the five
Planets.
A demonſtration of
the inequalities of
the three ſuperiour
Planets dependent
on the annual
tion of the Earth.
Retrogradations
more frequent in
Saturn, leſſe in
piter, and yet leſſe
in Mars, and why.
The
tion of Venus and
Mercury
ſtrated by
nius and
cus.
You ſee, Gentlemen, with what facility and ſimplicity the

al motion, were it appertaining to the Earth, is accommodated
to render a reaſon of the apparent exorbitances, that are obſerved
in the motions of the five Planets, Saturn, Jupiter, Mars,
nus and Mercury, taking them all away, and reducing them to

equal and regular motions. And of this admirable effect,
cholas Copernicus, hath been the firſt that hath made the reaſon
plain unto us. But of another effect, no leſſe admirable than
this, and that with a knot, perhaps more difficult to unknit,
bindeth the wit of man, to admit this annual converſion, and to
leave it to our Terreſtrial Globe; a new and unthought of
jecture ariſeth from the Sun it ſelf, which ſheweth that it is
ling to be ſingular in ſhifting, of this atteſtation of ſo eminent a
concluſion, rather as a teſtimony beyond all exception, it hath
deſired to be heard apart. Hearken then to this great and new

The annual
tion of the Earth
moſt apt to render
a reaſon of the
orbttances of the
five Planets.
The Sun it ſelf
teſtifieth the
al motion to belong
to the Earth.
The Lyncæan
Academick the
firſt diſcoverer of
the Solar ſpots, and
all the other
ſtial novelties.
The firſt diſcoverer and obſerver of the Solar ſpots, as alſo of
all the other Cœleſtial novelties, was our Academick Lincæus; and
he diſcovered them anno 1610. being at that time Reader of the
Mathematicks, in the Colledge of Padua, and there, and in
nice, he diſcourſed thereof with ſeveral perſons, of which ſome

are yet living: And the year following, he ſhewed them in Rome
to many great perſonages, as he relates in the firſt of his Letters
to Marcus Velſerus, ^{*} Sheriffe of Auguſta. He was the
firſt that againſt the opinions of the too timorous and too jealous

aſſertors of the Heavens inalterability, affirmed thoſe ſpots to be
matters, that in ſhort times were produced and diſſolved: for as
to place, they were contiguous to the body of the Sun, and
volved about the ſame; or elſe being carried about by the ſaid
Solar body, which revolveth in it ſelfe about its own Centre, in
the ſpace almoſt of a moneth, do finiſh their courſe in that time;
which motion he judged at firſt to have been made by the Sun
bout an Axis erected upon the plane of the Ecliptick; in regard
that the arches deſcribed by the ſaid ſpots upon the Diſcus of the
Sun appear unto our eye right lines, and parallels to the plane of
the Ecliptick: which therefore come to be altered, in part, with
ſome accidental, wandring, and irregular motions, to which they
are ſubject, and whereby tumultuarily, and without any order
they ſucceſſively change ſituations amongſt themſelves, one
while crouding cloſe together, another while diſſevering, and
ſome dividing themſelves into many and very much changing
gures, which, for the moſt part, are very unuſual. And albeit
thoſe ſo inconſtant mutations did ſomewhat alter the primary
1riodick courſe of the ſaid ſpots, yet did they not alter the
on of our friend, ſo as to make him believe, that they were any
eſſential and fixed cauſe of thoſe deviations, but he continued to
hold, that all the apparent alterations derived themſelves from
thoſe accidental mutations: in like manner, juſt as it would
pen to one that ſhould from far diſtant Regions obſerve the
tion of our Clouds; which would be diſcovered to move with a
moſt ſwift, great, and conſtant motion, carried round by the
urnal Vertigo of the Earth (if haply that motion belong to the
ſame) in twenty four hours, by circles parallel to the
al, but yet altered, in part, by the accidental motions cauſed by
the winds, which drive them, at all adventures, towards different
quarters of the World. While this was in agitation, it came to
paſs that Velſerus ſent him two Letters, written by a certain

ſon, under the feigned name of ^{*} Apelles, upon the ſubject of
theſe Spots, requeſting him, with importunity, to declare his
thoughts freely upon thoſe Letters, and withall to let him know
what his opinion was touching the eſſence of thoſe ſpots; which his
requeſt he ſatisfied in 3 Letters, ſhewing firſt of all howvain the
conjectures of Apelles were; & diſcovering, ſecondly, his own
nions; withal foretelling to him, that Apelles would undoubtedly
be better adviſed in time, and turn to his opinion, as it afterwards
came to paſs. And becauſe that our Academian (as it was alſo
the judgment of many others that were intelligent in Natures
crets) thought he had in thoſe three Letters inveſtigated and
monſtrated, if not all that could be deſired, or required by
mane curioſity, at leaſt all that could be attained by humane
reaſon in ſuch a matter, he, for ſome time (being buſied in other
ſtudies) intermitted his continual obſervations, and onely in
placency to ſome friend, joyned with him, in making now and
then an abrupt obſervation: till that he, and after ſome years,

we, being then at my ^{*} Country-ſeat, met with one of the
ry Solar ſpots very big, and thick, invited withal by a clear and
conſtant ſerenity of the Heavens, he, at my requeſt, made
vations of the whole progreſſe of the ſaid ſpot, carefully marking
upon a ſheet of paper the places that it was in every day at the
time of the Suns coming into the Meridian; and we having found
that its courſe was not in a right line, but ſomewhat incurvated,
we came to reſolve, at laſt, to make other obſervations from time
to time; to which undertaking we were ſtrongly induced by a
conceit, that accidentally came into the minde of my Gueſt,
which he imparted to me in theſe or the like words.
The hiſtory of
the proceedings of
the Academian
for a long time
bout the
on of the Solar
ſpots.
* Duumviro.
* This Authors
true name is
ſtopher Scheiner us
a Jeſuit, and his
Book here meant
is intituled,
les poſt tabulam.
* La mia villa
delle Selue.
In my opinion, Philip, there is a way opened to a buſineſs of
very great conſequence. For if the Axis about which the Sun
turneth be not erect perpendicularly to the plane of the
1
tick, but is inclined upon the ſame, as its crooked courſe, but
ven now obſerved, makes me believe, we ſhall be able to make
ſuch conjectures of the ſtates of the Sun and Earth, as neither ſo
ſolid or ſo rational have been hitherto deduced from any other
cident whatſoever. I being awakened at ſo great a promiſe,
portun'd him to make a free diſcovery of his conceit unto me.
And he continued his diſcourſe to this purpoſe. If the Earths

motion were along the Ecliptique about the Sun; and the Sun
were conſtituted in the centre of the ſaid Ecliptick, and therein
revolved in its ſelf, not about the Axis of the ſaid Ecliptique
(which would be the Axis of the Earths annual motion) but
on one inclined, it muſt needs follow, that ſtrange changes will
repreſent themſelves to us in the apparent motions of the Solar
ſpots, although the ſaid Axis of the Sun ſhould be ſuppoſed to
perſiſt perpetually and immutably in the ſame inclination, and in
one and the ſame direction towards the ſelf-ſame point of the
Univerſe. Therefore the Terreſtrial Globe in the annual motion
moving round it, it will firſt follow, that to us, carried about by
the ſame, the courſes of the ſpots ſhall ſometimes ſeem to be
made in right lines, but this only twice a year, and at all other
times ſhall appear to be made by arches inſenſibly incurvated.
Secondly, the curvity of thoſe arches for one half of the year,
will ſhew inclined the contrary way to what they will appear in
the other half; that is, for ſix moneths the convexity of the
ches ſhall be towards the upper part of the Solar Diſcus, and for
the other ſix moneths towards the inferiour. Thirdly, the ſpots
ginning to appear, and (if I may ſo ſpeak) to riſe to our eye from
the left ſide of the Solar Diſcus, and going to hide themſelves
and to ſet in the right ſide, the Oriental termes, that is, of their
firſt appearings for ſix moneths, ſhall be lower than the oppoſite
termes of their occultations; and for other ſix moneths it ſhall
happen contrarily, to wit, that the ſaid ſpots riſing from more
levated points, and from them deſcending, they ſhall, in their
courſes, go and hide themſelves in lower points; and onely for
two dayes in all the year ſhall thoſe termes of riſings and
tings be equilibrated: after which freely beginning by ſmall
grees the inclination of the courſes of the ſpots, and day by day
growing bigger, in three moneths, it ſhall arrive at its greateſt
obliquity, and from thence beginning to diminiſh, in ſuch another
time it ſhall reduce it ſelf to the other Æquilibrium. It ſhall
pen, for a fourth wonder, that the courſe of the greateſt
quity ſhall be the ſame with the courſe made by the right line,
and in the day of the Libration the arch of the courſe ſhall ſeem
more than ever incurvated. Again, in the other times,
ing as the pendency ſhall ſucceſſively diminiſh, and make its
1proach towards the Æquilibrium, the incurvation of the arches
of the courſes on the contrary ſhall, by degrees, increaſe.
A concipt that
came ſuddenly
to the minde of
the Academian
Lyncæus
ing the great
ſequence that
lowed upon the
tion of the Solar
ſpots.
Extravagant
tations to be
ved in the motions
of the ſpots,
ſeen by the
demick, in caſe
the Earth had the
annual motion.
SAGR. I confeſſe, Salviatus, that to interrupt you in your
Diſcourſe is ill manners, but I eſteem it no leſſe rudeneſs to
mit you to run on any farther in words, whilſt they are, as the
ſaying is, caſt into the air: for, to ſpeak freely, I know not how
to form any diſtinct conceit of ſo much as one of theſe
ons, that you have pronounced; but becauſe, as I thus
ly and confuſedly apprehend them, they hold forth things of
mirable conſequence, I would gladly, ſome way or other, be
made to underſtand the ſame.
SALV. The ſame that befalls you, befell me alſo, whilſt my
Gueſt tranſported me with bare words; who afterwards aſſiſted
my capacity, by deſcribing the buſineſſe upon a material

ment, which was no other than a ſimple Sphere, making uſe of
ſome of its circles, but to a different purpoſe from that, to which
they are commonly applied. Now I will ſupply the defect of
the Sphere, by drawing the ſame upon a piece of paper, as need
ſhall require. And to repreſent the firſt accident by me
ded, which was, that the courſes or journeys of the ſpots, twice
a year, and no more, might be ſeen to be made in right lines, let
us ſuppoſe this point O [in Fig. 4.] to be the centre of the grand
Orb, or, if you will, of the Ecliptick, and likewiſe alſo of the
Globe of the Sun it ſelf; of which, by reaſon of the great
ſtance that is between it and the Earth, we that live upon the
Earth, may ſuppoſe that we ſee the one half: we will therefore
deſcribe this circle A B C D about the ſaid centre O, which
ſenteth unto us the extream term that divideth and ſeparates the
Hemiſphere of the Sun that is apparent to us, from the other that
is occult. And becauſe that our eye, no leſſe than the centre of
the Earth, is underſtood to be in the plane of the Ecliptick, in
which is likewiſe the centre of the Sun, therefore, if we ſhould
fancy to our ſelves the body of the Sun to be cut thorow by the
ſaid plane, the ſection will appear to our eye a right line, which
let be B O D, and upon that a perpendicular being let fall AOC,
it ſhall be the Axis of the ſaid Ecliptick, and of the annual
tion of the Terreſtrial Globe. Let us next ſuppoſe the Solar body
(without changing centre) to revolve in it ſelf, not about the
Axis A O C (which is the erect Axis upon the plane of the
cliptick) but about one ſomewhat inclined, which let be this
E O I, the which fixed and unchangeable Axis maintaineth it ſelf
perpetually in the ſame inclination and direction towards the
ſame points of the Firmament, and of the Univerſe. And
cauſe, in the revolutions of the Solar Globe, each point of its
perficies (the Poles excepted) deſcribeth the circumference of a
1circle, either bigger or leſſer, according as it is more or leſſe
mote from the ſaid Poles, let us take the point F, equally diſtant
from them, and draw the diameter F O G, which ſhall be
dicular to the Axis E I, and ſhall be the diameter of the grand
circle deſcribed about the Poles E I. Suppoſing not that the
Earth, and we with her be in ſuch a place of the Ecliptick, that
the Hemiſphere of the Sun to us apparent is determin'd or
ed by the circle A B C D, which paſſing (as it alwayes doth) by
the Poles A C, paſſeth alſo by E I. It is manifeſt, that the grand
circle, whoſe diameter is FG, ſhall be erect to the circle A B C D,
to which the ray that from our eye falleth upon the centre O, is
perpendicular; ſo that the ſaid ray falleth upon the plane of
the circle, whoſe diameter is F G, and therefore its circumference
will appear to us a right line, and the ſelf ſame with F G,
upon if there ſhould be in the point F, a ſpot, it comming
wards to be carried about by the Solar converſion, would, upon
the ſurface of the Sun, trace out the circumference of that
cle, which ſeems to us a right line. Its courſe or paſſage will
therefore ſeem ſtraight. And ſtraight alſo will the motion of the
other ſpots appear, which in the ſaid revolution ſhall deſcribe
ſer circles, as being all parallel to the greater, and to our eye
placed at an immenſe diſtance from them. Now, if you do but
conſider, how that after the Earth ſhall in ſix moneths have run
thorow half the grand Orb, and ſhall be ſituate oppoſite to that
Hemiſphere of the Sun, which is now occult unto us, ſo as that
the boundary of the part that then ſhall be ſeen, may be the ſelf
ſame A B C D, which alſo ſhall paſſe by the Poles E I; you
ſhall underſtand that the ſame will evene in the courſes of the
ſpots, as before, to wit, that all will appear to be made by right
lines. But becauſe that that accident takes not place, ſave
ly when the terminator or boundary paſſeth by the Poles E I,
and the ſaid terminator from moment to moment, by meanes of
the Earths annual motion, continually altereth, therefore its
ſage by the fixed Poles E I, ſhall be momentary, and
ly momentary ſhall be the time, in which the motions of thoſe
ſpots ſhall appear ſtraight. From what hath been hitherto ſpoken
one may comprehend alſo how that the apparition and beginning
of the motion of the ſpots from the part F, proceeding towards
G, their paſſages or courſes are from the left hand, aſcending
wards the right; but the Earth being placed in the part
trically oppoſite the appearance of the ſpots about G, ſhall ſtill
be to the left hand of the beholder, but the paſſage ſhall be
cending towards the right hand F. Let us now deſcribe the Earth
te be ſituate one fourth part farther diſtant from its preſent ſtate,
and let us draw, as in the other figure, the terminator A B C D,
1[as in Fig. 5.] and the Axis, as before A C, by which the plane
of our Meridian would paſſe, in which plane ſhould alſo be the
Axis of the Suns revolution, with its Poles, one towards us, that
is, in the apparent Hemiſphere, which Pole we will repreſent by
the point E, and the other ſhall fall in the occult Hemiſphere,
and I mark it I. Inclining therefore the Axis E I, with the
riour part E, towards us, the great circle deſcribed by the Suns
converſion, ſhall be this B F D G, whoſe half by us ſeen,
ly B F D, ſhall no longer ſeem unto us a right line, by reaſon the
Poles E I are not in the circumference A B C D, but ſhall appear
incurvated, and with its convexity towards the inferiour part C.
And it is manifeſt, that the ſame will appear in all the leſſer
cles parallel to the ſame B F D. It is to be underſtood alſo, that
when the Earth ſhall be diametrically oppoſite to this ſtate, ſo
that it ſeeth the other Hemiſphere of the Sun, which now is hid,
it ſhall of the ſaid great circle behold the part D G B incurved,
with its convexity towards the ſuperiour part A; and the
ſes of the ſpots in theſe conſtitutions ſhall be firſt, by the arch
B F D, and afterwards by the other D G B, and the firſt
tions and ultimate occultations made about the points B and D,
ſhall be equilibrated, and not thoſe that are more or leſſe
ted than theſe. But if we conſtitute the Earth in ſuch a place
of the Ecliptick, that neither the boundary A B C D, nor the
Meridian A C, paſſeth by the Poles of the Axis E I, as I will ſhew
you anon, drawing this other Figure [viz. Fig. 6.] wherein the
apparent or viſible Pole E falleth between the arch of the
nator A B, and the ſection of the Meridian A C; the diameter
of the great circle ſhall be F O G, and the apparent ſemicircle
F N G, and the occult ſemicircle G S F, the one incurvated with
its convexity N towards the inferiour part, and the other alſo
bending with its convexity S towards the upper part of the Sun.
The ingreſſions and exitions of the ſpots, that is, the termes F
and G ſhall not be librated, as the two others B and D; but F
ſhall be lower, and G higher: but yet with leſſer difference
than in the firſt Figure. The arch alſo F N G ſhall be
ted, but not ſo much as the precedent B F D; ſo that in this
ſition the paſſages or motions of the ſpots ſhall be aſcendent
from the left ſide F, towards the right G, and ſhall be made by
curved lines. And imagining the Earth to be conſtituted in the
poſition diametrically oppoſite; ſo that the Hemiſphere of the
Sun, which was before the occult, may be the apparent, and
minated by the ſame boundary A B C D, it will be manifeſtly
diſcerned, that the courſe of the ſpots ſhall be by the arch G S F,
beginning from the upper point G, which ſhall then be likewiſe
from the left hand of the beholder, and going to determine,
1ſcending towards the right, in the point F. What I have
therto ſaid, being underſtood, I believe that there remains no
difficulty in conceiving how ſrom the paſſing of the terminator of
the Solar Hemiſpheres by the Poles of the Suns converſion, or
neer or far from the ſame, do ariſe all the differences in the
rent courſes of the ſpots; ſo that by how much the more thoſe Poles
ſhall be remote from the ſaid terminator, by ſo much the more ſhall
thoſe courſes be incurvated, and leſſe oblique; whereupon at
the ſame diſtance, that is, when thoſe Poles are in the ſection of
the Meridian, the incurvation is reduced to the greateſt, but the
obliquity to the leaſt, that is to Æquilibrium, as the ſecond of
theſe three laſt figures [viz. Fig. 5.] demonſtrateth. On the
contrary, when the Poles are in the terminator, as the firſt of
theſe three figures [viz. Fig. 4.] ſheweth the inclination is at
the greateſt, but the incurvation at the leaſt, and reduced to
rectitude. The terminator departing from the Poles, the curvity
begins to grow ſenſible, the obliquity all the way encreaſing,
and the inclination growing leſſer.
The firſt
cident to be
ved in the motion
of the Solar ſpots;
and conſequently
all the reſt
ned.
Theſe are thoſe admirable and extravagant mutations, that my
Gueſt told me would from time to time appear in the progreſſes
of the Solar ſpots, if ſo be it ſhould be true that the annual
tion belonged to the Earth, and that the Sun being conſtituted
in the centre of the Ecliptick, were revolved in it ſelf upon an
Axis, not erect, but inclined to the Plane of the ſaid
tick.
SAGR. I do now very well apprehend theſe conſequences,
and believe that they will be better imprinted in my fancy, when
I ſhall come to reflect upon them, accommodating a Globe to
thoſe inclinations, and then beholding them from ſeveral
ces. It now remains that you tell us what followed afterwards
touching the event of theſe imaginary
The events
ing obſerved, were
anſwerable to the
predictions.
SALV. It came to paſſe thereupon, that continuing many
veral moneths to make moſt accurate obſervations, noting down
with great exactneſſe the courſes or tranſitions of ſundry ſpots at
divers times of the year, we found the events punctually to
reſpond to the predictions.
SAGR. Simplicius, if this which Salviatus ſaith be true; (nor
can we diſtruſt him upon his word) the Ptolomeans and
teleans hadneed of ſolid arguments, ſtrong conjectures, and
well grounded experiments to counterpoiſe an objection of ſo
much weight, and to ſupport their opinion from its final
throw.
SIMP. Fair and ſoftly good Sir, for haply you may not yet
be got ſo far as you perſwade your ſelf you are gone. And
though I am not an abſolute maſter of the ſubject of that
1tion given us by Salviatus; yet do I not find that my Logick,

whilſt I have a regard to form, teacheth me, that that kind of
gumentation affords me any neceſſary reaſon to conclude in
vour of the Copernican Hypotheſis, that is, of the ſtability of
the Sun in the centre of the Zodiack, and of the mobility of
the Earth under its circumference. For although it be true, that
the ſaid converſion of the Sun, and cirnition of the Earth being
granted, there be a neceſſity of diſcerning ſuch and ſuch ſtrange
extravagancies as theſe in the ſpots of the Sun, yet doth it not
follow that arguing per converſum, from finding ſuch like
uſual accidents in the Sun, one muſt of necſſity conclude the
Earth to move by the circumference, and the Sun to be placed
in the centre of the Zodiack. For who ſhall aſſertain me that the
like irregularities may not as well be viſible in the Sun, it being
moveable by the Ecliptick, to the inhabitants of the Earth, it
being alſo immoveable in the centre of the ſame? Unleſſe you
demonſtrate to me, that there can be no reaſon given for that
pearance, when the Sun is made moveable, and the Earth ſtable,
I will not alter my opinion and belief that the Sun moveth, and
the Earth ſtandeth ſtill.
Though the
nual motion
ed to the Earth
ſwerth to the
nomena of the
lar ſpots, yet doth
it not follow by
verſion that from
the Phænomena of
the ſpots one may
infor the annual
motion to belong to
the Earth.
SAGR. Simplicius behaveth himſelf very bravely, and argueth
very ſubtilly in defence of the cauſe of Ariſtotle and Ptolomy;
and if I may ſpeak the truth, mythinks that the converſation of
Salviatus, though it have been but of ſmall continuance, hath
much farthered him in diſcourſing ſilogiſtically. An effect which
I know to be wrought in others as well as him. But as to finding
and judging whether competent reaſon may be rendered of the
apparent exorbitancies and irregularities in the motions of the
ſpots, ſuppoſing the Earth to be immoveable, and the Sun
moveable, I ſhall expect that Salviatus manifeſt his opinion to
us, for it is very probable that he he hath conſidered of the
ſame, and collected together whatever may be ſaid upon the
point.
SALV. I have often thought thereon, and alſo diſcourſed
thereof with my Friend and Gueſt afore-named; and touching
what is to be produced by Philoſophers and Aſtronomers, in
fence of the ancient Syſteme, we are on one hand certain,
tain I ſay, that the true and pure Peripateticks laughing at ſuch

as employ themſelves in ſuch, to their thinking, inſipid
ries, will cenſure all theſe Phænomena to be vain illuſions of the
Chriſtals; and in this manner will with little trouble free
ſelves from the obligation of ſtudying any more upon the ſame.
Again, as to the Aſtronomical Philoſophers, after we have with
ſome diligence weighed that which may be alledged as a mean
between thoſe two others, we have not been able to find out an
1anſwer that ſufficeth to ſatisſie at once the courſe of the ſpots,
and the diſcourſe of the Mind. I will explain unto you ſo much
as I remember thereof, that ſo you may judge thereon as ſeems
beſt unto you.
The Pure
patetick
phers will laugh at
the ſpots and their
Phænomena, as
illuſions of the
Chryſtals in the
Teleſcope.
Suppoſing that the apparent motions of the Solar ſpots are the
ſame with thoſe that have been above declared, and ſuppoſing the
Earth to be immoveable in the centre of the Ecliptick, in whoſe
circumference let the center of the Sun be placed; it is neceſſary
that of all the differences that are ſeen in thoſe motions, the
ſes do reſide in the motions that are in the body of the Sun:
Which in the firſt place muſt neceſſarily revolve in it ſelf (i. e.

about its own axis) carrying the ſpots along therewith; which
ſpots have been ſuppoſed, yea and proved to adhere to the
lar ſuperficies. It muſt ſecondly be confeſt, that the Axis of the
Solar converſion is not parallel to the Axis of the Ecliptick, that
is as much as to ſay, that it is not perpendicularly erected upon
the Plane of the Ecliptick, becauſe if it were ſo, the courſes and
exitions of thoſe ſpots would ſeem to be made by right lines
rallel to the Ecliptick. The ſaid Axis therefore is inclining, in
regard the ſaid courſes are for the moſt part made by curve lines.
It will be neceſſary in the third place to grant that the
on of this Axis is not fixed, and continually extended towards
one and the ſame point of the Univerſe, but rather that it doth
alwayes from moment to moment go changing its direction; for
if the pendency ſhould always look towards the ſelf ſame point,
the courſes of the ſpots would never change appearance; but
appearing at one time either right or curved, bending upwards
or downwards, aſcending or deſcending, they would appear
the ſame at all times. It is therefore neceſſary to ſay, that the
ſaid Axis is convertible; and is ſometimes found to be in the
Plane of the circle that is extreme, terminate, or of the viſible
Hemiſphere, I mean at ſuch time as the courſes of the ſpots
ſeem to be made in right lines, and more than ever pendent,
which happeneth twice a year; and at other times found to be in
the Plane of the Meridian of the Obſervator, in ſuch ſort that
one of its Poles falleth in the viſible Hemiſphere of the Sun, and
the other in the occult; and both of them remote from the
treme points, or we may ſay, from the poles of another Axis of
the Sun, which is parallel to the Axis of the Ecliptick; (which
ſecond Axis muſt neceſſarily be aſſigned to the Solar Globe)
mote, I ſay, as far as the inclination of the Axis of the revolution
of the ſpots doth import; and moreover that the Pole falling in
the apparent Hemiſphere, is one while in the ſuperiour, another
while in the inferiour part thereof; for that it muſt be ſo, the
courſes themſelves do manifeſtly evince at ſuch time as they are
1equilibrated, and in their greateſt curvity, one while with
their convexity towards the upper part, and another while
towards the lower part of the Solar Diſcus. And becauſe
thoſe poſitions are in continuall alteration, making the
clinations and incurvations now greater, now leſſer, and
times reduce themſelves, the firſt ſort to perfect libration, and
the ſecond to perfect perpendicularity, it is neceſſary to aſſert that
the ſelf ſame Axis of the monethly revolution of the ſpots hath
a particular revolution of its own, whereby its Poles deſcribe
two circles about the Poles of another Axis, which for that
ſon ought (as I have ſaid) to be aſſigned to the Sun, the
ameter of which circles anſwereth to the quantity of the
nation of the ſaid Axis. And it is neceſſary, that the time of its
Period be a year; for that ſuch is the time in which all the
pearances and differences in the courſes of the ſpots do return.
And that the revolution of this Axis, is made about the Poles of
the other Axis parallel to that of the Ecliptick, & not about other
points, the greateſt inclinations and greateſt incurvations, which
are always of the ſame bigneſs, do clearly prove. So that finally, to
maintain the Earth fixed in the centre, it will be neceſſary to
ſign to the Sun, two motions about its own centre, upon two
ral Axes, one of which finiſheth its converſion in a year, and the
other in leſſe than a moneth; which aſſumption ſeemeth, to my
underſtanding, very hard, and almoſt impoſſible; and this
pendeth on the neceſſity of aſcribing to the ſaid Solar body two
other motions about the Earth upon different Axes, deſcribing
with one the Ecliptick in a year, and with the other forming
rals, or circles parallel to the Equinoctial one every day:
whereupon that third motion which ought to be aſſigned to the
Solar Clobe about its own centre (I mean not that almoſt
monethly, which carrieth the ſpots about, but I ſpeak of that
ther which ought to paſſe thorow the Axis and Poles of this
monethly one) ought not, for any reaſon that I ſee, to finiſh its
Period rather in a year, as depending on the annual motion by
the Ecliptick, than in twenty four hours, as depending on the
diurnal motion upon the Poles of the Equinoctial. I know, that
what I now ſpeak is very obſcure, but I ſhall make it plain unto
you, when we come to ſpeak of the third motion annual,
ed by Copernicus, to the Earth. Now if theſe four motions, ſo
incongruous with each other, (all which it would be neceſſary to
aſſign to the ſelf ſame body of the Sun) may be reduced to one
ſole and ſimple motion, aſſigned the Sun upon an Axis that never
changeth poſition, and that without innovating any thing in the
motions for ſo many other cauſes aſſigned to the Terreſtrial
Globe, may ſo eaſily ſalve ſo many extravagant appearances in
1the motions of the Solar ſpots, it ſeemeth really that ſuch an
Hypotheſis ought not to be rejected.
If the Earth be
immoveable in the
centre of the
ack, there muſt be
aſcribed to the Sun
four ſeveral
ons, as is declared
at length.
This, Simplicius, is all that came into the minds of our friend,
and my ſelf, that could be alledged in explanation of this
menon by the Copernicans, and by the Ptolomæans, in defence
of their opinions. Do you inferre from thence what your
ment perſwades you.
SIMP. I acknowledge my ſelf unable to interpoſe in ſo
portant a deciſion: And, as to my particular thoughts, I will
ſtand neutral; and yet nevertheleſſe I hope that a time will
come, when our minds being illumin'd by more lofty
tions than theſe our humane reaſonings, we ſhall be awakened
and freed from that miſt which now is ſo great an hinderance to
our ſight.
SAGR. Excellent and pious is the counſel taken by
cius, and worthy to be entertained and followed by all, as that
which being derived from the higheſt wiſdome and ſupreameſt
authority, may onely, with ſecurity be received. But yet ſo far
as humane reaſon is permitted to penetrate, confining my ſelf
within the bounds of conjectures, and probable reaſons, I will
ſay a little more reſolutely than Simplicius doth, that amongſt
all the ingenuous ſubtilties I ever heard, I have never met with
any thing of greater admiration to my intellect, nor that hath
more abſolutely captivated my judgment, (alwayes excepting
pure Geometrical and Arithmetical Demonſtrations) than theſe
two conjectures taken, the one from the ſtations and
tions of the five Planets, and the other from theſe irregularities of
the motions of the Solar ſpots: and becauſe they ſeem to me ſo
eaſily and clearly to aſſign the true reaſon of ſo extravagant
pearances, ſhewing as if they were but one ſole ſimple motion,
mixed with ſo many others, ſimple likewiſe, but different from
each other, without introducing any difficulty, rather with
ating thoſe that accompany the other Hypotheſis; I am
ing that I may rationally conclude, that thoſe who
ouſly withſtand this Doctrine, either never heard, or never
derſtood, theſe ſo convincing arguments.
SALV. I will not aſcribe unto them the title either of
vincing, or non-convincing; in regard my intention is not, as I
have ſeveral times told you, to reſolve any thing upon ſo high a
queſtion, but onely to propoſe thoſe natural and Aſtronomicall
reaſons, which, for the one and other Syſteme, may be produced
by me, leaving the determination to others; which
on cannot at laſt, but be very manifeſt: for one of the two
tions being of neceſſity to be true, and the other of neceſſity to
be falſe, it is a thing impoſſible that (alwayes confining our ſelves
1within the limits of humane doctrine) the reaſons alledged for
the true Hypotheſis ſhould not manifeſt themſelves as concludent
as thoſe for the contrary vain and ineffectual.
SAGR. It will be time therefore, that we hear the objections
of the little Book of^{*} Concluſions, or Diſquiſitions which Simpli-

cius did bring with him.
* I ſhould have
told you, that the
true name of this
concealed
thour is
pher Scheinerus,
and its title
quiſitiones
thematicæ.
SIMP. Here is the Book, and this is the place where the
thor firſt briefly deſcribeth the Syſteme of the world, according
to the Hypotheſis of Copernicus, ſaying, Terram igitur unà cum
Luna, totoque hoc elementari mundo Copernicus, &c.
SALV. Forbear a little, Simplicius, for methinks that this
Authour, in this firſt entrance, ſhews himſelf to be but very ill
verſt in the Hypotheſis which he goeth about to confute, in
gard, he ſaith that Copernicus maketh the Earth, together with
the Moon, to deſcribe the ^{*} grand Orb in a year moving from
Eaſt to Weſt; a thing that as it is falſe and impoſſible, ſo was it

never affirmed by Copernicus, who rather maketh it to move the
contrary way, I mean from Weſt to Eaſt, that is, according to
the order of the Signes; whereupon we come to think the ſame
to be the annual motion of the Sun, conſtituted immoveable in
the centre of the Zodiack. See the too adventurous confidence
of this man; to undertake the confutation of anothers Doctrine,
and yet to be ignorant of the primary fundamentals; upon which
his adverſary layeth the greateſt and moſt important part of all
the Fabrick. This is a bad beginning to gain himſelf credit
with his Reader; but let us go on.
* I.e. the Ecliptick
SIMP. Having explained the Univerſal Syſteme, he beginneth
to propound his objections againſt this annual motion: and
the firſt are theſe, which he citeth Ironically, and in deriſion of

Copernicus, and of his followers, writing that in this phantaſtical
Hypotheſis of the World one muſt neceſſarily maintain very
groſſe abſurdities; namely, that the Sun, Venus, and Mercury
are below the Earth; and that grave matters go naturally
wards, and the light downwards; and that Chriſt, our Lord and
Redeemer, aſcended into Hell, and deſcended into Heaven, when
he approached towards the Sun, and that when Joſhuah
manded the Sun to ſtand ſtill, the Earth ſtood ſtill, or the Sun
moved a contrary way to that of the Earth; and that when the
Sun is in Cancer, the Earth runneth through Capricorn; and that
the Hyemal (or Winter) Signes make the Summer, and the
Æſtival Winter; and that the Stars do not riſe and ſet to
the Earth, but the Earth to the Stars; and that the Eaſt
neth in the Weſt, and the Weſt in the Eaſt; and, in a word,
that almoſt the whole courſe of the World is inverted.
Inſtances of a
certain Book
nically propounded
againſt
cus.
SALV. Every thing pleaſeth me, except it be his having
1mixed places out of the ſacred Scriptures (alwayes venerable, and
to be rever'd) amongſt theſe, but two ſcurrilous fooleries, and
attempting to wound with holy Weapons, thoſe who
phating in jeſt, and for divertiſement, neither affirm nor deny,
but, ſome preſuppoſals and poſitions being aſſumed, do
arly argue.
SIMP. Truth is, he hath diſpleaſed me alſo, and that not a
little; and eſpecially, by adding preſently after that, howbeit,
the Copernichists anſwer, though but very impertinently to theſe
and ſuch like other reaſons, yet can they not reconcile nor anſwer
thoſe things that follow.
SALV. This is worſe than all the reſt; for he pretendeth to
have things more efficacious and concludent than the Authorities
of the ſacred Leaves; But I pray you, let us reverence them,
and paſſe on to natural and humane reaſons: and yet if he give
us amongſt his natural arguments, things of no more ſolidity,
than thoſe hitherto alleadged, we may wholly decline this
taking, for I as to my own parricular, do not think it fit to ſpend
words in anſwering ſuch trifling impertinencies. And as to what
he ſaith, that the Copernicans anſwer to theſe objections, it is
moſt falſe, nor may it be thought, that any man ſhould ſet him
ſelf to waſt his time ſo
Suppoſing the
annual motion to
belong to the Earth,
it followeth, that
one fixed Star, is
bigger than the
whole grand Orb.
SIMP. I concur with you in the ſame judgment; therefore
let us hear the other inſtances that he brings, as much ſtronger.
And obſerve here, how he with very exact computations
eth, that if the grand Orb of the Earth, or the ecliptick, in which
Copernicus maketh it to run in a year round the Sun, ſhould be
as it were, inſenſible, in reſpect of the immenſitie of the Starry
Sphære, according as the ſaid Copernicus, ſaith it is to be
poſed, it would be neceſſary to grant and confirm, that the fixed
Stars were remote from us, an unconceivable diſtance, and that
the leſſer of them, were bigger than the whole grand Orb
ſaid, and ſome other much bigger than the whole Sphære of
turn; Maſſes certainly too exceſſively vaſt, unimaginable, and
incredible.
Tycho his
gument grounded
upon a falſe
theſis.
SALV. I have heretofore ſeen ſuch another objection brought
by Tycho againſt Copernicus, and this is not the firſt time that I
have diſcovered the fallacy, or, to ſay better, the fallacies of this
Argumemtation, founded upon a moſt falſe Hypotheſis, and upon

a Piopoſition of the ſaid Copernicus, underſtood by his
ries, with too punctual a nicity, according to the practiſe of thoſe
pleaders, who finding the flaw to be in the very merit of their
cauſe, keep to ſome one word, fallen unawares from the
ry partie, and fly out into loud and tedious deſcants upon that.
But for your better information; Copernicus having declared
1thoſe admirable conſequences which are derived from the Earths

annual motion, to the other Planets, that is to ſay, of the ^{*}

ons and retrogradations of the three uppermoſt in particular; he
ſubjoyneth, that this apparent mutation (which is diſcerned more
in Mars than in Jupiter, by reaſon Jupiter is more remote, and
yet leſſe in Saturn, by reaſon it is more remote than Jupiter) in
the fixed Stars, did remain imperceptible, by reaſon of their
immenſe remoteneſſe from us, in compariſon of the diſtances of
Jupiter or Saturn. Here the Adverſaries of this opinion riſe up,
and ſuppoſing that fore-named imperceptibility of Copernicus, as
if it had been taken by him, for a real and abſolute thing of
thing, and adding, that a fixed Star of one of the leſſer
tudes, is notwithſtanding perceptible, ſeeing that it cometh
der the ſence of ſeeing, they go on to calculate with the
vention of other falſe aſſumptions, and concluding that it is
ſary by the Copernican Doctrine, to admit, that a fixed Star is much
bigger than the whole grand Orb. Now to diſcover the vanity

of this their whole proceeding, I ſhall ſhew that a fixed Star of the
ſixth magnitude, being ſuppoſed to be no bigger than the Sun,
one may thence conclude with true demonſtrations, that the
ſtance of the ſaid fixed Stars from us, cometh to be ſo great, that
the annual motion of the Earth, which cauſeth ſo great and
notable variations in the Planets, appears ſcarce obſervable in
them; and at the ſame time, I will diſtinctly ſhew the groſs
fallacies, in the aſſumptions of Copernicus his Adverſaries.
Litigious Lawyers
that are
ed in an ill cauſe,
keep cloſe to ſome
expreſſion fallen
from the adverſe
party at unawares.
* Or progreſſions.
The apparent
diverſity of motion
in the Planets, is
inſenſible in the
fixed Start.
Suppoſing that a
fixed Star of the
ſixth magnitude is
no bigger than the
Sun, the diverſitie
which is ſo great
in the Planets, in
the fixed Stars is
almost inſenſible.
And firſt of all, I ſuppoſe with the ſaid Copernicus, and alſo

with his oppoſers, that the Semidiameter of the grand Orb, which
is the diſtance of the Earth from the Sun, containeth 1208
diameters of the ſaid Earth. Secondly, I premiſe with the
ance aforeſaid, and of truth, that the ^{*} apparent diameter of the

Sun in its mean diſtance, to be about half a degree, that is, 30.
min. prim. which are 1800. ſeconds, that is, 108000. thirds.
And becauſe the apparent Diameter of a fixed Star of the firſt

magnitude, is no more than 5. ſeconds, that is, 300. thirds, and
the Diameter of a fixed Star of the ſixth magnitude, 50. thirds,
(and herein is the greateſt errour of the Anti-Copernicans)

fore the Diameter of the Sun, containeth the Diameter of a
fixed Star of the ſixth magnitude 2160 times. And therefore
if a fixed Star of the ſixth magnitude, were ſuppoſed to be really
equal to the Sun, and not bigger, which is the ſame as to ſay, if
the Sun were ſo far removed, that its Diameter ſhould ſeem to
be one of the 2160. parts of what it now appeareth, its diſtance
ought of neceſſity to be 2160. times greater than now in effect it
is, which is as much as to ſay, that the diſtance of the fixed Stars
of the ſixth magnitude, is 2160. Semidiameters of the grand
1Orb. And becauſe the diſtance of the Sun from the Earth,

tains by common conſent 1208. Semidiameters of the ſaid Earth,
and the diſtance of the fixed Stars (as hath been ſaid) 2160.
Semediameters of the grand Orb, therefore the Semediameter of
the Earth is much greater (that is almoſt double) in compariſon
of the grand Orb, than the Semediameter of the grand Orb, in

relation to the diſtance of the Starry Sphære; and therefore the
variation of aſpect in the fixed Stars, cauſed by the Diameter of
the grand Orb, can be but little more obſervable, than that which
is obſerved in the Sun, occaſioned by the Semediameter of the
Earth.
The diſtance of
the Sun, containeth
1208 Semid. of the
Earth.
* The Diameter
of the Sun, half a
degree.
The Diameter
of a fixed Star, of
the firſt
tude, and of one of
the ſixth.
The apparent
Diameter of the
Sun, how much it
is bigger than that
of a fixed ſtar.
The diſtance of
a fixed ſtar of the
ſixth magnitude,
how much it is, the
ſtar being ſuppoſed
to be equal to the
Sun.
In the fixed ſtars
the diverſitie of
ſpect, cauſed by
the grand Orb, is
little more then
that cauſed by the
Earth in the Snn.
SAGR. This is a great fall for the firſt ſtep.
SALV. It is doubtleſſe an errour; for a fixed Star of the ſixth

magnitude, which by the computation of this Authour, ought,
for the upholding the propoſition of Copernicus, to be as big as
the whole grand Orb, onely by ſuppoſing it equal to the Sun,
which Sun is leſſe by far, than the hundred and ſix milionth part
of the ſaid grand Orb, maketh the ſtarry Sphære ſo great and high
as ſufficeth to overthrow the inſtance brought againſt the ſaid
pernicus.
A ſtar of the
ſixth magnitude,
ſuppoſed by Tycho
and the Authour
of the Book of
cluſions, an
dred and ſix
ons of times bigger
than needs.
SAGR. Favour me with this computation.
SALV. The ſupputation is eaſie and ſhort. The Diameter of
the Sun, is eleven ſemediameters of the Earth, and the Diameter

of the grand Orb, contains 2416. of thoſe ſame ſemediameters,
by the aſcent of both parties; ſo that the Diameter of the ſaid
Orb, contains the Suns Diameter 220. times very near. And
becauſe the Spheres are to one another, as the Cubes of their
ameters, let us make the Cube of 220. which is 106480000. and
we ſhall have the grand Orb, an hundred and ſix millions, four
hundred and eighty thouſand times bigger than the Sun, to which
grand Orb, a ſtar of the fixth magnitude, ought to be equal,
cording to the aſſertion of this Authour.
The
on of the
tude of the fixed
Stars, in reſpect to
the grand Orb.
SAGR. The errour then of theſe men, conſiſteth in being
treamly miſtaken, in taking the apparent Diameter of the fixed
Stars.
SALV. This is one, but not the onely errour of them; and

indeed, I do very much admire how ſo many Aſtronomers, and
thoſe very famous, as are Alfagranus, Albategnus, Tebizius, and
much more modernly the Tycho's and Clavius's, and in ſumm,
all the predeceſſors of our Academian, ſhould have been ſo groſly
miſtaken, in determining the magnitudes of all the Stars, as well
ſixed as moveable, the two Luminaries excepted out of that
ber; and that they have not taken any heed to the adventitious
irradiations that deceitfully repreſent them an hundred and more
times bigger, than when they are beheld, without thoſe
1ous rayes, nor can this their inadvertency be excuſed, in regard
that it was in their power to have beheld them at their pleaſure
without thoſe treſſes, which is done, by looking upon them at
their firſt appearance in the evening, or their laſt occultation in

the comming on of day; and if none of the reſt, yet Venus,
which oft times is ſeen at noon day, ſo ſmall, that one muſt
pen the ſight in diſcerning it; and again, in the following night,
ſeemeth a great flake of light, might advertiſe them of their
lacy; for I will not believe that they thought the true Diſcus to
be that which is ſeen in the obſcureſt darkneſſes, and not that
which is diſcerned in the luminous Medium: for our lights, which
ſeen by night afar off appear great, and neer at hand ſhew their
true luſtre to be terminate and ſmall, might have eaſily have
made them cautious; nay, if I may freely ſpeak my thoughts, I
abſolutely believe that none of them, no not Tycho himſelf, ſo
accurate in handling Aſtronomical Inſtruments, and that ſo great
and accurate, without ſparing very great coſt in their
ction, did ever go about to take and meaſure the apparent
meter of any Star, the Sun and Moon excepted; but I think,
that arbitrarily, and as we ſay, with the eye, ſome one of the
more antient of them pronounced the thing to be ſo and ſo, and
that all that followed him afterwards, without more ado, kept
cloſe to what the firſt had ſaid; for if any one of them had
plied himſelf to have made ſome new proof of the ſame, he would
doubtleſſe have diſcovered the fraud.
A common
rour of all the
ſtronomers,
ing the magnitude
of the ſtars.
Venus renders the
errour of
mers in
ing the magnitudes
of ſtars
ble.
SAGR. But if they wanted the Teleſcope, and you have
ready ſaid, that our Friend with that ſame Inſtrument came to
the knowledge of the truth, they ought to be excuſed, and not
accuſed of ignorance.
SALV. This would hold good, if without the Teleſcope the
buſineſſe could not be effected. Its true, that this Inſtrument by
ſhewing the Diſcus of the Star naked, and magnified an
dred or a thouſand times, rendereth the operation much more
ſie, but the ſame thing may be done, although not altogether ſo
exactly, without the Inſtrument, and I have many times done
the ſame, and my method therein was this. I have cauſed a rope

to be hanged towards ſome Star, and I have made uſe of the
Conſtellation, called the Harp, which riſeth between the North
and ^{*} North-eaſt, and then by going towards, and from

the ſaid rope, interpoſed between me and the Star, I have found
the place from whence the thickneſſe of the rope hath juſt hid
the Star from me: this done, I have taken the diſtance from the
eye to the rope, which was one of the ſides including the angle
that was compoſed in the eye, and ^{*} which inſiſteth upon the

thickneſſe of the rope, and which is like, yea the ſame with the
1angle in the Starry Sphere, that inſiſteth upon the diameter of
the Star, and by the proportion of the ropes thickneſſe to the
diſtance from the eye to the rope, by the table of Arches and
Chords, I have immediately found the quantity of the angle;
ſing all the while the wonted caution that is obſerved in taking
angles ſo acute, not to forme the concourſe of the viſive rayes
in the centre of the eye, where they are onely refracted, but
beyond the eye, where really the pupils greatneſſe maketh them
to concur.
A way to
ſure the apparent
diameter of a ſtar.
* Rendred in
Latine Corum, that
is to ſay,
weſt.
* i.e. Is
ded by.
SAGR. I apprehend this your cautelous procedure, albeit I
have a kind of hæſitancy touching the ſame, but that which moſt
puzzleth me is, that in this operation, if it be made in the dark
of night, methinks that you meaſure the diameter of the
ted Diſcus, and not the true and naked face of the Star.
SALV. Not ſo, Sir, for the rope in covering the naked body
of the Star, taketh away the rayes, which belong not to it, but
to our eye, of which it is deprived ſo ſoon as the true Diſcus
thereof is hid; and in making the obſervation, you ſhall ſee, how
unexpectedly a little cord will cover that reaſonable big body of
light, which ſeemed impoſſible to be hid, unleſſe it were with a
much broader Screene: to meaſure, in the next place, and
ctly to find out, how many of thoſe thickneſſes of the rope
poſe in the diſtance between the ſaid rope and the eye, I take not
onely one diameter of the rope, but laying many pieces of the
ſame together upon a Table, ſo that they touch, I take with a
pair of Compaſſes the whole ſpace occupied by fifteen, or
ty of them, and with that meaſure I commenſurate the diſtance
before with another ſmaller cord taken from the rope to the
courſe of the viſive rayes. And with this ſufficiently-exact
ration I finde the apparent diameter of a fixed Star of the firſt
magnitude, commonly eſteemed to be 2 min. pri. and alſo 3 min.
prim. by Tycho in his Aſtronomical Letters, cap. 167. to be no

more than 5 ſeconds, which is one of the 24. or 36. parts of what
they have held it: ſee now upon what groſſe errours their
ctrines are founded.
The diameter of
a fixed ſtar of the
firſt magnitude not
more than five ſec.
min.
SAGR. I ſee and comprehend this very well, but before we
paſſe any further, I would propound the doubt that ariſeth in
me in the finding the concourſe [or interſection] of the viſual
rayes beyond the eye, when obſervation is made of objects
prehended between very acute angles; and my ſcruple proceeds
from thinking, that the ſaid concourſe may be ſometimes more
remote, and ſometimes leſſe; and this not ſo much, by meanes
of the greater or leſſer magnitude of the object that is beheld, as
becauſe that in obſerving objects of the ſame bigneſſe, it ſeems
to me that the concourſe of the rayes, for certain other
1ſpects ought to be made more and leſſe remote from the eye.
SALV. I ſee already, whither the apprehenſion of Sagredus,
a moſt diligent obſerver of Natures ſecrets, tendeth; and I

would lay any wager, that amongſt the thouſands that have
ſerved Cats to contract and inlarge the pupils of their eyes very
much, there are not two, nor haply one that hath obſerved the
like effect to be wrought by the pupils of men in ſeeing, whilſt
the medium is much or little illumin'd, and that in the open light
the circlet of the pupil diminiſheth conſiderably: ſo that in
king upon the face or Diſcus of the Sun, it is reduced to a
neſſe leſſer than a grain of ^{*} Panick, and in beholding objects

that do not ſhine, and are in a leſſe luminous medium, it is
god to the bigneſſe of a Lintel or more; and in ſumme this
expanſion and contraction differeth in more than decuple
portion: From whence it is manifeſt, that when the pupil is
much dilated, it is neceſſary that the angle of the rayes
courſe be more remote from the eye; which happeneth in
holding objects little luminated. This is a Doctrine which
gredus hath, juſt now, given me the hint of, whereby, if we
were to make a very exact obſervation, and of great
quence, we are advertized to make the obſervation of that
courſe in the act of the ſame, or juſt ſuch another operation; but
in this our caſe, wherein we are to ſhew the errour of
mers, this accurateneſſe is not neceſſary: for though we ſhould,
in favour of the contrary party, ſuppoſe the ſaid concourſe to be
made upon the pupil it ſelf, it would import little, their miſtake
being ſo great. I am not certain, Sagredus, that this would have
been your objection.
The circle of the
pupil of the eye
largeth and
tracteth.
+ Panicum, a
ſmall grain like to
Mill, I take it to be
the ſame with that
called Bird Seed.
SAGR. It is the very ſame, and I am glad that it was not
together without reaſon, as your concurrence in the ſame
reth me; but yet upon this occaſion I would willingly hear what
way may be taken to finde out the diſtance of the concourſe of
the viſual rayes.
SALV. The method is very eaſie, and this it is, I take two
long^{*} labels of paper, one black, and the other white, and make

the black half as broad as the white; then I ſtick up the white
gainſt a wall, and far from that I place the other upon a ſtick, or
other ſupport, at a diſtance of fifteen or twenty yards, and
ding from this, ſecond another ſuch a ſpace in the ſame right line,
it is very manifeſt, that at the ſaid diſtance the right lines will
concur, that departing from the termes of the breadth of the
white piece, ſhall paſſe cloſe by the edges of the other label
ced in the mid-way; whence it followeth, that in caſe the eye
were placed in the point of the ſaid concourſe or interſection,
the black ſlip of paper in the midſt would preciſely hide the
1poſite blank, if the ſight were made in one onely point; but if we
ſhould find, that the edges of the white cartel appear diſcovered,
it ſhall be a neceſſary argument that the viſual rayes do not iſſue
from one ſole point. And to make the white label to be hid by
the black, it will be requiſite to draw neerer with the eye:
Therefore, having approached ſo neer, that the intermediate
bel covereth the other, and noted how much the required
proximation was, the quantity of that approach ſhall be the
tain meaſure, how much the true concourſe of the viſive rayes, is
remote from the eye in the ſaid operation, and we ſhall moreover
have the diameter of the pupil, or of that circlet from whence
the viſive rayes proceed: for it ſhall be to the breadth of the
black paper, as is the diſtance from the concourſe of the lines,
that are produced by the edges of the papers to the place where
the eye ſtandeth, when it firſt ſeeth the remote paper to be hid
by the intermediate one, as that diſtance is, I ſay, to the diſtance
that is between thoſe two papers. And therefore when we
would, with exactneſſe, meaſure the apparent diameter of a Star,
having made the obſervation in manner, as aforeſaid, it would be
neceſſary to compare the diameter of the rope to the diameter of
the pupil; and having found v.g. the diameter of the rope to be
quadruple to that of the pupil, and the diſtance of the eye from
the rope to be, for example, thirty yards, we would ſay, that the
true concourſe of the lines produced from the ends or
ties of the diameter of the ſtar, by the extremities of the
meter of the rope, doth fall out to be fourty yards remote from
the ſaid rope, for ſo we ſhall have obſerved, as we ought, the
portion between the diſtance of the rope from the concourſe of
the ſaid lines, and the diſtance from the ſaid concourſe to the
place of the eye, which ought to be the ſame that is between
the diameter of the rope, and diameter of the pupil.
* Striſce.
How to find the
diſtance of the rays
concourſe from the
pupil.
SAGR. I have perfectly underſtood the whole buſineſſe, and
therefore let us hear what Simplicius hath to alledge in defence of
the Anti-Copernicans.
SIMP. Albeit that grand and altogether incredible
nience inſiſted upon by theſe adverſaries of Copernicus be much
moderated and abated by the diſcourſe of Salviatus, yet do I
not think it weakened ſo, as that it hath not ſtrength enough left
to foil this ſame opinion. For, if I have rightly apprehended the
chief and ultimate concluſion, in caſe, the ſtars of the ſixth
nitude were ſuppoſed to be as big as the Sun, (which yet I can
hardly think) yet it would ſtill be true, that the grand Orb [or
Ecliptick] would occaſion a mutation and variation in the ſtarry
Sphere, like to that which the ſemidiameter of the Earth
ceth in the Sun, which yet is obſervable; ſo that neither that, no
1nor a leſſe mutation being diſcerned in the fixed Stars, methinks
that by this means the annual motion of the Earth is deſtroyed
and overthrown.
SALV. You might very well ſo conclude, Simplicius, if we
had nothing elſe to ſay in behalf of Copernicus: but we have
many things to alledge that yet have not been mentioned; and
as to that your reply, nothing hindereth, but that we may
poſe the diſtance of the fixed Stars to be yet much greater than
that which hath been allowed them, and you your ſelf, and
ever elſe will not derogate from the propoſitions admitted by
Piolomy's ſectators, muſt needs grant it as a thing moſt requiſite
to ſuppoſe the Starry Sphere to be very much bigger yet than
that which even now we ſaid that it ought to be eſteemed. For

all Aſtronomers agreeing in this, that the cauſe of the greater
tardity of the Revolutions of the Planets is, the majority of
their Spheres, and that therefore Saturn is more flow than
piter, and Jupiter than the Sun, for that the firſt is to deſcribe a
greater circle than the ſecond, and that than this later, &c.
ſidering that Saturn v.g. the altitude of whoſe Orb is nine times
higher than that of the Sun, and that for that cauſe the time of
one Revolution of Saturn, is thirty times longer than that of a
converſion of the Sun, in regard that according to the Doctrine
of Ptolomy, one converſion of the ſtarry Sphere is finiſhed in
36000. years, whereas that of Saturn is conſummate in thirty,
and that of the Sun in one, arguing with a like proportion, and

ſaying, if the Orb of Saturn, by reaſon it is nine times bigger
than that of the Sun, revolves in a time thirty times longer, by
converſion, how great ought that Orb to be, which revolves
36000. times more ſlowly? it ſhall be found that the diſtance of
the ſtarry Sphere ought to be 10800 ſemidiameters of the grand
Orb, which ſhould be full five times bigger than that, which even
now we computed it to be, in caſe that a fixed Star of the ſixth
magnitude were equal to the Sun. Now ſee how much leſſer yet,
upon this account, the variation occaſioned in the ſaid Stars, by
the annual motion of the Earth, ought to appear. And if at the
ſame rate we would argue the diſtance of the ſtarry Sphere from

Jupiter, and from Mars, that would give it us to be 15000. and
this 27000 ſemidiameters of the grand Orb, to wit, the firſt
ſeven, and the ſecond twelve times bigger than what the
nitude of the fixed Star, ſuppoſed equal to the Sun, did make
it.
All
mers agree that
the greater
tudes of the Orbes
is the cauſe of the
tardity of the
verſions.
By another
poſition taken from
Aſtronomers, the
diſtance of the
ed Stars is
lated to be 10800
ſemidiameters of
the grand Orb.
By the proportion
of Jupiter and of
Mais, the ſtarry
Sphere is found to
be yet more remote.
SIMP. Methinks that to this might be anſwered, that the
tion of the ſtarry Sphere hath, ſince Ptolomy, been obſerved not
to be ſo ſlow as he accounted it; yea, if I miſtake. not, I have
heard that Copernicus himſelf made the Obſervation.
1
SALV. You ſay very well; but you alledge nothing in that
which may favour the cauſe of the Ptolomœans in the leaſt, who
did never yet reject the motion of 36000. years in the ſtarry
Sphere, for that the ſaid tardity would make it too vaſt and
menſe. For if that the ſaid immenſity was not to be ſuppoſed in
Nature, they ought before now to to have denied a converſion
ſo ſlow as that it could not with good proportion adapt it ſelf,
ſave onely to a Sphere of monſtrous magnitude.
SAGR. Pray you, Salviatus, let us loſe no more time in
ceeding, by the way of theſe proportions with people that are apt
to admit things moſt diſ-proportionate; ſo that its impoſſible
to win any thing upon them this way: and what more
tionate proportion can be imagined than that which theſe men
ſwallow down, and admit, in that writing, that there cannot be a
more convenient way to diſpoſe the Cœleſtial Spheres, in order,
than to regulate them by the differences of the times of their
riods, placing from one degree to another the more flow above
the more ſwift, when they have conſtituted the Starry Sphere
higher than the reſt, as being the ſloweſt, they frame another
higher ſtill than that, and conſequently greater, and make it
volve in twenty four hours, whilſt the next below, it moves not
round under 36000. years?
SALV. I could wiſh, Simplicius, that ſuſpending for a time
the affection rhat you bear to the followers of your opinion, you
would ſincerely tell me, whether you think that they do in their
minds comprehend that magnitude, which they reject afterwards
as uncapable for its immenſity to be aſcribed to the Univerſe.
For I, as to my own part, think that they do not; But believe,

that like as in the apprehenſion of numbers, when once a man
begins to paſſe thoſe millions of millions, the imagination is
founded, and can no longer form a conceipt of the ſame, ſo it
happens alſo in comprehending immenſe magnitudes and
ces; ſo that there intervenes to the comprehenſion an effect like
to that which befalleth the ſenſe; For whileſt that in a ſerene
night I look towards the Stars, I judge, according to ſenſe, that
their diſtance is but a few miles, and that the fixed Stars are not a
jot more remote than Jupiter or Saturn, nay than the Moon.
But without more ado, conſider the controverſies that have paſt
between the Aſtronomers and Peripatetick Philoſophers, upon
occaſion of the new Stars of Caſſiopeia and of Sagittary, the
ſtronomers placing them amongſt the fixed Stars, and the
ſophers believing them to be below the Moon. So unable is our
ſenſe to diſtinguiſh great diſtances from the greateſt, though theſe
be in reality many thouſand times greater than thoſe. In a word,
I ask of thee, O fooliſh man! Doth thy imagination comprehend
1that vaſt magnitude of the Univerſe, which thou afterwards
eſt to be too immenſe? If thou comprehendeſt it; wilt thou
hold that thy apprehenſion extendeth it ſelf farther than the
vine Power? wilt thou ſay, that thou canſt imagine greater
things than thoſe which God can bring to paſſe? But if thou
apprehendeſt it not, why wilt thou paſſe thy verdict upon things
beyond thy comprehenſion?
Immenſe
nitudes and
bers are
henſible by our
derſtanding.
SIMP. All this is very well, nor can it be denied, but that
Heaven may in greatneſſe ſurpaſſe our imagination, as alſo that
God might have created it thouſands of times vaſter than now it
is; but we ought not to grant any thing to have been made in
vain, and to be idle in the Univerſe. Now, in that we ſee this
mirable order of the Planets, diſpoſed about the Earth in
ces proportionate for producing their effects for our advantage,
to what purpoſe is it to interpoſe afterwards between the ſublime
Orb of Saturn and the ſtarry Sphere, a vaſt vacancy, without any
ſtar that is ſuperfluous, and to no purpoſe? To what end? For
whoſe profit and advantage?
SALV. Methinks we arrogate too much to our ſelves,
cius, whilſt we will have it, that the onely care of us, is the
æquate work, and bound, beyond which the Divine Wiſdome
and Power doth, or diſpoſeth of nothing. But I will not
ſent, that we ſhould ſo much ſhorten its hand, but deſire that we
may content our ſelves with an aſſurance that God and Nature

are ſo imployed in the governing of humane affairs, that they
could not more apply themſelves thereto, although they had no
other care than onely that of mankind; and this, I think, I am
able to make out by a moſt pertinent and moſt noble example,
taken from the operation of the Suns light, which whileſt it

tracteth theſe vapours, or ſcorcheth that plant, it attracteth, it
ſcorcheth them, as if it had no more to do; yea, in ripening that
bunch of grapes, nay that one ſingle grape, it doth apply it ſelf
ſo, that it could not be more intenſe if the ſum of all its buſineſs
had been the only maturation of that grape. Now if this grape
receiveth all that it is poſſible for it to receive from the Sun, not
ſuffering the leaſt injury by the Suns production of a thouſand
other effects at the ſame time; it would be either envy or folly
to blame that grape, if it ſhould think or wiſh that the Sun would
onely appropriate its rayes to its advantage. I am confident that
nothing is omitted by the Divine Providence, of what concernes
the government of humane affairs; but that there may not be
other things in the Univerſe, that depend upon the ſame infinite
Wiſdome, I cannot, of my ſelf, by what my reaſon holds forth
to me, bring my ſelf to believe. However, if it were not ſo,
yet ſhould I not forbear to believe the reaſons laid before me by
1ſome more ſublime intelligence. In the mean time, if one
ſhould tell me, that an immenſe ſpace interpoſed between the
Orbs of the Planets and the Starry Sphere, deprived of ſtars and
idle, would be vain and uſeleſſe, as likewiſe that ſo great an
immenſity for receipt of the fixed ſtars, as exceeds our utmoſt
comprehenſion would be ſuperfluous, I would reply, that it is
raſhneſſe to go about to make our ſhallow reaſon judg of the
Works of God, and to call vain and ſuperfluous, whatſoever
thing in the Univerſe is not ſubſervient to us.
God & Nature
do imploy
ſelves in caring
for men, as if they
minded nothing
elſe.
An example of
Gods care of
kind taken from
the Sun.
SAGR. Say rather, and I believe you would ſay better, that

we know not what is ſubſervient to us; and I hold it one of the
greateſt vanities, yea follies, that can be in the World, to ſay,
becauſe I know not of what uſe Jupiter or Saturn are to me, that
therefore theſe Planets are ſuperfluous, yea more, that there are
no ſuch things in rerum natura; when as, oh fooliſh man! I
know not ſo much as to what purpoſe the arteries, the griſtles,
the ſpleen, the gall do ſerve; nay I ſhould not know that I have
a gall, ſpleen, or kidneys, if in many deſected Corps, they were
not ſhewn unto me; and then onely ſhall I be able to know what
the ſpleen worketh in me, when it comes to be taken from me.
To be able to know what this or that Cœleſtial body worketh in

me (ſeeing you will have it that all their influences direct
ſelves to us) it would be requiſite to remove that body for ſome
time; and then whatſoever effect I ſhould find wanting in me, I
would ſay that it depended on that ſtar. Moreover, who will
ſume to ſay that the ſpace which they call too vaſt and uſeleſſe
between Saturn and the fixed ſtars, is void of other mundane
dies? Muſt it be ſo, becauſe we do not ſee them? Then the four

Medicean Planets, and the companions of Saturn came firſt
to Heaven, when we began to ſee them, and not before? And
by this rule the innumerable other fixed ſtars had no exiſtence
before that men did look on them? and the cloudy
ons called Nebuloſœ were at firſt only white flakes, but afterwards
with the Teleſcope we made them to become conſtellations of
many lucid and bright ſtars. Oh preſumptious, rather oh raſh
ignorance of man!
It is great
neſſe to cenſure
that to be
ous in the Univerſe,
which we do not
perceive to be made
for us.
By depriving
Heaven of ſome
ſtar, one might
come to know what
influence it hath
upon us.
Many things
may be in Heauen,
that are inviſible
to us
SALV. It's to no purpoſe Sagredus, to ſally out any more into
theſe unprofitable exaggerations: Let us purſue our intended
deſigne of examining the validity of the reaſons alledged on
ther ſide, without determining any thing, remitting the
ment thereof when we have done, to ſuch as are more knowing.
Returning therefore to our natural and humane diſquiſitions, I

ſay, that great, little, immenſe, ſmall, &c. are not abſolute,
but relative terms, ſo that the ſelf ſame thing compared with
divers others, may one while be called immenſe, and another
1while imperceptible, not to ſay ſmall. This being ſo, I demand
in relation to what the Starry Sphere of Copernicus may be
led over vaſt. In my judgment it cannot be compared, or ſaid
to be ſuch, unleſſe it be in relation to ſome other thing of the
ſame kind; now let us take the very leaſt of the ſame kind,

which ſhall be the Lunar Orb; and if the Starry Orb may be ſo
cenſured to be too big in reſpect to that of the Moon, every
ther magnitude that with like or greater proportion exceedeth
another of the ſame kind, ought to be adjudged too vaſt, and
for the ſame reaſon to be denied that they are to be found in the
World; and thus an Elephant, and a Whale, ſhall without more
ado be condemned for Chymæra's, and Poetical fictions,
cauſe that the one as being too vaſt in relation to an Ant, which
is a Terreſtrial animal, and the other in reſpect to the ^{*}Gudgeon,

which is a Fiſh, and are certainly ſeen to be in rerum natura,
would be too immeaſurable; for without all diſpute, the
phant and Whale exceed the Ant and Gudgeon in a much
er proportion than the Starry Sphere doth that of the Moon,
although we ſhould fancy the ſaid Sphere to be as big as the
pernican Syſteme maketh it. Moreover, how hugely big is the

Sphere of Jupiter, or that of Saturn, defigned for a receptacle
but for one ſingle ſtar; and that very ſmall in compariſon of one
of the fixed? Certainly if we ſhould aſſign to every one of the
fixed ſtars for its receptacle ſo great a part of the Worlds ſpace,
it would be neceſſary to make the Orb wherein ſuch innumerable
multitudes of them reſide, very many thouſands of times
ger than that which ſerveth the purpoſe of Copernicus. Beſides,

do not you call a fixed ſtar very ſmall, I mean even one of the
moſt apparent, and not one of thoſe which ſhun our ſight; and
do we not call them ſo in reſpect of the vaſt ſpace circumfuſed?
Now if the whole Starry Sphere were one entire lucid body; who

is there, that doth not know that in an infinite ſpace there might be
aſſigned a diſtance ſo great, as that the ſaid lucid Sphere might
from thence ſhew as little, yea leſſe than a fixed ſtar, now
peareth beheld from the Earth? From thence therefore we
ſhould then judg that ſelf ſame thing to be little, which now from
hence we eſteem to be immeaſurably great.
Great, ſmall,
immenſe, &c. are
relative terms.
Vanity of thoſe
mens diſcour ſewho
judg the ſtarry
ſphere too vaſt in
the Copernican
Hypotheſis.
* Spilloncola, which
is here put for the
leaſt of Fiſhes.
The ſpace
ſigned to a fixed
ſtar, is much ieſſe
than that of a
net.
A ſtar is
led in reſpect of the
ſpace that environs
it.
The whole
ry ſphere beheld
from a great
ſtance might
pear as ſmall as
one ſingle ſtar.
SAGR. Great in my judgment, is the folly of thoſe who
would have had God to have made the World more proportinal
to the narrow capacities of their reaſon, than to his immenſe,
rather infinite power.
SIMP. All this that you ſay is very true; but that upon
which the adverſary makes a ſcruple, is, to grant that a fixed
ſtar ſhould be not onely equal to, but ſo much bigger than the
Sun; when as they both are particular bodies ſituate within the
1Starry Orb: “And indeed in my opinion this Authour very
pertinently queſtioneth and asketh: To what end, and
for whoſe ſake are ſuch huge machines made? Were they

produced for the Earth, for an inconſiderable point? And
why ſo remote? To the end they might ſeem ſo very ſmall,
and might have no influence at all upon the Earth? To

what purpoſe is ſuch a needleſſe monſtrous ^{*} immenſity
tween them and Saturn? All thoſe aſſertions fall to the
ground that are not upheld by probable reaſons.”
Inſtances of the
Authour of the
Concluſions by way
of interrogation.
Or Gulph.
SALV. I conceive by the queſtions which this perſon asketh,

that one may collect, that in caſe the Heavens, the Stars, and
the quantity of their diſtances and magnitudes which he hath
hitherto held, be let alone, (although he never certainly fancied
to himſelf any conceivable magnitude thereof) he perfectly
cerns and comprehends the benefits that flow from thence to the
Earth, which is no longer an inconſiderable thing; nor are they
any longer ſo remote as to appear ſo very ſmall, but big enough to
be able to operate on the Earth; and that the diſtance between
them and Saturn is very well proportioned, and that he, for all
theſe things, hath very probable reaſons; of which I would
ly have heard ſome one: but being that in theſe few words he

confounds and contradicts himſelf, it maketh me think that he
is very poor and ill furniſhed with thoſe probable reaſons, and
that thoſe which he calls reaſons, are rather fallacies, or dreams
of an over-weening fancy. For I ask of him, whether theſe

leſtial bodies truly operate on the Earth, and whether for the
working of thoſe effects they were produced of ſuch and ſuch
magnitudes, and diſpoſed at ſuch and ſuch diſtances, or elſe
whether they have nothing at all to do with Terrene mattets. If
they have nothing to do with the Earth; it is a great folly for us
that are Earth-born, to offer to make our ſelves arbitrators of
their magnitudes, and regulators of their local diſpoſitions,
ing that we are altogether ignorant of their whole buſineſſe and
concerns; but if he ſhall ſay that they do operate, and that they
are directed to this end, he doth affirm the ſame thing which a
little before he denied, and praiſeth that which even now he
condemned, in that he ſaid, that the Celeſtial bodies ſituate ſo
far remote as that they appear very ſmall, cannot have any
fluence at all upon the Earth. But, good Sir, in the Starry Sphere
pre-eſtabliſhed at its preſent diſtance, and which you did
knowledg to be in your judgment, well proportioned to have an
influence upon theſe Terrene bodies, many ſtars appear very
ſmall, and an hundred times as many more are wholly inviſible
unto us (which is an appearing yet leſſe than very ſmall)
therefore it is neceſſary that (contradicting your ſelf) you do
1now deny their operation upon the the Earth; or elſe that (ſtill
contradicting your ſelf) you grant that their appearing very ſmall
doth not in the leaſt leſſen their influence; or elſe that (and this
ſhall be a more ſincere and modeſt conceſſion) you acknowledg
and freely confeſſe, that our paſſing judgment upon their
nitudes and diſtances is a vanity, not to ſay preſumption or
raſhneſſe.
Anſwers to the
interrogatories of
the ſaid Authour.
The Auihour
of the
ons confound and
contradicts
ſelfin his
gations.
Inter ogatories
put to the
thour of the
cluſions, by which
the weakneſſe of
his is made appear.
SIMP. Truth is, I my ſelf did alſo, in reading this paſſage
perceive the manifeſt contradiction, in ſaying, that the Stars. (if
one may ſo ſpeak) of Copernicus appearing ſo very ſmall, could
not operate on the Earth, and not perceiving that he had granted
an influence upon the Earth to thoſe of Ptolomy, and his
tors, which appear not only very ſmall, but are, for the moſt
part, very inviſible.
SALV. But I proceed to another conſideration: What is the
reaſon, doth he ſay, why the ſtars appear ſo little? Is it haply,
becauſe they ſeem ſo to us? Doth not he know, that this

meth from the Inſtrument that we imploy in beholding them, to
wit, from our eye? And that this is true, by changing
ment, we ſhall ſee them bigger and bigger, as much as we will.
And who knows but that to the Earth, which beholdeth them
without eyes, they may not ſhew very great, and ſuch as in
ty they are? But it's time that, omitting theſe trifles, we come
to things of more moment; and therefore I having already
monſtrated theſe two things: Firſt, how far off the Firmament
ought to be placed to make, that the grand Orb cauſeth no
ter difference than that which the Terreſtrial Orb occaſioneth in
the remoteneſſe of the Sun; And next, how likewiſe to make
that a ſtar of the Firmament appear to us of the ſame bigneſſe,
as now we ſee it, it is not neceſſary to ſuppoſe it bigger than the
Sun; I would know whether Tycho, or any of his adherents hath
ever attempted to find out, by any means, whether any
rance be to be diſcovered in the ſtarry Sphere, upon which one
may the more reſolutely deny or admit the annual motion of
the Earth.
That remote
jects appeare ſo
ſmall, is the defect
of the eye, as
demonſtrated.
SAGR. I would anſwer for them, that there is not, no nor is

there any need there ſhould; ſeeing that it is Copernicus himſelf
that ſaith, that no ſuch diverſity is there: and they, arguing ad
hominem, admit him the ſame; and upon this aſſumption they
demonſtrate the improbability that followeth thereupon,
ly, that it would be neceſſary to make the Sphere ſo immenſe,
that a fixed ſtar, to appear unto us as great as it now ſeems, ought
of neceſſity to be of ſo immenſe a magnitude, as that it would
exceed the bigneſſe of the whole grand Orb, a thing, which
withſtanding, as they ſay, is altogether incredible.
1
Tycho nor his
followers ever
tempted to ſee
ther there are any
appearances in the
Firmament for or
against the annual
motion.
SALV. I am of the ſame judgment, and verily believe that
they argue contra hominem, ſtudying more to defend another
man, than deſiring to come to the knowledge of the truth. And

I do not only believe, that none of them ever applied themſelves
to make any ſuch obſervation, but I am alſo uncertain, whether
any of them do know what alteration the Earths annual motion
ought to produce in the fixed ſtars, in caſe the ſtarry Sphere were
not ſo far diſtant, as that in them the ſaid diverſity, by reaſon of
its minuity diſ-appeareth; for their ſurceaſing that inquiſition,
and referring themſelves to the meer aſſertion of Copernicus,
may very well ſerve to convict a man, but not to acquit him of
the fact: For its poſſible that ſuch a diverſity may be, and yet

not have been ſought for; or that either by reaſon of its
ty, or for want of exact Inſtruments it was not diſcovered by
pernicus; for though it were ſo, this would not be the firſt thing,
that he either for want of Inſtruments, or for ſome other defect
hath not known; and yet he proceeding upon other ſolid and
rational conjectures, affirmeth that, which the things by him not
diſcovered do ſeem to contradict: for, as hath been ſaid already,
without the Teleſcope, neither could Mars be diſcerned to
creaſe 60. times; nor Venus 40. more in that than in this
on; yea, their differences appear much leſſe than really they are:
and yet nevertheleſſe it is certainly diſcovered at length, that
thoſe mutations are the ſame, to an hair that the Copernican

ſteme required. Now it would be very well, if with the greateſt
accurateneſſe poſſible one ſhould enquire whether ſuch a
tion as ought to be diſcoverable in the fixed ſtars, ſuppoſing the
annual motion of the Earth, would be obſerved really and in
effect, a thing which I verily believe hath never as yet been done
by any; done, ſaid I? no, nor haply (as I ſaid before) by many
well underſtood how it ought to be done. Nor ſpeak I this at
randome, for I have heretofore ſeen a certain Manuſcript of
one of theſe Anti-Copernicans, which ſaid, that there would
ceſſarily follow, in caſe that opinion were true, a continual
ſing and falling of the Pole from ſix moneths to ſix moneths,
cording as the Earth in ſuch a time, by ſuch a ſpace as is the
meter of the grand Orb, retireth one while towards the North, and
another while towards the South; and yet it ſeemed to him
nable, yea neceſſary, that we, following the Earth, when we were
towards the North ſhould have the Pole more elevated than when
we are towards the South. In this very error did one fall that was
otherwiſe a very skilful Mathematician, & a follower of Copernic.

as Tycho relateth in his ^{*}Progymnaſma. pag 684. which ſaid, that he
had obſerved the Polar altitude to vary, and to differ in Summer
from what it is in Winter: and becauſe Tycho denieth the merit
1of the cauſe, but findeth no fault with the method of it; that
is, denieth that there is any mutation to be ſeen in the altitude of
the Pole, but doth not blame the inquiſition, for not being
ted to the finding of what is ſought, he thereby ſheweth, that he
alſo eſtecemed the Polar altitude varied, or not varied every ſix
moneths, to be a good teſtimony to diſprove or inferre the annual
motion of the Earth.
A ſtronomeys,
perhaps, have not
known what
pearances ought to
follow upon the
nual motion of the
Earth.
Copernicus
derſtood not ſome
things for want of
Inſtruments.
Tycho and
thers argue
gainſt the annual
motion, from the
invariable
tion of the Pole.
* Chriſiophoius
Rothmannus.
SIMP. In truth, Salviatus, my opinion alſo tells me, that the
ſame muſt neceſſarily enſue: for I do not think that you will
ny me, but that if we walk only 60. miles towards the North,
the Pole will riſe unto us a degree higher, and that if we move
60. miles farther Northwards, the Pole will be elevated to us a
degree more, &c. Now if the approaching or receding 60. miles
onely, make ſo notable a change in the Polar altitudes, what
alteration would follow, if the Earth and we with it, ſhould
be tranſported, I will not ſay 60. miles, but 60. thouſand miles
that way.
SALV. It would follow (if it ſhould proceed in the ſame
proportion) that the Pole ſhall be elevated a thouſand degrees.
See, Simplicius, what a long rooted opinion can do. Yea, by
reaſon you have fixed it in your mind for ſo many years, that it
is Heaven, that revolveth in twenty four hours, and not the
Earth, and that conſequently the Poles of that Revolution are in
Heaven, and not in the Terreſtrial Globe, cannot now, in an
hours time ſhake off this habituated conceipt, and take up the
contrary, fancying to your ſelf, that the Earth is that which
veth, only for ſo long time as may ſuffice to conceive of what
would follow, thereupon ſhould that lye be a truth. If the Earth
Simplicius, be that which moveth in its ſelf in twenty four hours,
in it are the Poles, in it is the Axis, in it is the Equinoctial, that
is, the grand Circle, deſcribed by the point, equidiſtant from the
Poles, in it are the inſinite Parallels bigger and leſſer deſcribed by
the points of the ſuperficies more and leſſe diſtant from the Poles,
in it are all theſe things, and not in the ſtarry Sphere, which, as
being immoveable, wants them all, and can only by the
tion be conceived to be therein, prolonging the Axis of the Earth
ſo far, till that determining, it ſhall mark out two points placed
right over our Poles, and the plane of the Equinoctial being
tended, it ſhall deſcribe in Heaven a circle like it ſelf. Now if the
true Axis, the true Poles, the true Equinoctial, do not change
in the Earth ſo long as you continue in the ſame place of the
Earth, and though the Earth be tranſported, as you do pleaſe,
yet you ſhall not change your habitude either to the Poles, or to
the circles, or to any other Earthly thing; and this becauſe, that
that tranſpoſition being common to you and to all Terreſtrial
1things; and that motion where it is common, is as if it never

were; and as you change not habitude to the Terreſtrial Poles
(habitude I ſay, whether that they riſe, or deſcend) ſo neither
ſhall you change poſition to the Poles imagined in Heaven;
wayes provided that by Celeſtial Poles we underſtand (as hath
been already defined) thoſe two points that come to be marked
out by the prolongation of the Terreſtrial Axis unto that length.
Tis true thoſe points in Heaven do change, when the Earths
ſportment is made after ſuch a manner, that its Axis cometh to
paſſe by other and other points of the immoveable Celeſtial
Sphere, but our habitude thereunto changeth not, ſo as that the
ſecond ſhould be more elevated to us than the firſt. If any one
will have one of the points of the Firmament, which do anſwer
to the Poles of the Earth to aſcend, and the other to deſcend,
he muſt walk along the Earth towards the one, receding from the
other, for the tranſportment of the Earth, and with it us our
ſelves, (as I told you before) operates nothing at all.
Motion where
it is common, is as
if it never were.
SAGR. Permit me, I beſeech you Salviatus, to make this a
little more clear by an example, which although groſſe, is
commodated to this purpoſe. Suppoſe your ſelf, Simplicius, to

be aboard a Ship, and that ſtanding in the Poope, or Hin-deck;
you have directed a Quadrant, or ſome other Aſtronomical
ſtrument, towards the top of the Top-gallant-Maſt, as if you
would take its height, which ſuppoſe it were v. gr. 40. degrees,

there is no doubt, but that if you walk along the ^{*} Hatches
wards the Maſt 25. or 30. paces; and then again direct the ſaid
Inſtrument to the ſame Top-Gallant-Top. You ſhall find its
vation to be greater, and to be encreaſed v. gr. 10. degrees; but
if inſtead of walking thoſe 25. or 30. paces towards the Maſt,
you ſtand ſtill at the Sterne, and make the whole Ship to move
thitherwards, do you believe that by reaſon of the 25. or 30.
paces that it had paſt, the elevation of the Top-Gallant-Top
would ſhew 10. degrees encreaſed?
An example
ted to prove that
the altitude of the
Pole ought not to
vary by means of
the Earths annual
motion.
* Corſia, the bank
or bench on which
ſlaves ſit in a
ly.
SIMP. I believe and know that it would not gain an hairs
breadth in the paſſing of 30. paces, nor of a thouſand, no nor of
an hundred thouſand miles; but yet I believe withal that
ing through the ſights at the Top and Top-Gallant, if I ſhould
find a fixed Star that was in the ſame elevation, I believe I ſay,
that, holding ſtill the Quadrant, after I had ſailed towards the
ſtar 60. miles, the eye would meet with the top of the ſaid
Maſt, as before, but not with the ſtar, which would be
ted to me one degree.
SAGR. Then you do not think that the ſight would fall upon
that point of the Starry Sphere, that anſwereth to the direction
of the Top-Gallant Top?
1
SIMP. No: For the point would be changed, and would be
beneath the ſtar firſt obſerved.
SAGR. You are in the right. Now like as that which in this
example anſwereth to the elevation of the Top-Gallant-Top, is
not the ſtar, but the point of the Firmament that lyeth in a right
line with the eye, and the ſaid top of the Maſt, ſo in the caſe
exemplified, that which in the Firmament anſwers to the Pole
of the Earth, is not a ſtar, or other fixed thing in the
ment; but is that point in which the Axis of the Earth
ed ſtreight out, till it cometh thither doth determine, which point
is not fixed, but obeyeth the mutations that the Pole of the
Earth doth make. And therefore Tycho, or who ever elſe that

did alledg this objection, ought to have ſaid that upon that
ſame motion of the Earth, were it true, one might obſerve ſome
difference in the elevation and depreſſion (not of the Pole, but)
of ſome fixed ſtar toward that part which anſwereth to our Pole.
Upon the
al motion of the
Earth, alteration
may enſue in
ſome fixed ſtar,
not in the Pole.
SIMP. I already very well underſtand the miſtake by them
committed; but yet therefore (which to me ſeems very great) of
the argument brought on the contrary is not leſſened,
ſing relation to be had to the variation of the ſtars, and not of
the Pole; for if the moving of the Ship but 60. miles, make a
fixed ſtar riſe to me one degree, ſhall I not find alike, yea and
very much greater mutation, if the Ship ſhould ſail towards the
ſaid ſtar for ſo much ſpace as is the Diameter of the Grand
Orb, which you affirm to be double the diſtance that is between
the Earth and Sun?
SAGR. Herein Simplicius, there is another fallacy, which,

truth is, you underſtand, but do not upon the ſudden think of
the ſame, but I will try to bring it to your remembrance: Tell
me therefore; if when after you have directed the Quadrant to
a fixed ſtar, and found v. g. its elevation to be 40. degrees,
you ſhould without ſtirring from the place, incline the ſide of
the Ouadrant, ſo as that the ſtar might remain elevated above
that direction, would you thereupon ſay that the ſtar had
red greater elevation?
The equivoke of
thoſe who believe
that in the annual
motion great
tations are to be
made about the
elevation of a
ed ſtar, is
ted.
SIMP. Certainly no: For the mutation was made in the
ſtrument and not in the Obſerver, that did change place,
ving towards the ſame.
SAGR. But if you ſail or walk along the ſurface of the
ſtrial Globe, will you ſay that there is no alteration made in the
ſaid Quadrant, but that the ſame elevarion is ſtill retained in
ſpect of the Heavens, ſo long as you your ſelf do not incline it,
but let it ſtand at its firſt conſtitution?
SIMP. Give me leave to think of it. I would ſay without
more ado, that it would not retain the ſame, in regard the
1greſſe I make is not in plano, but about the circumference of the
Terreſtrial Globe, which at every ſtep changeth inclination in
reſpect to Heaven, and conſequently maketh the ſame change
in the Inſtrument which is erected upon the ſame.
SAGR. You ſay very well: And you know withal, that by
how much the bigger that circle ſhall be upon which you move,
ſo many more miles you are to walk, to make the ſaid ſtar to
riſe that ſame degree higher; and that ſinally if the motion
wards the ſtar ſhould be in a right line, you ought to move yet
farther, than if it were about the circumference of never ſo
great a
The right line,
and circumference
of an infinite
cle, are the ſame
thing.
SALV. True: For in ſhort the circumference of an infinite
circle, and a right line are the ſame thing.
SAGR. But this I do not underſtand, nor as I believe, doth
Simplicius apprehend the ſame; and it muſt needs be concealed
from us under ſome miſtery, for we know that Salviatus never
ſpeaks at random, nor propoſeth any Paradox, which doth not
break forth into ſome conceit, not trivial in the leaſt. Therefore
in due time and place I will put you in mind to demonſtrate this,
that the right line is the ſame with the circumference of an
nite circle, but at preſent I am unwilling that we ſhould
rupt the diſcourſe in hand. Returning then to the caſe, I
poſe to the conſideration of Simplicius, how the acceſſion and
receſſion that the Earth makes from the ſaid fixed ſtar which is
neer the Pole can be made as it were by a right line, for ſuch is
the Diameter of the Grand Orb, ſo that the attempting to
gulate the elevation and depreſſion of the Polar ſtar by the
tion along the ſaid Diameter, as if it were by the motion about
the little circle of the Earth, is a great argument of but little
judgment.
SIMP. But we continue ſtill unſatisfied, in regard that the
ſaid ſmall mutation that ſhould be therein, would not be
ned; and if this be null, then muſt the annual motion about
the Grand Orb aſcribed to the Earth, be null alſo.
SAGR. Here now I give Salviatus leave to go on, who as I
believe will not overpaſſe the elevation and depreſſion of the
Polar ſtar or any other of thoſe that are fixed as null, although
not diſcovered by any one, and affirmed by Copernicus himſelf
to be, I will not ſay null, but unobſervable by reaſon of its
minuity.
SALV. I have already ſaid above, that I do not think that

any one did ever ſet himſelf to obſerve, whether in different times
of the year there is any mutation to be ſeen in the fixed ſtars, that
may have a dependance on the annual motion of the Earth, and
added withal, that I doubted leaſt haply ſome might never have
1underſtood what thoſe mutations are, and amongſt what ſtars
they ſhould be diſcerned; therefore it would be neceſſary that
we in the next place narrowly examine this particular. My

ving onely found written in general terms that the annual
on of the Earth about the Grand Orb, ought not to be
ted, becauſe it is not probable but that by means of the ſame
there would be diſcoverd ſome apparent mutation in the fixed
ſtars, and not hearing ſay what thoſe apparent mutations ought to
be in particular, and in what ſtars, maketh me very reaſonably
to infer that they who rely upon that general poſition, have not
underſtood, no nor poſſibly endeavoured to underſtand, how
the buſineſſe of theſe mutations goeth, nor what things thoſe
are which they ſay ought to be ſeen. And to this judgment I am

the rather induced, knowing that the annual motion aſcribed
by Copernicus to the Earth, if it ſhould appear ſenſible in the
Starry Sphere, is not to make apparent mutations equal in
ſpect to all the ſtars, but thoſe appearances ought to be made
in ſome greater, in others leſſer, and in others yet leſſer; and
laſtly, in others abſolutely nothing at all, by reaſon of the
vaſt magnitude that the circle of this annual motion is ſuppoſed
to be of. As for the mutations that ſhould b ſeen, they are of
two kinds, one is the ſaid ſtars changing apparent magnitude,
and the other their variation of altitudes in the Meridian. Upon
which neceſſarily followeth the mutation of riſings and ſettings,
and of their diſtances from the Zenith, &c.
Enquiry is made
what mutations, &
in what ſtars, are to
be diſcovered, by
means of the
nual motion of the
Earth.
Aſtronomers
ving omitted to
ſtance what
rations thoſe are
that may be
ved from the
nual motion of the
Earth, do thereby
teſtifie that they
never rightly
derſtood the ſame.
The mutations
of the fixed ſtars
ought to be in ſome
greater, in others
leſſer, and in others
nothing at all.
SAGR. Methinks I ſee preparing for me ſuch a skean of theſe
revolutions, that I wiſh it may never be my task to diſ-intangle
them, for to confeſſe my infirmity to Salviatus, I have
times thought thereon, but could never find the ^{*} Lay-band of

it, and I ſpeak not ſo much of this which pertains to the fixed
ſtars, as of another more terrible labour which you bring to my
remembrance by maintaining theſe Meridian Altitudes, Ortive
Latitudes and diſtances from the Vertex, &c. And that which

puzzleth my brains, ariſeth from what I am now about to tell
you. Copernicus ſuppoſeth the Starry Sphere immoveable, and
the Sun in the centre thereof immoveable alſo. Therefore
ry mutation which ſeemeth unto us to be made in the Sun or in
the fixed ſtars, muſt of neceſſity befall the Earth and be ous.
But the Sun riſeth and declineth in our Meridian by a very great
arch of almoſt 47. degrees, and by arches yet greater and
greatet, varieth its Ortive and Occidual Latitudes in the oblique

Horizons. Now how can the Earth ever incline and elevate ſo
notably to the Sun, and nothing at all to the fixed ſtars, or ſo
little, that it is not to be perceived? This is that knot which
could never get thorow my ^{*} Loom-Combe; and if you ſhall
1untie it, I ſhall hold you for more than an Alexander.
* Bandola that
end of a skeen
where with
wives faſten their
hankes of yarn,
thread or ſilk.
The grand
ficulty in
nicus his Doctrine,
is that which
cerns the
mena of the Sun
and fixed ſtars.
* Pettine, it is
the ſtay in a
vets Loom, that
permitteth no knot
or ſnarle to paſſe
it, called by them
the Combe of the
Loom.
SALV. Theſe are ſcruples worthy of the ingenuity of
dus, and this doubt is ſo intricate, that even Copernicus himſelf
almoſt deſpaired of being able to explain the ſame, ſo as to
render it intelligible, which we ſee as well by his own confeſſion
of its obſcurity, as alſo by his, at two ſeveral times, taking two
different wayes to make it out. And, I ingenuouſly confeſſe that
I underſtood not his explanation, till ſuch time as another
thod more plain and manifeſt, had rendred it intelligible; and
yet neither was that done without a long and laborious
tion of my thoughts to the ſame.
SIMP. Ariſtotle ſaw the ſame ſcruple, and makes uſe

of to oppoſe certain of the Ancients, who held that the Earth
was a Planet; againſt whom he argueth, that if it were ſo, it
would follow that it alſo, as the reſt of the Planets, ſhould have a
plurality of motions, from whence would follow theſe
ons in the riſings and ſettings of the fixed ſtars, and likewiſe in
the Meridian Altitudes. And in regard that he propoundeth the
difficulty, and doth not anſwer it, it muſt needs be, if not
poſſible, at leaſt very difficult to be reſolved.
Ariſtotles
ment againſt the
Ancients, who held
that the Earth
was a Planet.
SALV. The ſtreſſe and ſtrength of the knot rendereth the
ſolution thereof more commendable and admirable; but I do
not promiſe you the ſame at this time, and pray you to diſpenſe
with me therein till too morrow, and for the preſent we will go
conſidering and explaining thoſe mutations and differences that
by means of the annual motion ought to be diſcerned in the
ed ſtars, like as even now we ſaid, for the explication whereof
certain preparatory points offer themſelves, which may
tate the anſwer to the grand objection. Now reaſſuming the
two motions aſcribed to the Earth (two I ſay, for the third is
no motion, as in its place I will declare) that is the annual and

diurnal, the firſt is to be underſtood to be made by the centre of
the Earth in or about the circumference of the grand Orb, that
is of a very great circle deſcribed in the plain of the fixed and
immutable Ecliptick; the other, namely the diurnal, is made
by the Globe of the Earth in it ſelf about its own centre, and
own Axis, not erect, but inclined to the Plane of the Ecliptick,
with the inclination of 23. degrees and an half, or thereabouts,
the which inclination is maintained all the year about, and that
which ought eſpecially to be obſerved, is alwayes ſituate
wards the ſame point of Heaven: in ſo much that the Axis of the

diurnal motion doth alwayes remain parallel to it ſelf; ſo that
if we imagine that ſame Axis to be continued out until it reach
the fixed ſtars, whilſt the centre of the Earth is encircling the
whole Ecliptick in a year, the ſaid Axis deſcribeth the
1ficies of an oblique Cylinder, which hath for one of its baſes
the ſaid annual circle, and for the other a like circle
rily deſcribed by its extremity, or, (if you will) Pole, amongſt
the fixed ſtars. And this ſame cylinder is oblique to the Plane of
the Ecliptick, according to the inclination of the Axis that
ſcribeth it, which we have ſaid to be 23 degrees and an half,
the which continuing perpetually the ſame (ſave onely, that in
many thouſands of years it maketh ſome very ſmall mutation,
which nothing importeth in our preſent buſineſſe) cauſeth that

the Terreſtrial Globe doth never more incline or elevate, but
ſtill conſerveth the ſame ſtate without mutation. From whence
enſueth, that as to what pertaineth to the mutations to be
ſerved in the fixed ſtars dependant on the ſole annual motion,
the ſame ſhall happen to any point whatſoever of the Earths
ſurface, as befalleth unto the centre of the Earth it ſelf; and
therefore in the preſent explanations we will make uſe of the
centre, as if it were any whatſoever point of the ſuperficies.
And for a more facile underſtanding of the whole, let us deſign

the ſame in lineal figures: And firſt of all let us deſcribe in the
Plane of the Ecliptick the circle A N B O [in Fig. 7.] and let
us underſtand the points A and B, to be the extreams towards
the North and South; that is, the beginning of [or entrance into]
Cancer or Capricorn, and let us prolong the Diameter A B,
determinately by D and C towards the Starry Sphere. I ſay
now in the firſt place, that none of the fixed ſtars placed in the
Ecliptick, ſhall ever vary elevation, by reaſon of any
ever mutation made by the Earth along the ſaid Plane of the
Ecliptick, but ſhall alwayes appear in the ſame ſuperficies,
though the Earth ſhall approach and recede as great a ſpace as is
that of the diameter of the Grand Orb, as may plainly be
ſeen in the ſaid figure. For whether the Earth be in the point
A or in B, the ſtar C alwayes appeareth in the ſame line A B C;
although the diſtance B C, be leſſe than A C, by the whole
diameter A B. The moſt therefore that can be diſcovered in the
ſtar C, and in any other placed in the Ecliptick, is the
mented or diminiſhed apparent magnitude, by reaſon of the
proximation or receſſion of the Earth.
The annual
tion made by the
centre of the Earth
under the
tick and the
nal motion made
by the Earth about
its own centre.
The axis of the
Earth continueth
alwayes parallel to
it ſelf, and
beth a
cal ſuperficies,
clining to the
grand Orb.
The Orb of the
Earth never
neth, but is
mutably the ſame.
The fixed ſtars
placed in the
cliptick never
vate nor deſcend,
on account of the
annual motion, but
yet approach and
recede.
SAGR. Stay a while I pray you, for I meet with a certain
ſcruple, which much troubleth me, and it is this: That the ſtar
C may be ſeen by the ſame line A B C, as wel when the Earth
is in A, as when it is in B, I underſtand very well, as alſo
thermore I apprehend that the ſame would happen in all the

points of the line A B, ſo long as the Earth ſhould paſſe from A
to B by the ſaid line; but it paſſing thither, as is to be ſuppoſed,
by the arch A N B, it is manifeſt that when it ſhall be in the
1point N, and in any other except thoſe two A and B, the ſaid
ſtar ſhall no longer be obſerved in the line A B; but in others.
So that, if the appearing under ſeveral lines ought to cauſe
apparent mutations, ſome difference muſt needs appear in
this caſe. Nay more, I will ſpeak it with that Philoſophical
freedom, which ought to be allowed amongſt Philoſophick
friends, methinks that you, contradicting your ſelf, deny that
now, which but even now to our admiration, you proved to be
really true, and conſiderable; I mean that which happeneth in
the Planets, and particularly in the three ſuperiour ones, that
being conſtantly in the Ecliptick, or very near unto it, do not
onely ſhew themſelves one while near unto us, and another
while remote, but ſo deformed in their regular motions, that
they ſeem ſometimes immoveable, and ſometimes many
grees retrograde; and all upon no other occaſion than the
nual motion of the Earth.
Objections againſt
the Earths annual
motion taken from
the fixed stars
placed in the
cliptick.
SALV. Though by a thouſand accidents I have been
fore aſſured of the wittineſſe of Sagredus, yet I had a deſire by
this one experiment more to aſcertain me of what I may expect
from his ingenuity, and all this for my own intereſt, for in caſe
my Propoſitions ſtand but proof againſt the hammer and
nace of his judgment, I ſhall be confident that they will abide

the ^{*} teſt of all Touch-ſtones. I ſay therefore that I had
poſely diſſembled this objection, but yet not with any intent to
deceive you, and to put any falſhood upon you, as it might
have happened if the objection by me diſguiſed, and by you
ver-lookt, had been the ſame in effect as it ſeemed to be in
pearance, that is, really valid and concluſive; but it is not ſo;
nay I rather ſuſpect that to try me, you make as if you did not
ſee its nullity. But I will herein be too hard for you, and force
from your tongue, that which you would ſo artificially conceal;
and therefore tell me, what that thing ſhould be, whereby you
come to know the ſtation and retrogradation of the Planets,
which is derived from the annual motion, aud which is ſo great,
that at leaſt ſome foot-ſteps of ſuch an effect ought to appear in
the ſtars of the Ecliptick?
* Or will prove
of good alloy.
SAGR. This demand of yours containeth two queſtions, to
which it is neceſſary that I make reply; the firſt relates to the
imputation which you lay upon me of a Diſſembler; the other
concerneth that which may appear in the ſtars, &c. As to the
firſt, I will ſay with your permiſſion, that it is not true, that I
have diſſembled my knowing the nullity of that objection; and
to aſſure you of the ſame, I now tell you that I very well
ſtand the nullity thereof.
SALV. But yet I do not underſtand how it can be, that you
1ſpake not friendly, when you ſaid you did not know that ſame
fallacy which you now confeſſe that you know very well.
SAGR. The very confeſſion of knowing it may aſſure you
that I did not diſſemble, when I ſaid that I did not underſtand it;
for if I had had a mind, and would diſſemble, who could
der me from continuing in the ſame ſimulation, and denying ſtill
that I underſtand the fallacy? I ſay therefore that I underſtood
not the ſame, at that time, but that I do now at this preſent
prehend it, for that you have prompted my intellect, firſt by
telling me reſolutely that it is null, and then by beginning to
queſtion me ſo at large what thing that might be, whereby I
might come to know the ſtation and retrogradation of the

nets; and becauſe this is known by comparing them with the
ed ſtars, in relation to which, they are ſeen to vary their
tions, one while towards the Weſt, and another towards the
Eaſt, and ſometimes to abide immoveable; and becauſe there
is not any thing above the Starry Sphere, immenſely more remote
from us, and viſible unto us, wherewith we may compare our
fixed ſtars, therefore we cannot diſcover in the fixed ſtars any
foot-ſteps of what appeareth to us in the Planets. This I believe
is the ſubſtance of that which you would force from me.
The ſtation,
rection and
gradation of the
Planets is known,
in relation to the
fixed ſtars.
SALV. It is ſo, with the addition moreover of your

rable ingenuity; and if with half a word I did open your eyes,
you by the like have remembred me that it is not altogether
poſſible, but that ſometime or other ſomething obſervable may
be found amongſt the fixed ſtars, by which it may be gathered
wherein the annual converſion reſides, ſo as that they alſo no
leſſe than the Planets and Sun it ſelf, may appear in judgment to
bear witneſſe of that motion, in favour of the Earth; for I do not
think that the ſtas are ſpread in a ſpherical ſuperficies equally
mote from a common centre, but hold, that their diſtances from
us are ſo various, that ſome of them may be twice and thrice as
remote as others; ſo that if with the Teleſcope one ſhould
ſerve a very ſmall ſtar neer to one of the bigger, and which
therefore was very exceeding high, it might happen that ſome
ſenſible mutation might fall out between them, correſpondent
to that of the ſuperiour Planets. And ſo much ſhall ſerve to have
ſpoken at this time touching the ſtars placed in the Ecliptick.

Let us now come to the fixed ſtars, placed out of the Ecliptick,
and let us ſuppoſe a great circle erect upor [i. e. at right angles
to] the Plane of the ^{*} ſame; and let it, for example, be a cir­
cle that in the Starry Sphere anſwers to the Solſtitial Colure,

and let us mark it C E H [in Fig. 8.] which ſhall happen to be
withal a Meridian, and in it we will take a ſtar without the
tick, which let be E. Now this ſtar will indeed vary its
1on upon the Earths motion; for from the Earth in A it ſhall be
ſeen according to the ray A E, with the elevation of the angle
E A C; but from the Earth placed in B, it ſhall be ſeen
cording to the ray B E, with the elevation of the angle E B C,
bigger than the other E A C, that being extern, and this
tern and oppoſite in the triangle E A B, the diſtance therefore
of the ſtar E from the Ecliptick, ſhall appear changed; and
likewiſe its altitude in the Meridian ſhall become greater in the
poſition B, than in the place A, according as the angle E B C
exceeds the angle E A C, which exceſſe is the quantity of the
angle A E B: For in the triangle E A B, the ſide A B being
continued to C, the exteriour angle E B C (as being equal to
the two interiour and oppoſite E and A) exceedeth the ſaid
gle A, by the quantity of the angle E. And if we ſhould take
another ſtar in the ſame Meridian, more remote from the
ptick, as for inſtance the ſtar H, the diverſity in it ſhall be
greater by being obſerved from the two ſtations A and B,
ding as the angle A H B is greater than the other E; which
gle ſhall encreaſe continually according as the obſerved ſtar ſhall
be farther and farther from the Ecliptick, till that at laſt the
greateſt mutation will appear in that ſtar that ſhould be placed in
the very Pole of the Ecliptick. As for a full underſtanding
of we thus demonſtrate. Suppoſe the diameter of the Grand
Orb to be A B, whoſe centre [in the ſame Figure] is G, and
let it be ſuppoſed to be continued out as far as the Starry Sphere
in the points D and C, and from the centre G let there be erected
the Axis of the Ecliptick G F, prolonged till it arrive at the ſaid
Sphere, in which a Meridian D F C is ſuppoſed to be deſcribed,
that ſhall be perpendicular to the Plane of the Ecliptick; and
in the arch F C any points H and E, are imagined to be taken,
as places of fixed ſtars: Let the lines F A, F B, A H, H G,
H B, A E, G E, B E, be conjoyned. And let the angle of
ference, or, if you will, the Parallax of the ſtar placed in the
Pole F, be A F B, and let that of the ſtar placed in H, be the
angle A H B, and let that of the ſtar in E, be the angle
A E B. I ſay, that the angle of difference of the Polar ſtar F, is
the greateſt, and that of the reſt, thoſe that are nearer to the
greateſt are bigger than the more remote; that is to ſay, that the
angle F is bigger than the angle H, and this bigger than the angle
E. Now about the triangle F A B, let us ſuppoſe a circle to be
ſcribed. And becauſe the angle F is acute, (by reaſon that its baſe
AB is leſſe than the diameter DC, of the ſemicircle D F C) it ſhall
be placed in the greater portion of the circumſcribed circle cut
by the baſe A B. And becauſe the ſaid A B is divided in the
midſt, and at right angles by F G, the centre of the
1bed circle ſhall be in the line F G, which let be the point I; and
becauſe that of ſuch lines as are drawn from the point G, which
is not the centre, unto the circumference of the circumſcribed
circle, the biggeſt is that which paſſeth by the centre, G F ſhall
be bigger than any other that is drawn from the point G, to the
circumference of the ſaid circle; and therefore that
rence will cut the line G H (which is equal to the line G F) and
cutting G H, it will alſo cut A H. Let it cut it in L, and
joyn the line L B. Theſe two angles, therefore, A F B and A L B
ſhall be equal, as being in the ſame portion of the circle
cumſcribed. But A L B external, is bigger than the internal H;
therefore the angle F is bigger than the angle H. And by the
ſame method we might demonſtrate the angle H to be bigger
than the angle E, becauſe that of the circle deſcribed about the
triangle A H B, the centre is in the perpendicular G F, to which
the line G H is nearer than the line G E, and therefore the
cumference of it cutteth G E, and alſo A E, whereupon the
poſition is manifeſt. We will conclude from hence, that the
ference of appearance, (which with the proper term of art, we
might call the Parallax of the fixed ſtars) is greater, or leſſe,
cording as the Stars obſerved are more or leſſe adjacent to the
Pole of the Ecliptick, ſo that, in concluſion of thoſe Stars that
are in the Ecliptick it ſelf, the ſaid diverſity is reduced to nothing.
In the next place, as to the Earths acceſſion by that motion to,

or receſſion from the Stars, it appeareth to, and recedeth from
thoſe that are in the Ecliptick, the quantity of the whole
ter of the grand Orb, as we did ſee even now, but that acceſſion
or receſſion to, or from the ſtars about the Pole of the Ecliptick,
is almoſt nothing; and in going to and from others, this
rence groweth greater, according as they are neerer to the
tick. We may, in the third place, know, that the ſaid difference

of Aſpect groweth greater or leſſer, according as the Star
ved ſhall be neerer to us, or farther from us. For if we draw
nother Meridian, leſſe diſtant from the Earth; as for example,
this D F I [in Fig. 7.] a Star placed in F, and ſeen by the ſame
ray A F E, the Earth being in A, would, in caſe it ſhould be
ſerved from the Earth in B, appear according to the ray B F, and
would make the angle of difference, namely, B F A, bigger
than the former A E B, being the exteriour angle of the
gle B F E.
An Indice in
the fixed ſtars like
to that which is
ſeen in the
nets, is an
ment of the Earths
annual motion.
The fixed ſtars
without the
tick elevate and
deſcend more or
leſſe, according to
their diſtance from
the ſaid Ecliptick.
* i. e. of the
cliptick.
The Earth
proacheth or
deth from the
ed ſtars of the
cliptick, the
tity of the
ter of the Grand
Orb.
The ſtars
er to us make
greater differences
than the more
more.
SAGR. With great delight, and alſo benefit have I heard
your diſcourſe; and that I may be certain, whether I have

ly underſtood the ſame, I ſhall give you the ſumme of the
cluſions in a few words. As I take it, you have explained to us
the different appearances, that by means of the Earths annual
1tion, may be by us obſerved in the fixed ſtars to be of two
kinds: The one is, that of their apparent magnitudes varied,
cording as we, tranſported by the Earth, approach or recede
from the ſame: The other (which likewiſe dependeth on the
ſame acceſſion and reeeſſion) their appearing unto us in the
ſame Meridian, one while more elevated, and another while leſſe.
Moreover, you tell us (and I underſtand it very well) that the
one and other of theſe mutations are not made alike in all the
ſtars, but in ſome greater, and in others leſſer, and in others not
at all. The acceſſion and receſſion whereby the ſame ſtar ought
to appear, one while bigger, and another while leſſer, is
ble, and almoſt nothing in the ſtars neer unto the pole of the
cliptick, but is greateſt in the ſtars placed in the Ecliptick it ſelf,
and indifferent in the intermediate: the contrary happens in the
other difference, that is, the elevation or depreſſion of the ſtars
placed in the Ecliptick is nothing at all, greateſt in thoſe neereſt
to the Pole of the ſaid Ecliptick, and indifferent in the
diate. Beſides, both theſe differences are more ſenſible in the
Stars neereſt to us, in the more remote leſſe ſenſible, and in
thoſe that are very far diſtant wholly diſappear. This is, as to
what concerns my ſelf; it remaineth now, as I conceive, that
ſomething be ſaid for the ſatisfaction of Simplicius, who, as I
believe, will not eaſily be made to over-paſſe thoſe differences,
as inſenſible that are derived from a motion of the Earth ſo vaſt,
and from a mutation that tranſports the Earth into places twice
as far diſtant from us as the Sun.
The Epilogue of
the Phænomena
of the fixed ſtars
cauſed by the
nual motion of the
Earth.
SIMP. Truth is, to ſpeak freely, I am very loth to confeſſe, that
the diſtance of the fixed Stars ought to be ſuch, that in them the
fore-mentioned differences ſhould be wholly imperceptible.
SALV. Do notthrow your ſelf into abſolute deſpair,
cius, for there may perhaps yet ſome qualification be found for
your difficulties. And firſt, that the apparent magnitude of the
ſtars is not ſeen to make any ſenſible alteration, ought not to be
judged by you a thing improbable, in regard you ſee the gueſſes
of men in this particular to be ſo groſſely erroneous, eſpecially in
looking upon ſplendid objects; and you your ſelf beholding
v. g. a lighted Torch at the diſtance of 200 paces, if it

proach nearer to you 3. or 4. yards, do you think that it will
ſhew any whit encreaſed in magnitude? I for my part ſhould
not perceive it certainly, although it ſhould approach 20. or
30. yards nearer; nay it hath ſometimes happened that in ſeeing
ſuch a light at that diſtance I know not how to reſolve whether
it came towards me, or retreated from me, when as it did in
reality approach nearer to me. But what need I ſpeak of this?
If the ſelf ſame acceſſion and receſſion (I ſpeak of a diſtance
1twice as great as that from the Sun to us) in the ſtar of Saturn is
almoſt totally imperceptible, and in Jupiter not very
ble, what ſhall we think of the fixed ſtars, which I believe you
will not ſcruple to place twice as far off as Saturn? In Mars,
which for that it is nearer to us -------
In objects far
remote, and
nous, a ſmall
proach or receſſion
is imperceptible.
SIMP. Pray Sir, put your ſelf to no farther trouble in this
particular, for I already conceive that what hath been ſpoken
touching the unaltered apparent magnitude of the fixed ſtars may
very well come to paſſe, but what ſhall we ſay of the other
ficulty that proceeds from not perceiving any variation in the
mutation of aſpect?
SALV. We will ſay that which peradventure may ſatisfie
you alſo in this particular. And to make ſhort, would you not
be ſatisfied if there ſhould be diſcovered in the ſtars face
tions that you think ought to be diſcovered, in caſe the annual
motion belonged to the Earth?
SIMP. I ſhould ſo doubtleſſe, as to what concerns this
ticular.
SALV. I could wiſh you would ſay that in caſe ſuch a

rence were diſcovered, nothing more would remain behind, that
might render the mobility of the Earth queſtionable. But
though yet that ſhould not ſenſibly appear, yet is not its
bility removed, nor its immobility neceſſarily proved, it being
poſſible, (as Copernicus affirmeth) that the immenſe diſtance of
the Starry Sphere rendereth ſuch very ſmall Phænomena
vable; the which as already hath been ſaid, may poſſibly not
have been hitherto ſo much as ſought for, or if ſought for, yet
not ſought for in ſuch a way as they ought, to wit, with that

exactneſſe which to ſo minute a punctuality would be neceſſary;
which exactneſſe is very difficult to obtain, as well by reaſon of the
deficiency of Aſttonomical Inſtruments, ſubject to many
tions, as alſo through the fault of thoſe that manage them with leſs
diligence then is requiſite. A neceſſary argument how little
dit is to be given to thoſe obſervations may be deduced from the
differences which we find amongſt Aſtronomers in aſſigning the
places, I will not ſay, of the new Stars or Comets, but of the fixed
ſtars themſelves, even to the altitudes of the very Poles, in
which, moſt an end, they are found to differ from one another
many minutes. And to ſpeak the truth, who can in a Quadrant,
or Sextant, that at moſt ſhall have its ſide ^{*} 3. or 4. yards long,

aſcertain himſelf in the incidence of the perpendicular, or in the
direction of the ſights, not to erre two or three minutes, which
in its circumference ſhall not amount to the breadth of a grain of
^{*}Mylet? Beſides that, it is almoſt impoſſible, that the Inſtrument

ſhould be made, and kept with abſolute exactneſſe. Ptolomey
1
ſheweth his diſtruſt of a Spherical Inſtrument compoſed by
chimedes hiſmelf to take the Suns ingreſſion into the

If in the fixed
ſtars one ſhould
diſcover any
nual mutation, the
motion of the
Earth would be
undeniable.
It is proved what
ſmall credit is to be
given to
mical Inſtruments
in minute
tions.
* Braceia Italian.
* Or Mill.
Ptolomy did not
truſt to an
ment made by
chimedes.
Inſtruments of
Tycho made with
great expence.
SIMP. But if the Inſtruments be ſo ſuſpitious, and the
vations ſo dubious, how can we ever come to any certainty of
things, or free our ſelves from miſtakes? I have heard ſtrange
things of the Inſtruments of Tycho made with extraordinary coſt,
and of his ſingular diligence in obſervations.
SALV. All this I grant you; but neither one nor other of
theſe is ſufficient to aſcertain us in a buſineſſe of this importance.

I deſire that we may make uſe of Inſtruments greater by far, and
by far certainer than thoſe of Tycho, made with a very ſmall
charge; the ſides of which are of 4. 6. 20. 30. and 50. miles, ſo

as that a degree is a mile broad, a minute prim. 50 ^{*} yards, a
ſecond but little leſſe than a yard, and in ſhort we may without
a farthing expence procure them of what bigneſſe we pleaſe. I

being in a Countrey Seat of mine near to Florence, did plainly
obſerve the Suns arrival at, and departure from the Summer
Solſtice, whilſt one Evening at the time of its going down it
peared upon the top of a Rock on the Mountains of Pictrapana,
about 60. miles from thence, leaving diſcovered of it a ſmall
ſtreak or filament towards the North, whoſe breadth was not
the hundredth part of its Diameter; and the following Evening
at the like ſetting, it ſhew'd ſuch another part of it, but notably
more ſmall, a neceſſary argument, that it had begun to recede
from the Tropick; and the regreſſion of the Sun from the firſt to
the ſecond obſervation, doth not import doubtleſſe a ſecond

nute in the Eaſt. The obſervation made afterwards with an
quiſite Teleſcope, and that multiplyeth the Diſcus of the Sun
more than a thouſand times, would prove eaſie, and with all
delightful. Now with ſuch an Inſtrument as this, I would have
obſervations to be made in the fixed ſtars, making uſe of ſome
of thoſe wherein the mutation ought to appear more
ous, ſuch as are (as hath already been declared) the more
mote from the Ecliptick, amongſt which the Harp a very great
ſtar, and near to the Pole of the Ecliptick, would be very
per in Countries far North, proceeding according to the
ner that I ſhall ſhew by and by, but in the uſe of another ſtar;
and I have already fancied to my ſelf a place very well adapted
for ſuch an obſervation. The place is an open Plane, upon
which towards the North there riſeth a very eminent Mountain,
in the apex or top whereof is built a little Chappel, ſituate Eaſt
and Weſt, ſo as that the ridg of its Roof may interſect at right
angles, the meridian of ſome building ſtanding in the Plane. I
will place a beam parallel to the ſaid ridg, or top of the Roof,
1and diſtant from it a yard or thereabouts. This being placed, I
will ſeek in the Plain the place from whence one of the ſtars of
Charls's Waine, in paſſing by the Meridian, cometh to hide it
ſelf behind the beam ſo placed, or in caſe the beam ſhould not
be ſo big as to hide the ſtar, I will finde a ſtation where one
may ſee the ſaid beam to cut the ſaid ſtar into two equal parts;
an effect that with an ^{*} exquiſite Teleſcope may be perfectly
diſcerned. And if in the place where the ſaid accident is
ed, there were ſome building, it will be the more commodious;
but if not, I will cauſe a Pole to be ſtuck very faſt in the
ground, with ſome ſtanding mark to direct where to place the
eye anew, when ever I have a mind to repeat the obſervation.
The firſt of which obſervations I will make about the Summer
Solſtice, to continue afterwards from Moneth to Moneth, or
when I ſhall ſo pleaſe, to the other Solſtice; with which
vation one may diſcover the elevation and depreſſion of the ſtar,
though it be very ſmall. And if in that operation it ſhall
pen, that any mutation ſhall diſcover it ſelf, what and how great
benefit will it bring to Aſtronomy? Seeing that thereby, beſides
our being aſſured of the annual motion, we may come to know
the grandure and diſtance of the ſame ſtar.
What
ments are apt for
moſt exact
vation.
* Italian braces.
An exquiſite
obſervation of the
approach and
parture of the Sun
from the Summer
Solſtice.
A place
modated for the
obſervation of the
fixed ſtars, as to
what concers the
annual motion of
the Earth.
SAGR. I very well comprehend your whole proceedings;
and the operation ſeems to me ſo eaſie, and ſo commodious for
the purpoſe, that it may very rationally be thought, that either
Copernicus himſelf, or ſome other Aſtronomer had made trial
of it.
SALV. But I judg the quite contrary, for it is not probable,
that if any one had experimented it, he would not have
tioned the event, whether it fell out in favour of this, or that
opinion; beſides that, no man that I can find, either for this,
or any other end, did ever go about to make ſuch an
on; which alſo without an exact Teleſcope could but badly be
effected.
SIMP. I am fully ſatisfied with what you ſay. But ſeeing
that it is a great while to night, if you defire that I ſhall paſſe
the ſame quietly, let it not be a trouble to you to explain unto
us thoſe Problems, the declaration whereof you did even now
requeſt might be deferred until too morrow. Be pleaſed to grant
us your promiſed indulgence, and, laying aſide all other
ſes, proceed to ſhew us, that the motions which Copernicus aſſigns
to the Earth being taken for granted, and ſuppoſing the Sun
and fixed ſtars immoveable, there may follow the ſame
dents touching the elevations and depreſſions of the Sun,
ing the mutations of the Seaſons, and the inequality of dayes
and nights, &c. in the ſelf ſame manner, juſt as they are with
1facility apprehended in the Prolomaick Syſteme.
SALV. I neither ought, nor can deny any thing that Sagredus
ſhall requeſt: And the delay by me deſired was to no other end,
ſave only that I might have time once again to methodize thoſe
prefatory points, in my fancy, that ſerve for a large and plain
claration of the manner how the forenamed accidents follow, as
well in the Copernican poſition, as in the Ptolomaick: nay, with

much greater facility and ſimplicity in that than in this. Whence
one may manifeſtly conceive that Hypotheſis to be as eaſie to be
effected by nature, as difficult to be apprehended by the
ſtanding: yet nevertheleſſe, I hope by making uſe of another

kind of explanation, than that uſed by Copernicus, to render
wiſe the apprehending of it ſomewhat leſſe obſcure. Which
that I may do, I will propoſe certain ſuppoſitions of themſelves
known and manifeſt, and they ſhall be theſe that follow.
The
can Syſteme
cult to be
ſtood, but eaſie to
be effected.
Neceſſary
poſitions for the
better conceiving
of the conſequences
of the Earths
tion.
Firſt, I ſuppoſe that the Earth is a ſpherical body, turning
round upon its own Axis and Poles, and that each point aſſigned
in its ſuperficies, deſcribeth the circumference of a circle,
er or leſſer, according as the point aſſigned ſhall be neerer or
farther from the Poles: And that of theſe circles the greateſt is
that which is deſcribed by a point equidiſtant from the ſaid Poles;
and all theſe circles are parallel to each other; and Parallels we
will call them.
Secondly, The Earth being of a Spherical Figure, and of an
pacous ſubſtance, it is continually illuminated by the Sun,
ding to the half of its ſurface, the other half remaining obſcure,
and the boundary that diſtinguiſheth the illuminated part from
the dark being a grand circle, we will call that circle the
nator of the light.
Thirdly, If the Circle that is terminator of the light ſhould
paſſe by the Poles of the Earth, it would cut (being a grand
and principal circle) all the parallels into equal parts; but not
paſſing by the Poles, it would cut them all in parts unequal,
cept only the circle in the middle, which, as being a grand circle
will be cut into equal parts.
Fourthly, The Earth turning round upon its own Poles, the
quantities of dayes and nights are termined by the arches of the
Parallels, interſected by the circle, that is, the terminator of the
light, and the arch that is ſcituate in the illuminated Hemiſphere
preſcribeth the length of the day, and the remainer is the
tity of the night.
Theſe things being preſuppoſed, for the more clear

ſtanding of that which remaines to be ſaid, we will lay it down
in a Figure. And firſt, we will draw the circumference of a
circle, that ſhall repreſent unto us that of the grand Orb
1bed in the plain of the Ecliptick, and this we will divide into
four equal parts with the two diameters Capricorn Cancer, and
Libra Aries, which, at the ſame time, ſhall repreſent unto us the
four Cardinal points, that is, the two Solſtices, and the two
quinoctials; and in the centre of that circle we will place the
Sun O, fixed and immoveable.
A plain Scheme
repreſenting the
Copernican
theſis, and its
ſequences.
20[Figure 20]
Let us next draw about the four points, Capricorn, Cancer,
Libra and Aries, as centres, four equal circles, which repreſent
unto us the Earth placed in them at four ſeveral times of the
year. The which, with its centre, in the ſpace of a year, paſſeth
through the whole circumference, Capricorn, Aries, Cancer,
bra, moving from Eaſt to Weſt, that is, according to the order
of the Signes. It is already manifeſt, that whilſt the Earth is in
Capricorn, the Sun will appear in Cancer, and the Earth moving

along the arch Capricorn Aries, the Sun will ſeem to move along
the arch Cancer Libra, and in ſhort, will run thorow the Zodiack
according to the order of the Signes, in the ſpace of a year; and
by this firſt aſſumption, without all queſtion, full ſatisfaction is
given for the Suns apparent annual motion under the Ecliptick.
Now, coming to the other, that is, the diurnal motion of the
Earth in it ſelf, it is neceſſary to eſtabliſh its Poles and its Axis,
the which muſt be underſtood not to be erect perpendicularly
upon the plain of the Ecliptick, that is, not to be parallel to the
Axis of the grand Orb, but declining from a right angle 23
grees and an half, or thereabouts, with its North Pole towards
1the Axis of the grand Orb, the Earths centre being in the
tial point of Capricorn. Suppoſing therefore the Terreſtrial
Globe to have its centre in the point Capricorn, we will deſcribe
its Poles and Axis A B, inclined upon the diameter Capricorn
Cancer 23 degrees and an half; ſo that the angle A Capricorn
Cancer cometh to be the complement of a Quadrant or Radius,
that is, 66 degrees and an half; and this inclination muſt be
derſtood to be immutable, and we will ſuppoſe the ſuperiour
Pole A to be Boreal, or North, and the other Auſtral, or South.
Now imagining the Earth to revolve in it ſelf about the Axis A B
in twenty four hours, from Weſt to Eaſt, there ſhall by all the
points aſſigned in its ſuperſicies, be circles deſcribed parallel to
each other. We will draw, in this firſt poſition of the Earth,
the greateſt C D, and thoſe two diſtant from it gr. 23. and an
half, E F above, and G M beneath, and the other two extream
ones I K and L M remote, by thoſe intervals from the Poles A
and B; and as we have marked theſe five, ſo we may imagine
numerable others, parallel to theſe, deſcribed by the
ble points of the Terreſtrial ſurface. Next let us ſuppoſe the
Earth, with the annual motion of its centre, to transferre it ſelf
into the other places already marked; but to paſſe thither in ſuch
a manner, that its own Axis A B ſhall not only not change
nation upon the plain of the Ecliptick, but ſhall alſo never vary
direction; ſo that alwayes keeping parallel to it ſelf, it may
continually tend towards the ſame part of the Univerſe, or, if
you will, of the Firmament, whereas, if we do but ſuppoſe it
prolonged, it will, with its extream termes, deſigne a Circle
rallel and equal to the grand Orb, Libra Capricorn Aries Cancer,
as the ſuperiour baſe of a Cylinder deſcribed by it ſelf in the
nual motion above the inferiour baſe, Libra Capricorn Aries
Cancer. And therefore this immutability of inclination
nuing, we will deſign theſe other three figures about the centres
Aries, Cancer, and Libra, alike in every thing to that firſt
ſcribed about the centre Capricorn. Now we will conſider the
firſt figure of the Earth, in which, in regard the Axis A B is
clined from perpendicularity upon the diameter Capricorn
cer 23 degrees and an half towards the Sun O, and the arch A I
being alſo 23 degrees and an half, the illumination of the Sun
will illuſtrate the Hemiſphere of the Terreſtrial Globe expoſed
towards the Sun (of which, in this place, half is to be ſeen)
vided from the obſcure part by the Terminator of the light
I M, by which the parallel C D, as being a grand circle, ſhall
come to be divided into equal parts, but all the reſt into parts
equal; being that the terminator of the light I M paſſeth not
by their Poles A B, and the parallel I K, together with all the reſt
1deſcribed within the ſame, and neerer to the pole A, ſhall wholly
be included in the illuminated part; as on the contrary, the
poſite ones towards the Pole B, contained within the
lel L M, ſhall remain in the dark. Moreover, the arch A I
ing equal to the arch F D, and the arch A F, common to them
both, the two arches I K F and A F D ſhall be equal, and each
a quadrant or 90 degrees. And becauſe the whole arch I F M
is a ſemicircle, the arch F M ſhall be a quadrant, and equal to
the other F K I; and therefore the Sun O ſhall be in this ſtate
of the Earth vertical to one that ſtands in the point F. But by
the revolution diurnal about the ſtanding Axis A B, all the points
of the parallel E F paſſe by the ſame point F: and therefore in
that ſame day the Sun, at noon, ſhall be vertical to all the
bitants of the Parallel E F, and will ſeem to them to deſcribe in its
apparent motion the circle which we call the Tropick of Cancer.
But to the inhabitants of all the Parallels that are above the
rallel E F, towards the North pole A, the Sun declineth from
their Vertex or Zenith towards the South; and on the contrary,
to all the inhabitants of the Parallels that are beneath E F,
wards the Equinoctial C D, and the South Pole B, the Meridian
Sun is elevated beyond their Vertex towards the North Pole A.
Next, it is viſible that of all the Parallels, only the greateſt C D
is cut in equal parts by the Terminator of the light I M. But
the reſt, that are beneath and above the ſaid grand circle, are all
interſected in parts unequal: and of the ſuperiour ones, the
midiurnal arches, namely thoſe of the part of the Terreſtrial
face, illuſtrated by the Sun, are bigger than the ſeminocturnal
ones that remain in the dark: and the contrary befalls in the
remainder, that are under the great one C D, towards the pole B,
of which the ſemidiurnal arches are leſſer than the ſeminocturnal,
It is likewiſe apparently manifeſt, that the differences of the ſaid
arches go augmenting, according as the Parallels are neerer to
the Poles, till ſuch time as the parallel I K comes to be wholly in
the part illuminated, and the inhabitants thereof have a day of
twenty four hours long, without any night; and on the contrary,
the Parallel L M, remaining all in obſcurity, hath a night of
twenty four hours, without any day. Come we next to the
third Figure of the Earth, placed with its centre in the point
Cancer, where the Sun ſeemeth to be in the firſt point of
pricorn. We have already ſeen very manifeſtly, that by reaſon
the Axis A B doth not change inclination, but continueth
lel to it ſelf, the aſpect and ſituation of the Earth is the ſame to
an hair with that in the firſt Figure; ſave onely that that
ſphere which in the firſt was illuminated by the Sun, in this
maineth obtenebrated, and that cometh to be luminous, which in
1the firſt was tenebrous: whereupon that which happened before
concerning the differences of dayes and nights, touching the
dayes being greater or leſſer than the nights, now falls out quite
contrary. And firſt, we ſee, that whereas in the firſt Figure the
circle I K was wholly in the light, it is now wholly in the dark;
and the oppoſite arch L M is now wholly in the light, which
was before wholly in the dark. Of the parallels between the
grand circle C D, and the Pole A, the ſemidiurnal arches are now
leſſer than the ſeminocturnal, which before were the contrary.
Of the others likewiſe towards the Pole B, the ſemidiurnal
es are now bigger than the ſeminocturnal, the contrary to what
happened in the other poſition of the Earth. We now ſee the
Sun made vertical to the inhabitants of the Tropick G N, and to
be depreſſed towards the South, with thoſe of the Parallel E F,
by all the arch E C G, that is, 47 degrees; and in ſumme, to have
paſſed from one to the other Tropick, traverſing the Equinoctial,
elevating and declining in the Meridians the ſaid ſpace of 47
grees. And all this mutation is derived not from the inclination
or elevation of the Earth, but on the contrary, from its not
clining or elevating at all; and in a word, by continuing always
in the ſame poſition, in reſpect of the Univerſe, onely with
ing about the Sun ſituate iu the midſt of the ſaid plane, in which
it moveth it ſelf about circularly with its annual motion. And

here is to be noted an admirable accident, which is, that like as
the Axis of the Earth conſerving the ſame direction towards the
Univerſe, or we may ſay, towards the higheſt Sphere of the fixed
ſtars, cauſeth the Sun to appear to elevate and incline ſo great a
ſpace, namely, for 47 degrees, and the fixed Stars to incline or
levate nothing at all; ſo, on the contrary, if the ſame Axis of
the Earth ſhould maintain it ſelf continually in the ſame
tion towards the Sun, or, if you will, towards the Axis of the
Zodiack, no mutation would appear to be made in the Sun about
its elevating or declining, whereupon the inhabitants of one and
the ſame place would alwayes have one and the ſame difference
of dayes and nights, and one and the ſame conſtitution of
ſons, that is, ſome alwayes Winter, others alwayes Summer,
others Spring, &c. but, on the contrary, the alterations in the
fixed Stars would appear very great, as touching their elevation,
and inclination to us, which would amount to the ſame 47
grees. For the underſtanding of which let us return to conſider
the poſition of the Earth, in its firſt Figure, where we ſee the
Axis A B, with the ſuperiour Pole A, to incline towards the Sun;
but in its third Figure, the ſame Axis having kept the ſame
ction towards the higheſt Sphere, by keeping parallel to it ſelf,
inclines no longer towards the Sun with its ſuperiour Pole A, but
1on the contrary reclines from its former poſition gr. 47. and
clineth towards the oppoſite part, ſo that to reſtore the ſame
clination of the ſaid Pole A towards the Sun, it would be
ſite by turning round the Terreſtrial Globe, according to the
circumference A C B D, to tranſport it towards E thoſe ſame
gr. 47. and for ſo many degrees, any whatſoever fixed ſtar
ſerved in the Meridian, would appear to be elevated, or inclined.
Let us come now to the explanation of that which remains, and
let us conſider the Earth placed in the fourth Figure, that is,
with its centre in the firſt point of Libra; upon which the Sun
will appear in the beginning of Aries. And becauſe the Axis of
21[Figure 21]
the Earth, which in the firſt Figure is ſuppoſed to be inclined
on the diameter Capricorn Cancer, and therefore to be in that
ſame plane, which cutting the plane of the grand Orb,
ding to the line Capricorn Cancer, was erected perpendicularly
upon the ſame, tranſpoſed into the fourth Figure, and
ned, as hath alwayes been ſaid, parallel to it ſelf, it ſhall come
to be in a plane in like manner erected to the ſuperficies of
the Grand Orbe, and parallel to the plane, which at right
angles cuts the ſame ſuperficies, according to the diameter
pricorn Cancer. And therefore the line which goeth from
the centre of the Sunne to the centre of the Earth, that is,
O Libra, ſhall be perpendicular to the Axis BA: but the
ſame line which goeth from the centre of the Sunne to the
centre of the Earth, is alſo alwayes perpendicular to the
1circle that is the Terminator of the light; therefore this ſame
circle ſhall paſſe by the Poles A B in the fourth figure, and
in its plain the Axis A B ſhall fall, but the greateſt circle paſſing
by the Poles of the Parallels, divideth them all in equal parts;
therefore the arches I K, E F, C D, G N, L M, ſhall be all
ſemicircles, and the illumin'd Hemiſphere ſhall be this which
looketh towards us, and the Sun, and the Terminator of the
light ſhall be one and the ſame circle A C B D, and the Earth
being in this place ſhall make it Equinoctial to all its Inhabitants.
And the ſame happeneth in the ſecond figure, where the Earth
having its illuminated Hemiſphere towards the Sun, ſheweth us
the other that is obſcure, with its nocturnal arches, which in
like manner are all ſemicircles, and conſequently, here alſo it
maketh the Equinoctial. And laſtly in regard that the line
duced from the centre of the Sun to the centre of the Earth, is
perpendicular to the Axis A B, to which the greateſt circle of
the parallels C D, is likewiſe erect, the ſaid line O Libra ſhall
paſſe of neceſſity by the ſame Plain of the parallel C D, cutting
its circumference in the midſt of the diurnal arch C D; and
therefore the Snn ſhall be vertical to any one that ſhall ſtand
where that interſection is made; but all the Inhabitants of that
Parallel ſhall paſſe the ſame, as being carried about by the
Earths diurnal converſion; therefore all theſ upon that day
ſhall have the Meridian Sun in their vertex. And the Sun at the
ſame time to all the Inhabitants of the Earth ſhall ſeem to
ſcribe the Grand Parallel called the Equinoctial. Furthermore,
foraſmuch as the Earth being in both the Solſtitial points of the
Polar circles I K and L M, the one is wholly in the light, and
the other wholly in the dark; but when the Earth is in the
noctial points, the halves of thoſe ſame polar circles are in the
light, the remainder of them being in the dark; it ſhould not
be hard to underſtand, how that the Earth v. gr. from Cancer
(where the parallel I K is wholly in the dark) to Leo, one part of
the parallel towards the point I, beginneth to enter into the light,
and that the Terminator of the light I M beginneth to retreat
wards the Pole AB, interſecting the circle ACBD nolonger in IM,
but in two other points falling between the terms I A and MB, of
the arches IA and M B; whereupon the Inhabitants of the circle
begin to enjoy the light, and the other Inhabitants of the circle
L M to partake of night. And thus you ſee that by two ſimple
motions made in times proportionate to their bigneſſes, and not
contrary to one another, but performed, as all others that
long to moveable mundane bodies, from Weſt to Eaſt aſſigned
to the Terreſtrial Globe, adequate reaſons are rendred of all
thoſe Phænomena or appearances, for the accommodating of
1which to the ſtability of the Earth it is neceſſary (forſaking that
Symetry which is obſerved to be between the velocities and
nitudes of moveables) to aſcribe to a Sphere, vaſt above all
others, an unconceiveable celerity, whilſt the other leſſer
Spheres move extream ſlowly; and which is more, to make that
motion contrary to all their motions; and, yet again to adde to
the improbability, to make that ſuperiour Sphere forcibly to
tranſport all the inferionr ones along with it contrary to their
proper inclination. And here I refer it to your judgment to
termine which of the two is the moſt probable.
The Suns
nual motion, how
it comes to paſſe,
according to
pernicus.
An admirable
accident depending
on the not inclining
of the Earths axis
SAGR. To me, as far as concerneth ſenſe, there appeareth
no ſmall difference betwixt the ſimplicity and facility of
ting effects by the means aſſigned in this new conſtitution, and
the multiplicity, conſufion, and difficulty, that is found in the
ancient and commonly received Hypotheſis. For if the Univerſe
were diſpoſed according to this multiplicity, it would be
ceſſary to renounce many Maximes in Philoſophy commonly

ceived by Philoſophers, as for inſtance, That Nature doth
not multiply things without neceſſity; and, That She makes uſe
of the moſt facile and ſimple means in producing her effects;
and, That She doth nothing in vain, and the like. I do confeſſe
that I never heard any thing more admirable than this, nor can I
believe that Humane Underſtanding ever penetrated a more
ſublime ſpeculation. I know not what Simplicius may think
of it.
Axiomes
monly admitted by
all Philoſophers.
SIMP. Theſe (if I may ſpeak my judgment freely) do ſeem

to me ſome of thoſe Geometrical ſubtilties which Ariſtotle finds
fault with in Plato, when he accuſeth him that by his too
much ſtudying of Geometry he forſook ſolid Philoſophy; and I
have known and heard very great Peripatetick Philoſophers to
diſſwade their Scholars from the Study of the Mathematicks, as
thoſe that render the wit cavilous, and unable to philoſophate
well; an Inſtitute diametrically contrary to that of Plato, who
admitted uone to Philoſophy, unleſſe he was firſt well entered in
Geometry.
Ariſtotle
eth Plato for being
too ſtudious of
ometry.
SALV. I commend the policy of theſe your Peripateticks, in

dehorting their Diſciples from the Study of Geometry, for that
there is no art more commodious for detecting their fallacies; but
ſee how they differ from the Mathematical Philoſophers, who
much more willingly converſe with thoſe that are well verſt in
the commune Peripatetick Philoſophy, than with thoſe that are
deſtitute of that knowledg, who for want thereof cannot
ſtinguiſh between doctrine and doctrine. But paſſing by this, tell
me I beſeech you, what are thoſe extravagancies and thoſe too
affected ſubtilties that make you think this Copernican Syſteme
the leſſe plauſible?
1
Peripatetick
loſophers condemn
the Study of
metry, and why.
SIMP. To tell you true, I do not very well know; perhaps,
becauſe I have not ſo much as learnt the reaſons that are by
my produced, of thoſe effects, I mean of thoſe ſtations,
dations, acceſſions, receſſions of the Planets; lengthenings and
ſhortnings of dayes, changes of ſeaſons, &c. But omitting the
conſequences that depend on the firſt ſuppoſitions, I find in the
ſuppoſitions themſelves no ſmall difficulties; which ſuppoſitions,
if once they be overthrown, they draw along with them the ruine
of the whole fabrick. Now foraſmuch as becauſe the whole
module of Copernicus ſeemeth in my opinion to be built upon
firm foundations, in that it relyeth upon the mobility of the earth,
if this ſhould happen to be diſproved, there would be no need of
farther diſpute. And to diſprove this, the Axiom of Ariſtotle
is in my judgment moſt ſufficient, That of one ſimple body,
one ſole ſimple motion can be natural: but here in this caſe, to

the Earth, a ſimple body, there are aſſigned 3. if not 4. motions,
and all very different from each other. For beſides the light
motion, as a grave body towards its centre, which cannot be
nied it, there is aſſigned to it a circular motion in a great circle
about the Sun in a year, and a vertiginous converſion about its
own centre in twenty four hours. And that in the next place
which is more exorbitant, & which happly for that reaſon you paſs
over in ſilence, there is aſcribed to it another revolution about
its own centre, contrary to the former of twenty four hours,
and which finiſheth its period in a year. In this my
ing apprehendeth a very great
Four ſeveral
motions aſſigned to
the Earth.
The motion of
deſcent belongs not
to the terreſtrial
Globe, but to its
parts.
SALV. As to the motion of deſcent, it hath already been
cluded not to belong to the Terreſtrial Globe which did never
move with any ſuch motion, nor never ſhall do; but is (if there be
ſuch a thing) that propenſion of its parts to reunite themſelves
to their whole. As, in the next place, to the Annual motion,

and the Diurnal, theſe being both made towards one way, are
very compatible, in the ſame manner juſt as if we ſhould let a
Ball trundle downwards upon a declining ſuperficies, it would in
its deſcent along the ſame ſpontaneouſly revolve in it ſelf. As
to the third motion aſſigned it by Copernicus, namely about it
ſelf in a year, onely to keep its Axis inclined and directed
towards the ſame part of the Firmament, I will tell you a thing
worthy of great conſideration: namely ut tantum abeſt (although
it be made contrary to the other annual) it is ſo far from having
any repugnance or difficulty in it, that naturally and without any

moving cauſe, it agreeth to any whatſoever ſuſpended and
ted body, which if it ſhall be carried round in the circumference
of a circle, immediate of it ſelf, it acquireth a converſion about
its own centre, contrary to that which carrieth it about, and of
1ſuch velocity, that they both finiſh one revolution in the ſame
time preciſely. You may ſee this admirable, and to our

poſe accommodate experience, if putting in a Baſon of water a
Ball that will ſwim; and holding the Baſon in your hand, you
turn round upon your toe, for you ſhall immediatly ſee the Ball
begin to revolve in it ſelf with a motion, contrary to that of the
Baſon, and it ſhall finiſh its revolution, when that of the Baſon it
ſhall finiſh. Now what other is the Earth than a penſil Globe
librated in tenuous and yielding aire, which being carried
bout in a year along the circumference of a great circle, muſt

needs acquire, without any other mover, a revolution about its
own centre, annual, and yet contrary to the other motion in like
manner annual? You ſhall ſee this effect I ſay, but if afterwards
you more narrowly conſider it, you ſhall find this to be no real
thing, but a meer appearance; and that which you think to be
a revolution in it ſelf, you will find to be a not moving at all,
but a continuing altogether immoveable in reſpect of all that
which without you, and without the veſſel is immoveable: for if in
that Ball you ſhall make ſome mark, and conſider to what part of
the Room where you are, or of the Field, or of Heaven it is
ſituate, you ſhall ſee that mark in yours, and the veſſels
tion to look alwayes towards that ſame part; but comparing it to
the veſſel and to your ſelf that are moveable, it will appear to go
altering its direction, and with a motion contrary to yours, and
that of the veſſel, to go ſeeking all the points of its
tion; ſo that with more reaſon you and the baſon may be ſaid
to turn round the immoveable Ball, than that it moveth round
in the baſon. In the ſame manner the Earth ſuſpended and
brated in the circumference of the Grand Orbe, and ſcituate in
ſuch ſort that one of its notes, as for example, its North Pole,
keth towards ſuch a Star or other part of the Firmament, it always
keepeth directed towards the ſame, although carried round by
the annual motion about the circumference of the ſaid Grand
Orbe. This alone is ſufficient to make the Wonder ceaſe, and
to remove all difficulties. But what will Simplicius ſay, if to
this non-indigence of the co-operating cauſe we ſhould adde
an admirable intrinſick vertue of the Terreſtrial Globe, of

ing with its determinate parts towards determinate parts of the
Firmament, I ſpeak of the Magnetick vertue conſtantly
pated by any whatſoever piece of Loade-ſtone. And if every
minute particle of that S one have in it ſuch a vertue, who will

queſtion but that the ſame more powerfully reſides in this whole
Terreſtrial Globe, abounding in that Magnetick matter, and
which happily it ſelf, as to its internal and primary ſubſtance, is
nothing elſe but a huge maſſe of Loade-ſtone.
1
The annual and
diurnal motion are
compatible in the
Earth.
Every penſil and
librated, body
ryed round in the
circumference of a
circle, acquireth of
it ſelf a motion in
it ſelf contrary to
that.
An Experiment
which ſenſibly
ſhews that two
trary motions may
naturally agree
the ſame
able.
The third motion
aſcribed to the
Earth is rather
reſting
able.
An admirable
intern vertœe of the
terreſtrial Globe of
alwayes beholding
the ſame part of
Heaven.
The terreſtriæl
Globe made of
Loade-ſtone.
SIMP. Then you are one of thoſe it ſeems that hold the

netick Phyloſophy William ^{*} Gilbert.
An eminent
Doctor of Phyſick,
our Countreyman,
born at Coloheſter,
and famous for this
his learned
tiſe, publiſhed
bout 60 years ſince
at London, The
Magnetick
loſophy of William
Gilbert.
SALV. I am for certain, and think that all thoſe that have
ſeriouſly read his Book, and tried his experiments, will bear me
company therein; nor ſhould I deſpair, that what hath befallen
me in this caſe, might poſſibly happen to you alſo, if ſo be a
rioſity, like to mine, and a notice that infinite things in Nature
are ſtill conceal'd from the wits of mankind, by delivering you
from being captivated by this or that particular writer in natural
things, ſhould but ſlacken the reines of your Reaſon, and
lifie the contumacy and tenaceouſneſſe of your ſenſe; ſo as that
they would not refuſe to hearken ſometimes to novelties never

before ſpoken of. But (permit me to uſe this phraſe) the
nimity of vulgar Wits is come to that paſſe, that not only like
blind men, they make a gift, nay tribute of their own aſſent to
whatſoever they find written by thoſe Authours, which in the
infancy of their Studies were laid before them, as authentick by
their Tutors, but refuſe to hear (not to ſay examine) any new
Propoſition or Probleme, although it not only never hath been
confuted, but not ſo much as examined or conſidered by their
Authours. Amongſt which, one is this, of inveſtigating what is
the true, proper, primary, interne, and general matter and
ſtance of this our Terreſtrial Globe; For although it never came
into the mind either of Ariſtotle, or of any one elſe, before
liam Gilbert to think that it might be a Magnet, ſo far are
ſtotle and the reſt from confuting this opinion, yet nevertheleſſe
I have met with many, that at the very firſt mention of it, as a
Horſe at his own ſhadow, have ſtart back, and refuſed to
courſe thereof, and cenſured the conceipt for a vain Chymæra,
yea, for a ſolemn madneſſe: and its poſſible the Book of Gilbert
had never come to my hands, if a Peripatetick Philoſopher, of great
fame, as I believe, to free his Library from its contagion, had not
given it me.
The
mity of Popular
Wits.
SIMP. I, who ingenuouſly confeſſe my ſelf to be one of
thoſe vulgar Wits, and never till within theſe few dayes that I
have been admitted to a ſhare in your conferences, could I
tend to have in the leaſt withdrawn from thoſe trite and
lar paths, yet, for all that, I think I have advantaged my ſelf ſo
much, as that I could without much trouble or difficulty, maſter
the roughneſſes of theſe novel and fantaſtical opinions.
SALV. If that which Gilbert writeth be true, then is it no
pinion, but the ſubject of Science; nor is it new, but as antient
as the Earth it ſelf; nor can it (being true) be rugged or
cult, but plain and eaſie; and when you pleaſe I ſhall make you
feel the ſame in your hand, for that you of your ſelf fancy it to
1be a Ghoſt, and ſtand in fear of that which hath nothing in it of
dreadfull, like as a little child doth fear the Hobgoblin, without
knowing any more of it, ſave the name; as that which beſides
the name is nothing.
SIMP. I ſhould be glad to be informed, and reclaimed from
an errour.
SALV. Anſwer me then to the queſtions that I ſhall ask you.
And firſt of all, Tell me whether you believe, that this our Globe,
which we inhabit and call Earth, conſiſteth of one ſole and
ple matter, or elſe that it is an aggregate of matters different
from each other.
SIMP. I ſee it to be compoſed of ſubſtances and bodies very

different; and firſt, for the greateſt parts of the compoſition,
I ſee the Water and the Earth, which extreamly differ from one
another.
The Terreſtrial
Globe compoſed of
ſundry matters.
SAIV. Let us, for this once, lay aſide the Seas and other
ters, and let us conſider the ſolid parts, and tell me, if you think
them one and the ſame thing, or elſe different.
SIMP. As to appearance, I ſee that they are different things,
there being very great heaps of unfruitful ſands, and others of
fruitful ſoiles; There are infinite ſharp and ſteril mountains, full
of hard ſtones and quarries of ſeveral kinds, as Porphyre,
blaſter, Jaſper, and a thouſand other kinds of Marbles: There
are vaſt Minerals of ſo many kinds of metals; and in a word,
ſuch varieties of matters, that a whole day would not ſuffice
ly to enumerate them.
SALV. Now of all theſe different matters, do you think,
that in the compoſition of this grand maſſe, there do concur
tions, or elſe that amongſt them all there is one part that far
ceeds the reſt, and is as it were the matter and ſubſtance of the
immenſe lump?
SIMP. I believe that the Stones, Marbles, Metals, Gems, and
the ſo many other ſeveral matters are as it were Jewels, and
teriour and ſuperficial Ornaments of the primary Globe, which
in groſſe, as I believe, doth without compare exceed all theſe
things put together.
SALV. And this principal and vaſt maſſe, of which thoſe
things above named are as it were excreſſences and ornaments, of
what matter do you think that it is compoſed?
SIMP. I think that it is the ſimple, or leſſe impure element of
Earth.
SALV. But what do you underſtand by Earth? Is it haply
that which is diſperſed all over the fields, which is broke up with
Mattocks and Ploughs, wherein we ſowe corne, and plant fruits,
and in which great boſcages grow up, without the help of
1ture, and which is, in a word, the habitation of all animals, and
the womb of all vegetables?
SIMP. Tis this that I would affirm to be the ſubſtance of this
our Globe.
SALV. But in this you do, in my judgment, affirm that which
is not right: for this Earth which is broke up, is ſowed, and is
fertile, is but one part, and that very ſmall of the ſurface of the
Globe, which doth not go very deep, yea, its depth is very ſmall,
in compariſon of the diſtance to the centre: and experience
ſheweth us, that one ſhall not dig very low, but one ſhall finde
matters very different from this exteriour ſcurf, more ſolid, and
not good for the production of vegetables. Beſides the interne
parts, as being compreſſed by very huge weights that lie upon
them, are, in all probability, ſlived, and made as hard as any
hard rock. One may adde to this, that fecundity would be in
vain conferred upon thoſe matters which never were deſigned to
bear fruit, but to reſt eternally buried in the profound and dark
abyſſes of the Earth.
SIMP. But who ſhall aſſure us, that the parts more inward
and near to the centre are unfruitful? They alſo may, perhaps,
have their productions of things unknown to us?
SALV. You may aſwell be aſſured thereof, as any man elſe,
as being very capable to comprehend, that if the integral bodies
of the Univerſe be produced onely for the benefit of Mankind,
this above all the reſt ought to be deſtin d to the ſole
ces of us its inhabitants. But what beneſit can we draw from
matters ſo hid and remote from us, as that we ſhall never be

ble to make uſe of them? Therefore the interne ſubſtance of
this our Globe cannot be a matter frangible, diſſipable, and
coherent, like this ſuperficial part which we call ^{*} EARTH: but

it muſt, of neceſſity, be a moſt denſe and ſolid body, and in a
word, a moſt hard ſtone. And, if it ought to be ſo, what reaſon
is there that ſhould make you more ſcrupulous to believe that it
is a Loadſtone than a Porphiry, a Jaſper, or other hard
ble? Happily if Gilbert had written, that this Globe is all

pounded within of ^{*} Pietra Serena, or of Chalcedon, the paradox
would have ſeemed to you leſſe exorbitant?
The interne parts
of the terreſtrial
Globe muſt of
ceſſity be ſolid.
* Or MOULD.
Of which with
the Latin
tour, I muſt once
more profeſſe my
ſelf ignorant.
SIMP. That the parts of this Globe more intern are more
compreſſed, and ſo more ſlived together and ſolid, and more
and more ſo, according as they lie lower, I do grant, and ſo
likewiſe doth Ariſtotle, but that they degenerate and become
other than Earth, of the ſame ſort with this of the ſuperficial
parts, I ſee nothing that obliege h me to believe.
SALV. I undertook not this diſcourſe with an intent to prove
demonſtratively that the primary and real ſubſtance of this our
1Globe is Load-ſtone; but onely to ſhew that no reaſon could be
given why one ſhould be more unwilling to grant that it is of
Load-ſtone, than of ſome other matter. And if you will but

ſeriouſly conſider, you ſhall find that it is not improbable, that
one ſole, pure, and arbitrary name, hath moved men to think
that it conſiſts of Earth; and that is their having made uſe
monly from the beginning of this word Earth, as well to
ſie that matter which is plowed and ſowed, as to name this our
Globe. The denomination of which if it had been taken from
ſtone, as that it might as well have been taken from that as
from the Earth; the ſaying that its primary ſubſtance was ſtone,
would doubtleſſe have found no ſcruple or oppoſition in any
man. And is ſo much the more probable, in that I verily
lieve, that if one could but pare off the ſcurf of this great Globe,
taking away but one full thouſand or two thouſand yards; and
afterwards ſeperate the Stones from the Earth, the
on of the ſtones would be very much biger than that of the
tile Mould. But as for the reaſons which concludently prove de
facto, that is our Globe is a Magnet, I have mentioned none of
them, nor is this a time to alledg them, and the rather, for that
to your benefit you may read them in Gilbert; onely to
rage you to the peruſal of them, I will ſet before you, in a

litude of my own, the method that he obſerved in his
phy. I know you underſtand very well how much the
ledg of the accidents is ſubſervient to the inveſtigation of the
ſubſtance and eſſence of things; therefore I deſire that you
would take pains to informe your ſelf well of many accidents and
properties that are found in the Magnet, and in no other ſtone,

or body; as for inſtance of attracting Iron, of conferring
on it by its ſole preſence the ſame virtue, of communicating
likewiſe to it the property of looking towards the Poles, as it
alſo doth it ſelf; and moreover endeavour to know by trial,
that it containeth in it a virtue of conferring upon the magnetick
needle not onely the direction under a Meridian towards the
Poles, with an Horizontal motion, (a property a long time ago
known) but a new found accident, of declining (being ballanced
under the Meridian before marked upon a little ſpherical
net) of declining I ſay to determinate marks more or leſſe,
cording as that needle is held nearer or farther from the Pole,
till that upon the Pole it ſelf it erecteth perpendicularly,
as in the middle parts it is parallel to the Axis. Furthermore
cure a proof to be made, whether the virtue of attracting Iron,
reſiding much more vigorouſly about the Poles, than about the
middle parts, this force be not notably more vigorous in one
Pole than in the other, and that in all pieces of Magnet; the
1ſtronger of which Poles is that which looketh towards the South.
Obſerve, in the next place, that in a little Magnet this South and
more vigorous Pole, becometh weaker, when ever it is to take
up an iron in preſence of the North Pole, of another much
ger Magnet: and not to make any tedious diſcourſe of it,
tain your ſelf, by experience, of theſe and many other properties
deſcribed by Gilbert, which are all ſo peculiar to the Magnet, as

that none of them agree with any other matter. Tell me now,
Simplicius, if there were laid before you a thouſand pieces of
ſeveral matters, but all covered and concealed in a cloth, under
which it is hid, and you were required, without uncovering them,
to make a gueſſe, by external ſignes, at the matter of each of
them, and that in making trial, you ſhould hit upon one that
ſhould openly ſhew it ſelf to have all the properties by you
dy acknowledged to reſide onely in the Magnet, and in no other
matter, what judgment would you make of the eſſence of ſuch a
body? Would you ſay, that it might be a piece of Ebony, or
Alablaſter, or Tin.
Our Globe would
have been called
ſtone, in ſtead of
Earth, if that
name had been
uen it in the
ginning.
The method of
Gilbert in his
loſophy.
Many
ties in the
net.
An Argument
proving the
ſtrial Globe to be
a Magnet.
SIMP. I would ſay, without the leaſt hæſitation, that it was a
piece of Load-ſtone.
SALV. If it be ſo, ſay reſolutely, that under this cover and
ſcurf of Earth, ſtones, metals, water, &c. there is hid a great
Magnet, foraſmuch as about the ſame there may be ſeen by any
one that will heedfully obſerve the ſame, all thoſe very accidents
that agree with a true and viſible Globe of Magnet; but if no
more were to be ſeen than that of the Declinatory Needle, which
being carried about the Earth, more and more inclineth, as it
proacheth to the North Pole, and declineth leſſe towards the
quinoctial, under which it finally is brought to an Æquilibrium,
it might ſerve to perſwade even the moſt ſcrupulous judgment. I
forbear to mention that other admirable effect, which is ſenſibly
obſerved in every piece of Magnet, of which, to us inhabitants
of the Northern Hemiſphere, the Meridional Pole of the ſaid
net is more vigorous than the other; and the difference is found
greater, by how much one recedeth from the Equinoctial; and
under the Equinoctial both the parts are of equal ſtrength, but
notably weaker. But, in the Meridional Regions, far diſtant
from the Equinoctial, it changeth nature, and that part which to
us was more weak, acquireth more ſtrength than the other: and
all this I confer with that which we ſee to be done by a ſmall
piece of Magnet, in the preſence of a great one, the vertue of
which ſuperating the leſſer, maketh it to become obedient to it,
and according as it is held, either on this or on that ſide the
noctial of the great one, maketh the ſelf ſame mutations,
which I have ſaid are made by every Magnet, carried on this
1ſide, or that ſide of the Equinoctiall of the Earth.
SAGR. I was perſwaded, at the very firſt reading of the Book
of Gilbertus; and having met with a moſt excellent piece of

Magnet, I, for a long time, made many Obſervations, and all
worthy of extream wonder; but above all, that ſeemeth to me
very ſtupendious of increaſing the faculty of taking up Iron ſo
much by arming it, like as the ſaid Authour teacheth; and with
arming that piece of mine, I multiplied its force in octuple
tion; and whereas unarmed it ſcarce took up nine ounces of
Iron, it being armed did take up above ſix pounds: And, it
may be, you have ſeen this Loadſtone in the ^{*} Gallery of your

Moſt Serene Grand Duke (to whom I preſented it) upholding
two little Anchors of Iron.
|The Magnet
armed takes up
much more Iron,
than when
med.
+ Or Cloſet of
rarities.
SALV. I ſaw it many times, and with great admiration, till
that a little piece of the like ſtone gave me greater cauſe of
der, that is in the keeping of our Academick, which being no
more than of ſix ounces weight, and ſuſtaining, when unarmed,
hardly two ounces, doth, when armed, take up 160. ounces, ſo
as that it is of 80. times more force armed than unarmed, and
takes up a weight 26. times greater than its own; a much greater
wonder than Gilbert could ever meet with, who writeth, that he
could never get any Loadſtone that could reach to take up four
times its own weight.
SAGR. In my opinion, this Stone offers to the wit of man a
large Field to Phyloſophate in; and I have many times thought
with my ſelf, how it can be that it conferreth on that Iron, which
armeth it, a ſtrength ſo ſuperiour to its own; and finally, I finde
nothing that giveth me ſatisfaction herein; nor do I find any
thing extraordinary in that which Gilbert writes about this
cular; I know not whether the ſame may have befallen
you.
SALV. I extreamly praiſe, admire, and envy this Authour,
for that a conceit ſo ſtupendious ſhould come into his minde,
touching a thing handled by infinite ſublime wits, and hit upon
by none of them: I think him moreover worthy of
nary applauſe for the many new and true Obſervations that he
made, to the diſgrace of ſo many fabulous Authours, that write
not only what they do not know, but what ever they hear
ken by the fooliſh vulgar, never ſeeking to aſſure themſelves of
the ſame by experience, perhaps, becauſe they are unwilling to
diminiſh the bulk of their Books. That which I could have
ſired in Gilbert, is, that he had been a little greater
an, and particularly well grounded in Geometry, the practice
whereof would have rendered him leſs reſolute in accepting thoſe
reaſons for true Demonſtrations, which he produceth for true
1cauſes of the true concluſions obſerved by himſelf. Which
ſons (freely ſpeaking) do not knit and bind ſo faſt, as thoſe
doubtedly ought to do, in that of natural, neceſſary, and laſting
concluſions may be alledged. And I doubt not, but that in
ceſſe of time this new Science will be perfected with new
vations, and, which is more, with true and neceſſary

tions. Nor ought the glory of the firſt Inventor to be thereby
diminiſhed, nor do I leſſe eſteem, but rather more admire, the
Inventor of the Harp (although it may be ſuppoſed that the
ſtrument at firſt was but rudely framed, and more rudely
ed) than an hundred other Artiſts, that in the inſuing Ages
ced that profeſſion to great perfection. And methinks, that
tiquity had very good reaſon to enumerate the firſt Inventors of
the Noble Arts amongſt the Gods; ſeeing that the common wits
have ſo little curioſity, and are ſo little regardful of rare and
gant things, that though they ſee and hear them exercirated by
the exquifite profeſſors of them, yet are they not thereby
ſwaded to a deſire of learning them. Now judge, whether
cities of this kind would ever have attempted to have found out
the making of the Harp, or the invention of Muſick, upon the
hint of the whiſtling noiſe of the dry ſinews of a Tortois, or
from the ſtriking of four Hammers. The application to great
inventions moved by ſmall hints, and the thinking that under a
primary and childiſh appearance admirable Arts may lie hid, is
not the part of a trivial, but of a ſuper-humane ſpirit. Now
ſwering to your demands, I ſay, that I alſo have long thought
upon what might poſſibly be the cauſe of this ſo tenacious and
potent union, that we ſee to be made between the one Iron that
armeth the Magnet, and the other that conjoyns it ſelf unto it.

And firſt, we are certain, that the vertue and ſtrength of the ſtone
doth not augment by being armed, for it neither attracts at
greater diſtance, nor doth it hold an Iron the faſter, if between it,
and the arming or cap, a very fine paper, or a leaf of beaten gold,
be interpoſed; nay, with that interpoſition, the naked ſtone
takes up more Iron than the armed. There is therefore no
ration in the vertue, and yet there is an innovation in the effect.

And becauſe its neceſſary, that a new effect have a new cauſe, if
it be inquired what novelty is introduced in the act of taking up
with the cap or arming, there is no mutation to be diſcovered, but
in the different contact; for whereas before Iron toucht
ſtone, now Iron toucheth Iron. Therefore it is neceſſary to
clude, that the diverſity of contacts is the cauſe of the diverſity

of effects. And for the difference of contacts it cannot, as I ſee,
be derived from any thing elſe, ſave from that the ſubſtance of
the Iron is of parts more ſubtil, more pure, and more
1ed than thoſe of the Magnet, which are more groſſe, impure, and
rare. From whence it followeth, that the ſuperficies of two
rons that are to touch, by being exquiſitely plained, filed, and
burniſhed, do ſo exactly conjoyn, that all the infinite points of
the one meet with the infinite points of the other; ſo that the
filaments, if I may ſo ſay, that collegate the two Irons, are many
more than thoſe that collegate the Magnet to the Iron, by reaſon
that the ſubſtance of the Magnet is more porous, and leſſe
pact, which maketh that all the points and filaments of the
ſtone do not cloſe with that which it unites unto. In the next
place, that the ſubſtance of Iron (eſpecially the well refined, as
namely, the pureſt ſteel) is of parts much more denſe, ſubtil,
and pure than the matter of the Loadſtone, is ſeen, in that one
may bring its edge to an extraordinary ſharpneſſe, ſuch as is that
of the Raſor, which can never be in any great meaſure effected in
a piece of Magnet. Then, as for the impurity of the Magnet, and

its being mixed with other qualities of ſtone, it is firſt ſenſibly
diſcovered by the colour of ſome little ſpots, for the moſt part
white; and next by preſenting a needle to it, hanging in a
thread, which upon thoſe ſtonyneſſes cannot find repoſe, but
being attracted by the parts circumfuſed, ſeemeth to fly from

^{*} thoſe, and to leap upon the Magnet contiguous to them: and
as ſome of thoſe Heterogeneal parts are for their magnitude
ry viſible, ſo we may believe, that there are others, in great
bundance, which, for their ſmallneſſe, are imperceptible, that are
diſſeminated throughout the whole maſſe. That which I ſay,
(namely, that the multitude of contacts that are made between
Iron and Iron, is the cauſe of the ſo ſolid conjunction) is
firmed by an experiment, which is this, that if we preſent the
ſharpned point of a needle to the cap of a Magnet, it will ſtick
no faſter to it, than to the ſame ſtone unarmed: which can
proceed from no other cauſe, than from the equality of the
tacts that are both of one ſole point. But what then? Let a
^{*} Needle be taken and placed upon a Magnet, ſo that one of its

extremities hang ſomewhat over, and to that preſent a Nail; to
which the Needle will inſtantly cleave, inſomuch that
ing the Nail, the Needle will ſtand in ſuſpenſe, and with its two
ends touching the Magnet and the Iron; and withdrawing the
Nail yet a little further, the Needle will forſake the Magnet;
provided that the eye of the Needle be towards the Nail, and
the point towards the Magnet; but if the eye be towards the
Loadſtone, in withdrawing the Nail the Needle will cleave to
the Magnet; and this, in my judgment, for no other reaſon,
ſave onely that the Needle, by reaſon it is bigger towards the
eye, toucheth in much more points than its ſharp point doth.
1
The firſt
vers and inventers
of things ought to
be admired.
The true cauſe
of the
tion of vertue in
the Magnet, by
means of the
ming.
Of a new effect
its neceſſary that
the cauſe be
wiſe new.
It is proved,
that Iron conſists
of parts more
til, pure, and
pact than the
net.
A ſenſible proof
of the impurity of
the Magnet.
* The
hereby
that the
doth not all
ſiſt of magnetick
matter, but that
the whiter ſpecks
being weak, thoſe
other parts of the
Loadſtone of a
more dark &
ſtant colour,
tain all that vertue
wherewith bodies
are attracted.
* A common
ſewing needle.
SAGR. Your whole diſcourſe hath been in my judgment very
concluding, and this experiment of the Needle hath made me
think it little inferiour to a Mathematical Demonſtration; and
I ingenuouſly confeſſe, that in all the Magnetick Philoſophy, I
never heard or read any thing, that with ſuch ſtrong reaſons
gave account of its ſo many admirable accidents, of which, if the
cauſes were with the ſame perſpicuity laid open, I know not
what ſweeter food our Intellects could deſire.
SALV. In ſeeking the reaſons of concluſions unknown unto
us, it is requiſite to have the good fortune to direct the
courſe from the very beginning towards the way of truth; in
which if any one walk, it will eaſily happen, that one ſhall meet
with ſeveral other Propoſitions known to be true, either by
putes or experiments, from the certainty of which the truth of
ours acquireth ſtrength and evidence; as it did in every reſpect
happen to me in the preſent Probleme, for being deſirous to
ſure my ſelf, by ſome other accident, whether the reaſon of the
Propoſition, by me found, were true; namely, whether the
ſtance of the Magnet were really much leſſe continuate than that
of Iron or of Steel, I made the Artiſts that work in the Gallery
of my Lord the Grand Duke, to ſmooth one ſide of that piece
of Magnet, which formerly was yours, and then to poliſh and
burniſh it; upon which to my ſatisfaction I found what I deſired.
For I diſcovered many ſpecks of colour different from the reſt,
but as ſplendid and bright, as any of the harder ſort of ſtones;
the reſt of the Magnet was polite, but to the tact onely, not
being in the leaſt ſplendid; but rather as if it were ſmeered over
with ſoot; and this was the ſubſtance of the Load ſtone, and
the ſhining part was the fragments of other ſtones intermixt
therewith, as was ſenſibly made known by preſenting the face
thereof to filings of Iron, the which in great number leapt to
the Load-ſtone, but not ſo much as one grain did ſtick to the
ſaid ſpots, which were many, ſome as big as the fourth part of
the nail of a mans finger, others ſomewhat leſſer, the leaſt of
all very many, and thoſe that were ſcarce viſible almoſt
merable. So that I did aſſure my ſelf, that my conjecture was
true, when I firſt thought that the ſubſtance of the Magnet
was not cloſe and compact, but porous, or to ſay better,
gy; but with this difference, that whereas the ſponge in its
cavities and little cels conteineth Air or Water, the Magnet hath
its pores full of hard and heavy ſtone, as appears by the
ſite luſtre which thoſe ſpecks receive. Whereupon, as I have ſaid
from the beginning, applying the ſurface of the Iron to the
perficies of the Magnet the minute particles of the Iron, though
perhaps more continuate than theſe of any other body (as its
1ſhining more than any other matter doth ſhew) do not all, nay
but very few of them incounter pure Magnet; and the contacts
being few, the union is but weak. But becauſe the cap of the
Load-ſtone, beſides the contact of a great part of its ſuperficies,
inveſts its ſelf alſo with the virtue of the parts adjoyning,
though they touch not; that ſide of it being exactly ſmoothed
to which the other face, in like manner well poliſht of the Iron to
be attracted, is applyed, the contact is made by
ble minute particles, if not haply by the infinite points of both
the ſuperficies, whereupon the union becometh very ſtrong.
This obſervation of ſmoothing the ſurfaces of the Irons that are
to touch, came not into the thoughts of Gilbert, for he makes
the Irons convex, ſo that their contact is very ſmall; and
upon it cometh to paſſe that the tenacity, wherewith thoſe Irons
conjoyn, is much leſſer.
SAGR. I am, as I told you before, little leſſe ſatisfied with
this reaſon, that if it were a pure Geometrical Demonſtration;
and becauſe we ſpeak of a Phyſical Problem, I believe that alſo
Simplicius will find himſelf ſatisfied as far as natural ſcience
mits, in which he knows that Geometrical evidence is not to be
required.
SIMP. I think indeed, that Salviatus with a fine

cution hath ſo manifeſtly diſplayed the cauſe of this effect, that
any indifferent wit, though not verſt in the Sciences, may
prehend the ſame; but we, confining our ſelves to the terms of
Art, reduce the cauſe of theſe and other the like natural effects
to Sympathy, which is a certain agreement and mutual appetite
which ariſeth between things that are ſemblable to one another
in qualities; as likewiſe on the contrary that hatred & enmity for
which other things ſhun & abhor one another we call Antipathy.
Sympathy and
Antipathy, terms
uſed by
phers to give a
ſon eaſily of
ny narural effests.
SAGR. And thus with theſe two words men come to render
reaſons of a great number of accidents and effects which we ſee
not without admiration to be produced in nature. But this kind
of philoſophating ſeems to me to have great ſympathy with a

certain way of Painting that a Friend of mine uſed, who writ
upon the Tele or Canvaſſe in chalk, here I will have the
tain with Diana and her Nimphs, there certain Hariers, in this
corner I will have a Huntſ-man with the Head of a Stag, the reſt
ſhall be Lanes, Woods, and Hills; and left the remainder for
the Painter to ſet forth with Colours; and thus he perſwaded
himſelf that he had painted the Story of Acteon, when as he had
contributed thereto nothing of his own more than the names.
But whether are we wandred with ſo long a digreſſion, contrary
to our former reſolutions? I have almoſt forgot what the point
was that we were upon when we fell into this magnetick
1courſe; and yet I had ſomething in my mind that I intended to
have ſpoken upon that ſubject.
A pleaſant
ampleaeclaring the
invalidity of ſome
Phyloſophical
gumentations.
SALV. We were about to demonſtrate that third motion
ſcribed by Copernicus to the Earth to be no motion but a
ſcence and maintaining of it ſelf immutably directed with its
terminate parts towards the ſame & determinate parts of the
verſe, that is a perpetual conſervation of the Axis of its diurnal
revolution parallel to it ſelf, and looking towards ſuch and ſuch
fixed ſtars; which moſt conſtant poſition we ſaid did naturally
agree with every librated body ſuſpended in a fluid and yielding
medium, which although carried about, yet did it not change
rectionin reſpect of things external, but onely ſeemed to revolve in
its ſelf, in reſpect of that which carryed it round, and to the
veſſel in which it was tranſported. And then we added to this
ſimple and natural accident the magnetick virtue, whereby the
ſelf Terreſtrial Globe might ſo much the more conſtantly keep it
immutable, -----
SAGR. Now I remember the whole buſineſſe; and that which
then came into my minde, & which I would have intimated, was a
certain conſideration touching the ſcruple and objection of
plicius, which he propounded againſt the mobility of the Earth,

taken from the multiplicity of motions, impoſſible to be aſſigned
to a ſimple body, of which but one ſole and ſimple motion,
cording to the doctrine of Ariſtotle, can be natural; and that
which I would have propoſed to conſideration, was the Magnet,
to which we manifeſtly ſee three motions naturally to agree:
one towards the centre of the Earth, as a Grave; the ſecond is
the circular Horizontal Motion, whereby it reſtores and
ſerves its Axis towards determinate parts of the Univerſe; and
the third is this, newly diſcovered by Gilbert, of inclining its
Axis, being in the plane of a Meridian towards the ſurface of the
Earth, and this more and leſſe, according as it ſhall be diſtant
from the Equinoctial, under which it is parallel to the Axis of
the Earth. Beſides theſe three, it is not perhaps improbable,
but that it may have a fourth, of revolving upon its own Axis, in
caſe it were librated and ſuſpended in the air or other fluid and
yielding Medium, ſo that all external and accidental impediments
were removed, and this opinion Gilbert himſelf ſeemeth alſo to
applaud. So that, Simplicius, you ſee how tottering the Axiome
of Ariſtotle is.
The ſeveral
tural motions of
the Magnet.
SIMP. This doth uot only not make againſt the Maxime, but
not ſo much as look towards it: for that he ſpeaketh of a fimple
body, and of that which may naturally conſiſt therewith; but
you propoſe that which befalleth a mixt body; nor do you tell
us of any thing that is new to the doctrine of Ariſtotle, for that
1he likewiſe granteth to mixt bodies compound motions by -----
SAGR. Stay a little, Simplicius, & anſwer me to the queſtions
I ſhall ask you. You ſay that the Load-ſtone is no ſimple body,

now I defire you to tell me what thoſe ſimple bodies are, that
mingle in compoſing the Load-ſtone.
Ariſtole grants
a compound motion
to mixt bodies.
SIMP. I know not how to tell you th'ingredients nor ſimples
preciſely, but it ſufficeth that they are things elementary.
SALV. So much ſufficeth me alſo. And of theſe ſimple
mentary bodies, what are the natural motions?
SIMP. They are the two right and ſimple motions, ſurſum
and deorſum.
SAGR. Tell me in the next place? Do you believe that the
motion, that ſhall remain natural to that ſame mixed body, ſhould
be one that may reſult from the compoſition of the two ſimple
natural motions of the ſimple bodies compounding, or that it
may be a motion impoſſible to be compoſed of
The motion of
mixt bodies ought
to be ſuch as may
reſult from the
compoſition of the
motions of the
ple bodies
pounding.
SIMP. I believe that it ſhall move with the motion reſulting
from the compoſition of the motions of the ſimple bodies
pounding, and that with a motion impoſſible to be compoſed of
theſe, it is impoſſible that it ſhould move.
SAGR. But, Simplicius, with two right and ſimple motions, you
ſhall never be able to compoſe a circular motion, ſuch as are the

two, or three circular motions that the magnet hath: you ſee
then into what abſurdities evil grounded Principles, or, to ſay

better, the ill-inferred conſequences of good Principles carry a
man; for you are now forced to ſay, that the Magnet is a
ture compounded of ſubſtances elementary and cœleſtial, if you
will maintain that the ſtraight motion is a peculiar to the
ments, and the circular to the cœleſtial bodies. Therefore if
you will more ſafely argue, you muſt ſay, that of the integral
bodies of the Univerſe, thoſe that are by nature moveable, do all
move circularly, and that therefore the Magnet, as a part of the

true primary, and integral ſubſtance of our Globe, pertaketh of
the ſame qualities with it. And take notice of this your fallacy,
in calling the Magnet a mixt body, and the Terreſtrial Globe a
ſimple body, which is ſenſibly perceived to be a thouſand times
more compound: for, beſides that it containeth an hundred an
hundred matters, exceeding different from one another, it
taineth great abundance of this which you call mixt, I mean
of the Load-ſtone. This ſeems to me juſt as if one ſhould call

bread a mixt body, and ^{*} Pannada a ſimple body, in which there
is put no ſmall quantity of bread, beſides many other things
ble. This ſeemeth to me a very admirable thing, amongſt others
1
of the Peripateticks, who grant (nor can it be denied) that our
Terreſtrial Globe is, de facto, a compound of infinite different
matters; and grant farther that of compound bodies the motion
ought to be compound: now the motions that admit of
ſition are the right and circular: For the two right motions, as
being contrary, are incompatible together, they affirm, that the
pure Element of Earth is no where to be found; they confeſſe,
that it never hath been moved with a local motion; and yet they
will introduce in Nature that body which is not to be found, and
make it move with that motion which it never exerciſed, nor
ver ſhall do, and to that body which hath, and ever had a being,
they deny that motion, which before they granted, ought
rally to agree therewith.
With two right
motions one cannot
compoſe circular
motions.
Philoſophers are
forced to confeſſe
that the Magnet
is compounded of
cœleſtial
ces, and of
tary.
The errour of
thoſe who call the
Magnet a mixt
body, and the
reſtrial Globe
ſimble body.
* Ogliopotrida
a Spaniſh diſh of
many ingredients
boild together.
The Diſcourſes
of Peripateticks,
full of errours and
contradictions.
SALV. I beſeech you, Sagredus, let us not weary our ſelves
any more about theſe particulars, and the rather, becauſe you
know that our purpoſe was not to determine reſolutely, or to
accept for true, this or that opinion, but only to propoſe for our
divertiſement ſuch reaſons, and anſwers as may be alledged on
the one ſide, or on the other; and Simplicius maketh this
ſwer, in defence of his Peripateticks, therefore let us leave the
judgment in ſuſpenſe, and remit the determination into the
hands of ſuch as are more known than we. And becauſe I think
that we have, with ſufficient prolixity, in theſe three dayes,
courſed upon the Syſteme of the Univerſe, it will now be
nable, that we proceed to the grand accident, from whence our
Diſputations took beginning, I mean, of the ebbing and flowing
of the Sea, the cauſe whereof may, in all probability, be referred
to the motion of the Earth. But that, if you ſo pleaſe, we will
reſerve till to morrow. In the mean time, that I may not forget
it, I will ſpeak to one particular, to which I could have wiſhed,
that Gilbert had not lent an ear; I mean that of admitting, that

in caſe a little Sphere of Loadſtone might be exactly librated, it
would revolve in it ſelf; becauſe there is no reaſon why it ſhould
do ſo; For if the whole Terreſtrial Globe hath a natural
ty of revolving about its own centre in twenty four hours, and
that all its parts ought to have the ſame, I mean, that faculty of
turning round together with their whole, about its centre in
ty four hours; they already have the ſame in effect, whilſt that,
being upon the Earth, they turn round along with it: And the
aſſigning them a revolution about their particular centres, would
be to aſcribe unto them a ſecond motion much different from the
firſt; for ſo they would have two, namely, the revolving in
ty four hours about the centre of their whole; and the turning
about their own: now this ſecond is arbitrary, nor is there any
1reaſon for the introducing of it: If by pluoking away a piece
of Loadſtone from the whole natural maſſd, it were deprived of
the faculty of following it, as it did, whilſt it was unitedy thereto,
ſo that it is thereby deprived of the revodution about the
ſal centre of the Terreſtrial Globe, it might Chaply, with
what greater probability be thought by ſome, that the ſaid
net was to appropriate to it ſelf a new converſion about its
cular centre; but if it do no leſſe, when ſeparated, than when
conjoyned, continue always to purſue its firſt, eternal, and
ral courſe, to what purpoſe ſhould we go about to obtrude upon
it another new one?
An
ble effect admired
by Gilbertus in the
Loadſtone.
SAGR. I underſtand you very well, and this puts me in mind
of a Diſcourſe very like to this for the vanity of it, falling from

certain Writers upon the Sphere, and I think, if I well
ber, amongſt others from Sacroboſco, who, to ſhew how the
lement of Water, doth, together with the Earth, make a
pleat Spherical Figure, and ſo between them both compoſe this
our Globe, writeth, that the ſeeing the ſmall ^{*} particles of water
ſhape themſelves into rotundity, as in the drops, and in the dew
daily apparent upon the leaves of ſeveral herbs, is a ſtrong
gument; and becauſe, according to the trite Axiome, there is
the ſame reaſon for the whole, as for the parts, the parts affecting
that ſame figure, it is neceſſary that the ſame is proper to the
whole Element: and truth is, methinks it is a great overſight
that theſe men ſhould not perceive ſo apparent a vanity, and
ſider that if their argument had run right, it would have
ed, that not only the ſmall drops, but that any whatſoever greater
quantity of water ſeparated from the whole Element, ſhould be
duced into a Globe: Which is not ſeen to happen; though indeed
the Senſes may ſee, and the Underſtanding perceive that the
lement of Water loving to form it ſelf into a Spherical Figure
about the common centre of gravity, to which all grave
dies tend (that is, the centre of the Terreſtrial Globe) it
therein is followed by all its parts, according to the Axiome;
ſo that all the ſurfaces of Seas, Lakes, Pools, and in a word,
of all the parts of Waters conteined in veſſels, diſtend
themſelves into a Spherical Figure, but that Figure is an arch
of that Sphere that hath for its centre the centre of the
reſtrial Globe, and do not make particular Spheres of
ſelves.
The vain
mentation of ſome
to prove the
ment of Water to
be of a Spherical
ſuper ficies.
SALV. The errour indeed is childiſh; and if it had
been onely the ſingle miſtake of Sacroboſco, I would eaſily
have allowed him in it; but to pardon it alſo to his
mentators, and to other famous men, and even to Ptolomy
1himſelfe; this I cannot do, without bluſhing for their
tation. But it is high time to take leave, it row being
very late, and we being to meet again to morrow,
at the uſual hour, to bring all the foregoing
Diſcourſes to a final
122[Figure 22]23[Figure 23]24[Figure 24]25[Figure 25]26[Figure 26]27[Figure 27]28[Figure 28]29[Figure 29]
Place this Plate
at the end of
the thirdDialogue
1
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1
GALILÆUS
Gailæus Lyncæus,
HIS
SYSTEME
OF THE
WORLD.
The Fourth Dialogue.
INTERLOCVTORS.
SALVIATUS, SAGREDUS, & SIMPLICIUS.
SAGR. I know not whether your return to our
accuſtomed conferences hath really been
later than uſual, or whether the deſire
of hearing the thoughts of Salviatus,
touching a matter ſo curious, hath
made me think it ſo: But I have
ried a long hour at this window,
cting every moment when the Gondola
would appear that I ſent to fetch you.
SALV. I verily believe that your imagination more than our
tarriance hath prolonged the time: and to make no longer

murre, it would be well, if without interpoſing more words, we
came to the matter it ſelf; and did ſhew, that nature hath
mitted (whether the buſineſs in rei veritate be ſo, or elſe to play
1and ſport with our Fancies) hath, I ſay, hath permitted that the

motions for every other reſpect, except to reſolve the ebbing and
flowing of the Sea, aſſigned long ſince to the earth, ſhould be found
now at laſt to anſwer exactly to the cauſe thereof; and, as it

were, with mutual a emulation, the ſaid ebbing and flowing
to appear in confirmation of the Terreſtrial motion: the judices
whereof have hitherto been taken from the cœleſtial Phænomena,
in regard that of thoſe things that happen on Earth, not any one
was of force to prove one opinion more than another, as we
ready have at large proved, by ſhewing that all the terrene
rences upon which the ſtability of the Earth and mobility of the
Sun and Firmament is commonly inferred, are to ſeem to us
formed in the ſame manner, though we ſuppoſed the mobility of
the Earth, and the immobility of them. The Element of
ter onely, as being moſt vaſt, and which is not annexed and
catenated to the Terreſtrial Globe as all its other ſolid parts are;
yea, rather which by reaſon of its fluidity remaineth apart ſui
juris, and free, is to be ranked amongſt thoſe ſublunary things,
from which we may collect ſome hinte and intimation of what the
Earth doth in relation to motion and reſt. After I had many
and many a time examined with my ſelf the effects and accidents,
partly ſeen and partly underſtood from others, thar are to be
ſerved in the motions of waters: and moreover read and heard
the great vanities produced by many, as the cauſes of thoſe
dents, I have been induced upon no ſlight reaſons to omit theſe

two concluſions (having made withal the neceſſary
ſals) that in caſe the terreſtrial Globe be immoveable, the flux
and reflux of the Sea cannot be natural; and that, in caſe thoſe
motions be conferred upon the ſaid Globe, which have been long
ſince aſſigned to it, it is neceſſary that the Sea be ſubject to
bing and flowing, according to all that which we obſerve to
pen in the ſame.
Nature in ſport
maketh the ebbing
and flowing of the
Sea, to approve the
Earths mobility.
The tide, and
mobility of the
Earth mutually
confirm each other
All terrene
fects, indifferently
confirm the motion
or reſt of the
Earth, except the
ebbing and flowing
of the Sea.
The firſt
ral concluſion of
the impoſſibility of
the ebbing and
flowing the
bility of the
ſtrial Globe being
granted.
SAGR. The Propoſition is very conſiderable, as well for it
ſelf as for what followeth upon the ſame by way of conſequence,
ſo that I ſhall the more intenſly hearken to the explanation and
confirmation of
The knowledge
of the offests
tributes to the
veſtigation of the
cauſes.
SALV. Becauſe in natural queſtions, of which number this
which we have in hand is one, the knowledge of the effects is a
means to guide us to the inveſtigation and diſcovery of the
ſes, and without which we ſhould walk in the dark, nay with
more uncertainty, for that we know not whither we would go,
whereas the blind, at leaſt, know where they deſire to arrive;
fore firſt of all it is neceſſary to know the effects whereof we
quire the cauſes: of which effects you, Sagredus, ought more
abundantly and more certainly to be informed than I am,
1as one, that beſides your being born, and having, for a long
time, dwelt in Venice, where the Tides are very notable for their
greatneſſe, have alſo ſailed into Syria, and, as an ingenuous and
apprehenſive wit, muſt needs have made many Obſervations
on this ſubject: whereas I, that could onely for a time, and that
very ſhort, obſerve what happened in theſe extream parts of the
Adriatick Gulph, and in our Seas below about the Tyrrhene
ſhores, muſt needs take many things upon the relation of
thers, who, for the moſt part, not very well agreeing, and
ſequently being very uncertain, contribute more of confuſion
than confirmation to our ſpeculations. Nevertheleſſe, from thoſe
that we are ſure of, and which are the principal, I think I am
ble to attain to the true and primary cauſes; not that I pretend
to be able to produce all the proper and adequate reaſons of
thoſe effects that are new unto me, and which conſequently I
could never have thought upon. And that which I have to ſay,
I propoſe only, as a key that openeth the door to a path never
yet trodden by any, in certain hope, that ſome wits more
lative than mine, will make a further progreſſe herin, and
trate much farther than I ſhall have done in this my firſt
very: And although that in other Seas, remote from us, there may
happen ſeveral accidents, which do not happen in our
ranean Sea, yet doth not this invalidate the reaſon and cauſe that
I ſhall produce, if ſo be that it veriſie and fully reſolve the
cidents which evene in our Sea: for that in concluſion there can
be but one true and primary cauſe of the effects that are of the
ſame kind. I will relate unto you, therefore, the effects that I
know to be true, and aſſigne the cauſes thereof that I think
to be true, and you alſo, Gentlemen, ſhall produce ſuch
others as are known to you, beſides mine, and then we will
try whether the cauſe, by me alledged, may ſatisfie them
alſo.
Three Periods
of ebbings and
flowings, diurnal,
monethly, and
nual.
I therefore affirm the periods that are obſerved in the fluxes
and refluxes of the Sea-waters to be three: the firſt and
pal is this great and moſt obvious one; namely, the diurnal,
ding to which the intervals of ſome hours with the waters flow and
ebbe; and theſe intervals are, for the moſt part, in the
rane from ſix hours to ſix hours, or thereabouts, that is, they for
ſix hours flow, and for ſix hours ebbe. The ſecond period is
monethly, and it ſeemes to take its origen from the motion of
the Moon, not that it introduceth other motions, but only
tereth the greatneſſe of thoſe before mentioned, with a notable
difference, according as it ſhall wax or wane, or come to the
Quadrature with the Sun. The third Period is annual, and is
ſeen to depend on the Sunne, and onely altereth the diurnal
1motions, by making them different in the times of the
ſtices, as to greatneſſe, from what they are in the Equinoxes.
We will ſpeak (in the firſt place, of the diurnal motion, as
being the principal, and upon which the Moon and Sun ſeem to
exerciſe their power ſecondarily, in their monethly and annual

alterations. Three differences are obſervable in theſe horary
mutations; for in ſome places the waters riſe and fall, without
making any progreſſive motion; in others, without riſing or
ling they run one while towards the Eaſt, and recur another
while towards the Weſt; and in others they vary the heights
and courſe alſo, as happeneth here in Venice, where the Tides in
coming in riſe, and in going out fall; and this they do in the
termities of the lengths of Gulphs that diſtend from Weſt to
Eaſt, and terminate in open ſhores, up along which ſhores the
Tide at time of flood hath room to extend it ſelf: but if the
courfe of the Tide were iutercepted by Cliffes and Banks of
great height and ſteepneſſe, there it will flow and ebbe without
any progreſſive motion. Again, it runs to and again, without
changing height in the middle parts of the Mediterrane, as

bly happeneth in the ^{*} Faro de Meſſina, between Scylla and
rybdis, where the Currents, by reaſon of the narrowneſſe of
the Channel, are very ſwift; but in the more open Seas, and
about the Iſles that ſtand farther into the Mediterranean Sea, as

the Baleares, Corſica, Sardignia, ^{*} Elba, Sicily towards the Affrican

Coaſts, Malta, ^{*} Candia, &c. the changes of watermark are
very ſmall; but the currents indeed are very notable, and
cially when the Sea is pent between Iſlands, or between them
and the Continent.
Varieties that
happen in the
nal period.
* A Strait, ſo
called.
* Or Ilva.
* Or Creta.
Now theſe onely true and certain effects, were there no more
to be obſerved, do, in my judgment, very probably perſwade
any man, that will contain himſelf within the bounds of
ral cauſes, to grant the mobility of the Earth: for to make the
veſſel (as it may be called) of the Mediterrane ſtand ſtill, and to
make the water contained therein to do, as it doth, exceeds my
imagination, and perhaps every mans elſe, who will but pierce
beyond the rinde in theſe kind of inquiries.
SIMP. Theſe accidents, Salviatus, begin not now, they are
moſt ancient, and have been obſerved by very many, and ſeveral
have attempted to aſſigne, ſome one, ſome another cauſe for the
ſame: and there dwelleth not many miles from hence a famous
Peripatetick, that alledgeth a cauſe for the ſame newly fiſhed out

of a certain Text of Ariſtotle, not well underſtood by his
poſitors, from which Text he collecteth, that the true cauſe of
theſe motions doth only proceed from the different profundities
of Seas: for that the waters of greateſt depth being greater in
1abundance, and therefore more grave, drive back the Waters
of leſſe depth, which being afterwards raiſed, deſire to
ſcend, and from this continual colluctation or conteſt proceeds

the ebbing and flowing. Again thoſe that referre the ſame to the
Moon are many, ſaying that ſhe hath particular Dominion over
the Water; and at laſt a certain Prelate hath publiſhed a little
Treatiſe, wher in he ſaith that the Moon wandering too and
fro in the Heavens attracteth and draweth towards it a Maſſe of
Water, which goeth continually following it, ſo that it is full Sea
alwayes in that part which lyeth under the Moon; and becauſe,
that though ſhe be under the Horizon, yet nevertheleſſe the Tide
returneth, he ſaith that no more can be ſaid for the ſalving of that
particular, ſave onely, that the Moon doth not onely naturally
retain this faculty in her ſelf; but in this caſe hath power to
fer it upon that degree of the Zodiack that is oppoſite unto it.
Others, as I believe you know, do ſay that the Moon is able

with her temperate heat to rarefie the Water, which being
refied, doth thereupon flow. Nor hath there been wanting ſome
that ----
The cauſe of the
abbing and flowing
alledged by a
tain modern
loſopher.
The cauſe of
the ebbing and
flowing aſcribed to
the Moon by a
certain Prelate.
Hieronymus
rius and other
ripateticks refer it
to the temperate
heat of the Moon.
SAGR. I pray you Simplicius let us hear no more of them,
for I do not think it is worth the while to waſt time in relating
them, or to ſpend our breath in confuting them; and for your
part, if you gave your aſſent to any of theſe or the like
ries, you did a great injury to your judgment, which
leſſe I acknowledg to be very piercing.
SALV. But I that am a little more flegmatick than you, Sagre-

dus, will ſpend a few words in favour of Simplicius, if haply
he thinks that any probability is to be found in thoſe things that
he hath related. I ſay therefore: The Waters, Simplicius, that
have their exteriour ſuperficies higher, repel thoſe that are
riour to them, and lower; but ſo do not thoſe Waters that are
of greateſt profundity; and the higher having once driven back
the lower, they in a ſhort time grow quiet and ^{*} level. This

your Peripatetick muſt needs be of an opinion, that all the Lakes
in the World that are in a calme, and that all the Seas where
the ebbing and flowing is inſenſible, are level in their bottoms;
but I was ſo ſimple, that I perſwaded my ſelf that had we no

ther plummet to ſound with, the Iſles that advance ſo high
bove Water, had been a ſufficient evidence of the unevenneſſe
of their bottomes. To that Prelate I could ſay that the Moon
runneth every day along the whole Mediterrane, and yet its
Waters do not riſe thereupon ſave onely in the very extream
bounds of it Eaſtward, and here to us at Venice. And for thoſe
that make the Moons temperate heat able to make the Water
ſwell, bid them put fire under a Kettle full of Water, and hold
1their right hand therein till that the Water by reaſon of the heat
do riſe but one ſole inch, and then let them take it out, and
write off the tumefaction of the Sea. Or at leaſt deſire them to
ſhew you how the Moon doth to rarefie a certain part of the
Waters, and not the remainder; as for inſtance, theſe here of
Venice, and not thoſe of Ancona, Naples, Genova: the truth is

Poetick Wits are of two kinds, ſome are ready and apt to
invent Fables, and others diſpoſed and inclined to believe them.
Anſwers to the
vanities alledged
as cauſes of the
bing and flowing.
+ Or rather
ſmooth.
The Iſles are
kens of the
venneſſe of the
bottomes of Seas.
Poetick wits of
two kinds.
SIMP. I believe that no man believeth Fables, ſo long as he
knows them to be ſo; and of the opinions concerning the cauſes
of ebbing and flowing, which are many, becauſe I know that of
one ſingle effect there is but one ſingle cauſe that is true and
mary, I underſtand very well, and am certain that but one alone
at the moſt can be true, and for all the reſt I am ſure that they are
fabulous, and falſe; and its poſſible that the true one may not be
among thoſe that have been hitherto produced; nay I verily
lieve that it is not, for it would be very ſtrange that the truth

ſhould have ſo little light, as that it ſhould not be viſible amongſt
the umbrages of ſo many falſhoods. But this I ſhall ſay with the
liberty that is permitted amongſt us, that the introduction of the
Earths motion, and the making it the cauſe of the ebbing and
flowing of Tides, ſeemeth to me as yet a conjecture no leſſe
bulous than the reſt of thoſe that I have heard; and if there
ſhould not be propoſed to me reaſons more conformable to
ral matters, I would without any more ado proceed to believe
this to be a ſupernatural effect, and therefore miraculous, and
unſearchable to the underſtandings of men, as infinite others there
are, that immediately depend on the Omnipotent hand of
Truth hath not
ſo little light as
not to be
ed amidſt the
brages of
ſhoods.
Ariſtotle holdeth
thoſe effects to be
miraculous, of
which the cauſes
are unknown.
SAGR. You argue very prudently, and according to the
Doctrine of Ariſtotle, who you know in the beginning of his
mechanical queſtions referreth thoſe things to a Miracle, the
cauſes whereof are occult. But that the cauſe of the ebbing and
flowing is one of thoſe that are not to be found out, I believe
you have no greater proof than onely that you ſee, that amongſt
all thoſe that have hitherto been produced for true cauſes
of, there is not one wherewith, working by what artifice you
will, we are able to repreſent ſuch an effect; in regard that
ther with the light of the Moon nor of the Sun, nor with
temperate heats, nor with different profundities, ſhall one ever
artificially make the Water conteined in an immoveable Veſſel
to run one way or another, and to ebbe and flow in one place,
and not in another. But if without any other artifice, but with
the onely moving of the Veſſel, I am able punctually to
ſent all thoſe mutations that are obſerved in the Sea Water, why
will you refuſe this reaſon and run to a Miracle?
1
SIMP. I will run to a Miracle ſtill, if you do not with ſome
other natural cauſes, beſides that of the motion of the Veſſels of
the Sea-water diſſwade me from it; for I know that thoſe Veſſels
move not, in regard that all the entire Terreſtrial Globe is
rally immoveable.
SALV. But do not you think, that the Terreſtrial Globe might
ſupernaturally, that is, by the abſolute power of God, be made
moveable? SIMP. Who doubts it?
SALV. Then Simplicius, ſeeing that to make the flux and
reflux of the Sea, it is neceſſary to introduce a Miracle, let us
ſuppoſe the Earth to move miraculouſly, upon the motion of
which the Sea moveth naturally: and this effect ſhall be alſo the
more ſimple, and I may ſay natural, amongſt the miraculous
perations, in that the making a Globe to move round, of which
kind we ſee many others to move, is leſſe difficult than to make
an immenſe maſſe of water go forwards and backwards, in one
place more ſwiftly, and in another leſſe, and to riſe and fall in
ſome places more; in ſome leſſe, and in ſome not at all: and to
work all theſe different effects in one and the ſame Veſſel that
containeth it: beſides, that theſe are ſeveral Miracles, and that
is but one onely. And here it may be added, that the Miracle
of making the water to move is accompanied with another,
namely, the holding of the Earth ſtedfaſt againſt impetuosities
of the water, able to make it ſwage ſometimes one way, and
ſometimes another, if it were not miraculouſly kept to rights.
SAGR. Good Simplicius, let us for the preſent ſuſpend our
judgement about ſentencing the new opinion to be vain that
viatus is about to explicate unto us, nor let us ſo haſtily flye out
into paſſion like the ſcolding overgrown Haggs: and as for the
Miracle, we may as well recurre to it when we have done
ring the Diſcourſes contained within the bounds of natural
ſes: though to ſpeak freely, all the Works of nature, or rather
of God, are in my judgement miraculous.
SALV. And I am of the ſame opinion; nor doth my ſaying,
that the motion of the Earth is the Natural cauſe of the ebbing
and flowing, hinder, but that the ſaid motion of the Earth may
be miraculous. Now reaſſuming our Argument, I apply, and
once again affirm, that it hath been hitherto unknown how it
might be that the Waters contained in our Mediterranean
Straights ſhould make thoſe motions, as we ſee it doth, if ſo be
the ſaid Straight, or containing Veſſel were immoveable. And
that which makes the difficulty, and rendreth this matter
cable, are the things which I am about to ſpeak of, and which
are daily obſerved. Therefore lend me your attention.
We are here in Venice, where at this time the Waters are low,
1

the Sea calm, the Air tranquil; ſuppoſe it to be young flood,
and that in the term of five or ſix hours the water do riſe ten
^{*} hand breadths and more; that riſe is not made by the firſt
water, which was ſaid to be rarefied, but it is done by the
ſion of new Water: Water of the ſame ſort with the former,

of the ſame brackiſhneſs, of the ſame denſity, of the ſame
weight: Ships, Simplicius, float therein as in the former,
out drawing an hairs breadth more water; a Barrel of this ſecond
doth not weigh one ſingle grain more or leſs than ſuch another
quantity of the other, and retaineth the ſame coldneſs without
the leaſt alteration: And it is, in a word, Water newly and

bly entred by the Channels and Mouth of the ^{*} Lio. Conſider
now, how and from whence it came thither. Are there happly
hereabouts any Gulphs or Whirle pools in the bottom of the
Sea, by which the Earth drinketh in and ſpueth out the Water,
breathing as it were a great and monſtruous Whale? But if this
be ſo, how comes it that the Water doth not flow in the ſpace of
ſix hours in Ancona, in ^{*} Raguſa, in Corfu, where the Tide is
ry ſmall, and happly unobſervable? Who will invent a way to
pour new Water into an immoveable Veſſel, and to make that
it riſe onely in one determinate part of it, and in other places
not? Will you ſay, that this new Water is borrowed from the
Ocean, being brought in by the Straight of Gibraltar? This
will not remove the doubt aforeſaid, but will beget a greater.
And firſt tell me what ought to be the current of that Water,
that entering at the Straights mouth, is carried in ſix hours to
the remoteſt Creeks of the Mediterrane, at a diſtance of two
or three thouſand Miles, and that returneth the ſame ſpace again
in a like time at its going back? What would Ships do that lye out
at Sea? What would become of thoſe that ſhould be in the
Straights-mouth in a continual precipice of a vaſt accumulation of
Waters, that entering in at a Channel but eight Mile, broad, is to
give admittance to ſo much Water as in ſix hours over-floweth a
tract of many hundred Miles broad, & thouſands in length? What
Tygre, what Falcon runneth or flyeth with ſo much ſwiftneſs?
With the ſwiftneſs, I ſay, of above 400 Miles an hour. The
rents run (nor can it be denied) the long-wayes of the Gulph, but
ſo ſlowly, as that a Boat with Oars will out-go them, though
deed not without defalking for their wanderings. Moreover, if this
Water come in at the Straight, the other doubt yet remaineth,
namely, how it cometh to flow here ſo high in a place ſo remote,
without firſt riſing a like or greater height in the parts more
cent? In a word, I cannot think that either obſtinacy, or ſharpneſs
of wit can ever find an anſwer to theſe Objections, nor
quently to maintain the ſtability of the Earth againſt them,
ing within the bounds of Nature.
1
It is proved
impoſſible that
there ſhould
rally be any ebbing
and flowing, the
Earth being
moveable.
* Palms.
+ Lio is a fair
Port in the
tian Gulph, lying
N. E. from the
City.
SAGR. I have all the while perfectly apprehended you in this;
and I ſtand greedily attending to hear in what manner theſe
ders may occur without obſtruction from the motion already
ſigned to the Earth.
SALV. Theſe effects being to enſue in conſequence of the
tions that naturally agree with the Earth, it is neceſſary that they
not onely meet with no impediment or obſtacle, but that they do
follow eaſily, & not onely that they follow with facility, but with
neceſſity, ſo as that it is impoſſible that it ſhould ſucceed otherwiſe,
for ſuch is the property & condition of things natural & true.

ving therefore ſhewen the impoſſibility of rendring a reaſon of the
motions diſcerned in the Waters, & at the ſame time to maintain
the immobility of the veſſel that containeth them: we may proceed
to enquire, whether the mobility of the Container may produce
the required effect, in the manner that it is obſerved to evene.
True and
ral effects follow
without difficulty.
Two kinds of motions may be conferred upon a Veſſel,

by the Water therein contained, may acquire a faculty of
ctuating in it, one while towards one ſide, and another while
towards another; and there one while to ebbe, and another
while to flow. The firſt is, when firſt one, and then another of
thoſe ſides is declined, for then the Water running towards the
inclining ſide, will alternately be higher and lower, ſometimes
on one ſide, and ſometimes on another. But becauſe that this
riſing and abating is no other than a receſſion and acceſſion to the
centre of the Earth, ſuch a motion cannot be aſcribed to the
ties of the ſaid Earth, that are the Veſſels which contain the
ters; the parts of which Veſſel cannot by any whatſoever motion
aſſigned to the Earth, be made to approach or recede from the

centre of the ſame: The other ſort of motion is, when the
Veſſel moveth (without inclining in the leaſt) with a progreſſive
motion, not uniform, but that changeth velocity, by ſometimes
accellerating, and other times retarding: from which diſparity

it would follow, that the Water contained in the Veſſel its true,
but not fixed faſt to it, as its other ſolid parts, but by reaſon of
its fluidity, as if it were ſeparated and at liberty, and not
ged to follow all the mutations of its Container, in the retardation
of the Veſſel, it keeping part of the impetus before conceived,
would run towards the the preceding part, whereupon it would
of neceſſity come to riſe; and on the contrary, if new velocity
ſhould be added to the Veſſel, with retaining parts of its tardity,
ſtaying ſomewhat behind, before it could habituate it ſelf to the
new impetus, it would hang back towards the following part,
where it would come to riſe ſomething. The which effects we
may plainly declare and make out to the Senſe by the example of
one of thoſe ſame Barks yonder, which continually come from
1
^{*} Lizza-Fuſina, laden with freſh water, for the ſervice of the City.
Let us therefore fancy one of thoſe Barks, to come from thence
with moderate velocity along the Lake, carrying the water gently,
of which it is full: and then either by running a ground, or by
ſome other impediment that it ſhall meet with, let it be notably
retarded. The water therein contained ſhall not, by that means,
loſe, as the Bark doth, its pre-conceived impetus, but retaining
the ſame, ſhall run forwards towards the prow, where it ſhall
riſe notably, falling as much a ſtern. But if, on the contrary,
the ſaid Bark, in the midſt of its ſmooth courſe, ſhall have a new
velocity, with notable augmentation added to it, the water
tained before it can habituate it ſelf thereto, continuing in its
tardity, ſhall ſtay behinde, namely a ſtern, where of
quence it ſhall mount, and abate for the ſame at the prow. This
effect is undoubted and manifeſt, and may hourly be
ted; in which I deſire that for the preſent three particulars may
be noted. The flrſt is, that to make the water to riſe on one
ſide of the veſſel, there is no need of new water, nor that it run
thither, forſaking the other ſide. The ſecond is, that the water
in the middle doth not riſe or fall notably, unleſſe the courſe of
the Bark were not before that very ſwift, and the ſhock or other
arreſt that held it exceeding ſtrong and ſudden, in which caſe its
poſſible, that not only all the water might run forwards, but
that the greater part thereof might iſſue forth of the Bark: and
the ſame alſo would enſue, whilſt that being under ſail in a
ſmooth courſe, a moſt violent impetus ſhould, upon an inſtant,
overtake it: But when to its calme motion there is added a
derate retardation or incitation, the middle parts (as I ſaid)
obſervedly riſe and fall: and the other parts, according as they
are neerer to the middle, riſe the leſſe; and the more remote,
more. The third is, that whereas the parts about the midſt do
make little alteration in riſing and falling, in reſpect of the
ters of the ſides; on the contrary, they run forwards and
wards very much, in compariſon of the extreams. Now, my
Maſters, that which the Bark doth, in reſpect of the water by it
contained, and that which the water contained doth, in
ſpect of the Bark its container, is the ſelf-ſame, to an hair, with
that which the Mediterranean Veſſel doth, in reſpect of the
ters in it contained, and that which the waters contained do, in

reſpect of the Mediterranean Veſſel their container. It
eth now that we demonſtrate how, and in what manner it is true,
that the Mediterrane, and all the other Straits; and in a word,
all the parts of the Earth do all move, with a motion notably
uneven, though no motion that is not regular and uniforme, is
thereby aſſigned to all the ſaid Globe taken collectively.
1
Two ſorts of
motions of the
taining Veſſel, may
make the
ned water to riſe
and fall.
The Cavities of
the Earth cannot
approach or go
ther from the
tre of the ſame.
The progpeſſive
and uneven motion
may make the
ter contained in a
Veſſel to run to
and fro.
+ A Town
ing S. E. of Venice
The parts of the
terreſtrial Globe
accelerate and
tard in their
on.
SIMP. This Propoſition, at firſt ſight to me, that am neither
Geometrician nor Aſtronomer, hath the appearance of a very
great Paradox; and if it ſhould be true, that the motion of the
whole, being regular, that of the parts, which are all united to
their whole, may be irregular, the Paradox will overthrow the
Axiome that affirmeth, Eandem eſſe rationem totius &
tium.
SALV. I will demonſtrate my Paradox, and leave it to your
care, Simplicius, to defend the Axiome from it, or elſe to
concile them; and my demonſtration ſhall be ſhort and
miliar, depending on the things largely handled in our
dent conferences, without introducing the leaſt ſyllable, in
vour of the flux and reflux.
We have ſaid, that the motions aſſigned to the Terreſtrial

Globe are two, the firſt Annual, made by its centre about the
circumference of the Grand Orb, under the Ecliptick, according
to the order of the Signes, that is, from Weſt to Eaſt; the other
made by the ſaid Globe revolving about its own centre in twenty
four hours; and this likewiſe from Weſt to Eaſt: though
bout an Axis ſomewhat inclined, and not equidiſtant from that
of the Annual converſion. From the mixture of theſe two
tions, each of it ſelf uniform, I ſay, that there doth reſult an
uneven and deformed motion in the parts of the Earth. Which,
that it may the more eaſily be underſtood, I will explain, by
drawing a Scheme thereof. And firſt, about the centre A [in
Fig. 1. of this Dialogue] I will deſcribe the circumference of

the Grand Orb B C, in which any point being taken, as B,
about it as a centre we will deſcribe this leſſer circle D E F G,
repreſenting the Terreſtrial Globe; the which we will ſuppoſe
to run thorow the whole circumference of the Grand Orb, with
its centre B, from the Weſt towards the Eaſt, that is, from the
part B towards C; and moreover we will ſuppoſe the
ſtrial Globe to turn about its own centre B likewiſe from Weſt
to Eaſt, that is, according to the ſucceſſion of the points
D E F G, in the ſpace of twenty four hours. But here we
ought carefully to note, that a circle turning round upon its
own centre, each part of it muſt, at different times, move with
contrary motions: the which is manifeſt, conſidering that whilſt
the parts of the circumference, about the point D move to the
left hand, that is, towards E, the oppoſite parts that are about F,
approach to the right hand, that is, towards G; ſo that when
the parts D ſhall be in F, their motion ſhall be contrary to what
it was before. when it was in D. Furthermore, the ſame time
that the parts E deſcend, if I may ſo ſpeak, towards F, thoſe in
G aſcend towards D. It being therefore preſuppoſed, that
1
there are ſuch contrarieties of motions in the parts of the
ſtrial Surface, whilſt it turneth round upon its own centre, it is
neceſſary, that in conjoyning this Diurnal Motion, with the other
Annual, there do reſult an abſolute motion for the parts of the
ſaid Terreſtrial Superficies, one while very accelerate, and
ther while as ſlow again. The which is manifeſt, conſidering
firſt the parts about D, the abſolute motion of which ſhall be
extream ſwift, as that which proceedeth from two motions made
both one way, namely, towards the left hand; the firſt of
which is part of the Annual Motion, common to all the parts of
the Globe, the other is that of the ſaid point D., carried likewiſe
to the left, by the Diurnal Revolution; ſo that, in this caſe, the
Diurnal motion increaſeth and accelerateth the Annual. The
contrary to which happeneth in the oppoſite part F, which, whilſt
it is by the common annual motion carried, together with the
whole Globe, towards the left, it happeneth to be carried by the
Diurnal converſion alſo towards the right: ſo that the
nal motion by that means detracteth from the Annual,
upon the abſolute motion, reſulting from the compoſition of both
the other, is much retarded. Again, about the points E and G,
the abſolute motion becometh in a manner equal to the ſimple
Annual one, in regard that little or nothing increaſeth or
niſheth it, as not tending either to the left hand, or to the right,
but downwards and upwards. We will conclude therefore, that
like as it is true, that the motion of the whole Globe, and of
each of its parts, would be equal and uniforme, in caſe they did
move with one ſingle motion, whether it were the meer Annual,
or the ſingle Diurnal Revolution, ſo it is requiſite, that mixing
thoſe two motions together, there do reſult thence for the parts
of the ſaid Globe irregular motions, one while accelerated, and
another while retarded, by means of the additions or
ons of the Diurnal converſion from the annual circulation. So
that, if it be true (and moſt true it is, as experience proves) that
the acceleration and retardation of the motion of the
ſel, makes water contained therein to run to and again the long
waves of it, and to riſe and fall in its extreames, who will make
ſcruple of granting, that the ſaid effect may, nay ought to
ceed in the Sea-waters, contained within their Veſſels, ſubject to
ſuch like alterations, and eſpecially in thoſe that diſtend
ſelves long-wayes from Weſt to Eaſt, which is the courſe that

the motion of thoſe ſame Veſſels ſteereth? Now this is the
moſt potent and primary cauſe of the ebbing and flowing,
out the which no ſuch effect would enſue. But becauſe the
ticular accidents are many and various, that in ſeveral places and
times are obſerved, which muſt of neceſſity have dependance
1on other different concomitant cauſes, although they ought all
to have connexion with the primary; therefore it is convenient
that we propound and examine the ſeveral accidents that may
be the cauſes of ſuch different effects.
Demonſtrations
how the parts of
the terreſtriall
Globe accelerats
and ratard.
The parts of a
Circle regularly
moved about its
own centre move in
divers times with
contrary motions.
The mixture of
the two motions
annnal and
nal, cauſeth the
inequality in the
motion of the parts
of the terreſtrial
Globe.
The moſt potent
and primary cauſe
of the ebbing and
flowing.
The firſt of which is, that when ever the water, by means of a

notable retardation or acceleration of the motion of the Veſſel,
its container, ſhall have acquired a cauſe of running towards this

or that extream, and ſhall be raiſed in the one, and abated in the

other, it ſhall not nevertheleſſe continue, for any time in that
ſtate, when once the primary cauſe is ceaſed: but by vertue of
its own gravity and natural inclination to level and grow, even it
ſhall ſpeedily return backwards of its own accord, and, as being
grave and fluid, ſhall not only move towards Æquilibrium; but
being impelled by its own impetus, ſhall go beyond it, riſing in
the part, where before it was loweſt; nor ſhall it ſtay here, but
returning backwards anew, with more reiterated reciprocations of
its undulations, it ſhall give us to know, that it will not from a
velocity of motion, once conceived, reduce it ſelf, in an inſtant,
to the privation thereof, and to the ſtate of reſt, but will
ſively, by decreaſing a little and a little, reduce it ſelf unto the
ſame, juſt in the ſame manner as we ſee a weight hanging at a
cord, after it hath been once removed from its ſtate of reſt, that
is, from its perpendicularity, of its own accord, to return thither
and ſettle it ſelf, but not till ſuch time as it ſhall have often
paſt to one ſide, and to the other, with its reciprocall
brations.
Sundry accidents
that happen in the
ebbings & flowings
The first
dent.
The Water
ſed in one end of
the Veſſel
eth of its ſelf to
Æquilibrium.
The ſecond accident to be obſerved is, that the

declared reciprocations of motion come to be made and repeated
with greater or leſſer frequency, that is, under ſhorter or longer
times, according to the different lengths of the Veſſels
ing the waters; ſo that in the ſhorter ſpaces the
ons are more frequent, and in the longer more rare: juſt as in
the former example of pendent bodies, the vibrations of thoſe
that are hanged to longer cords are ſeen to be leſſe frequent,
than thoſe of them that hang at ſhorter ſtrings.
In the ſhorter
Viſſels the
tions of waters are
more frequent.
And here, for a third obſervation, it is to be noted, that not

onely the greater or leſſer length of the Veſſel is a cauſe that
the water maketh its reciprocations under different times; but
the greater or leſſer profundity worketh the ſame effect. And
it happeneth, that of waters contained in receptacles of equall
length, but of unequal depth, that which ſhall be the deepeſt,
maketh its undulations under ſhorter times, and the
ons of the ſhallower waters are leſſe frequent.
The greater
profundity maketh
the undulations of
waters more
quent.
Fourthly, there are two effects worthy to be noted, and
ligently obſerved, which the water worketh in thoſe its
1
tions; the one is its riſing and falling alternately towards the
one and other extremity; the other is its moving and running, to
ſo ſpeak, Horizontally forwards and backwards. Which two
ferent motions differently reſide in divers parts of the Water:
for its extream parts are thoſe which moſt eminently riſe and fall;
thoſe in the middle never abſolutely moving upwards and
wards, of the reſt ſucceſſively thoſe that are neereſt to the
treams riſe and fall proportionally more than the remote: but on
the contrary, touching the other progreſſive motion forwards
and backwards, the middle parts move notably, going and
turning, and the waters that are in the extream parts gain no
ground at all; ſave onely in caſe that in their riſing they
flow their banks, and break forth of their firſt channel and
ceptacle; but where there is the obſtacle of banks to keep them
in, they onely riſe and fall; which yet hindereth not the waters
in the middle from fluctuating to and again; which likewiſe
the other parts do in proportion, undulating more or leſſe,
according as they are neerer or more remote from the
Water riſeth &
falleth in the
tream parts of the
Veſſel, and runneth
to and fro in the
midst.
An accident of
the Earths motions
impoſſible to be
duced to practice
by art.
The fifth particular accident ought the more attentively to be
conſidered, in that it is impoſſible to repreſent the effect
of by an experiment or example; and the accident is this. In
the veſſels by us framed with art, and moved, as the
named Bark, one while more, and another while leſſe ſwiftly,
the acceleration and retardation is imparted in the ſame manner
to all the veſſel, and to every part of it; ſo that whilſt v. g. the
Bark forbeareth to move, the parts precedent retard no more
than the ſubſequent, but all equally partake of the ſame
tardment; and the ſelf-ſame holds true of the acceleration,
namely, that conferring on the Bark a new cauſe of
ter velocity, the Prow and Poop both accelerate in one and
the ſame manner. But in huge great veſſels, ſuch as are the very
long bottomes of Seas, albeit they alſo are no other than
tain cavities made in the ſolidity of the Terreſtrial Globe,
it alwayes admirably happeneth, that their extreams do not
unitedly equall, and at the ſame moments of time increaſe
and diminiſh their motion, but it happeneth that when one of its
extreames hath, by vertue of the commixtion of the two
Motions, Diurnal, and Annual, greatly retarded its velocity,
the other extream is animated with an extream ſwift motion.
Which for the better underſtanding of it we will explain,
ſuming a Scheme like to the former; in which if we do but
poſe a tract of Sea to be long, v. g. a fourth part, as is the arch
B C [in Fig. 2.] becauſe the parts B are, as hath been already
declared, very ſwift in motion, by reaſon of the union of the
two motions diurnal and annual, towards one and the ſame way,
1but the part C at the ſame time is retarded in its motion, as be
ing deprived of the progreſſion dependant on the diurnal motion:
If we ſuppoſe, I ſay, a tract of Sea as long as the arch B C, we
have already ſeen, that its extreams ſhall move in the ſame time
with great inequality. And extreamly different would the
cities of a tract of Sea be that is in length a ſemicircle, and
ced in the poſition B C D, in regard that the extream B would
be in a moſt accelerate motion, and the other D, in a moſt ſlow
one; and the intermediate parts towards C, would be in a
moderate motion. And according as the ſaid tracts of Sea ſhall
be ſhorter, they ſhall leſſe participate of this extravagant
dent, of being in ſome hours of the day with their parts diverſly
affected by velocity and tardity of motion. So that, if, as in the firſt
caſe, we ſee by experience that the acceleration and retardation,
though equally imparted to all the parts of the conteining Veſſel,
is the cauſe that the water contained, fluctuates too and again, what
may we think would happen in a Veſſel ſo admirably diſpoſed,
that retardation and acceleration of motion is very unequally
contributed to its parts? Certainly we muſt needs grant that
greater and more wonderful cauſes of the commotions in the
Water ought to be looked for. And though it may ſeem
poſſible to ſome, that in artificial Machines and Veſſels we ſhould
be able to experiment the effects of ſuch an accident; yet
vertheleſſe it is not abſolutely impoſſible to be done; and I have
by me the model of an Engine, in which the effect of theſe
rable commixtions of motions may be particularly obſerved. But
as to what concerns our preſent purpoſe, that which you may
have hitherto comprehended with your imagination may
fice.
SAGR. I for my own particular very well conceive that this
admirable accident ought neceſſarily to evene in the Straights of
Seas, and eſpecially in thoſe that diſtend themſelves for a great
length from Weſt to Eaſt; namely according to the courſe of
the motions of the Terreſtrial Globe; and as it is in a certain
manner unthought of, and without a preſident among the
ons poſſible to be made by us, ſo it is not hard for me to believe,
that effects may be derived from the ſame, which are not to be
mitated by our artificial experiments.
SALV. Theſe things being declared, it is time that we
ceed to examine the particular accidents, which, together with
their diverſities, are obſerved by experience in the ebbing and
flowing of the waters. And firſt we need not think it hard to

gueſſe whence it happeneth, that in Lakes, Pooles, and alſo in the
leſſer Seas there is no notable flux and reflux; the which hath
two very ſolid reaſons. The one is, that by reaſon of the
1
neſſe of the Veſſel, in its acquiring in ſeveral hours of the day
ſeveral degrees of velocity, they are with very little difference
acquired by all its parts; for as well the precedent as the
quent, that is to ſay, both the Eaſtern and Weſtern parts, do
accelerate and retard almoſt in the ſame manner; and withal
making that alteration by little and little, and not by giving the
motion of the conteining Veſſel a ſudden check, and
ment, or a ſudden and great impulſe or acceleration; both it
and all its parts, come to be gently and equally impreſſed with
the ſame degrees of velocity; from which uniformity it
eth, that alſo the conteined water with but ſmall reſiſtance and
oppoſition, receiveth the ſame impreſſions, and by conſequence
doth give but very obſcure ſignes of its riſing or falling, or of its
running towards one part or another. The which effect is likewiſe
manifeſtly to be ſeen in the little artificial Veſſels, wherein the
contained water doth receive the ſelf ſame impreſſions of
ty; when ever the acceleration and retardation is made by gentle
and uniform proportion. But in the Straights and Bays that for a
great length diſtend themſelves from Eaſt to Weſt, the
ration and retardation is more notable and more uneven, for
that one of its extreams ſhall be much retarded in motion, and
the other ſhall at the ſame time move very ſwiftly: The
procal libration or levelling of the water proceeding from the
petus that it had conceived from the motion of its container.
The which libration, as hath been noted, hath its undulations
very frequent in ſmall Veſſels; from whence enſues, that though
there do reſide in the Terreſtrial motions the cauſe of
ring on the waters a motion onely from twelve hours to twelve
hours, for that the motion of the conteining Veſſels do
treamly accelerate and extreamly retard but once every day,
and no more; yet nevertheleſſe this ſame ſecond cauſe
ing on the gravity of the water which ſtriveth to reduce it ſelf to
equilibration, and that according to the ſhortneſſe of the
ſel hath its reciprocations of one, two, three, or more hours, this
intermixing with the firſt, which alſo it ſelf in ſmall Veſſels is
very little, it becommeth upon the whole altogether inſenſible.
For the primary cauſe, which hath the periods of twelve hours,
having not made an end of imprinting the precedent
on, it is overtaken and oppoſed by the other ſecond,
dant on the waters own weight, which according to the brevity
and profundity of the Veſſel, hath the time of its undulations of
one, two, three, four, or more hours; and this contending
with the other former one, diſturbeth and removeth it, not
mitting it to come to the height, no nor to the half of its
on; and by this conteſtation the evidence of the ebbing and
1flowing is wholly annihilated, or at leaſt very much obſcured.
I paſſe by the continual alteration of the air, which diſquieting
the water, permits us not to come to a certainty, whether any,
though but ſmall, encreaſe or abatement of half an inch, or
leſſe, do reſide in the Straights, or receptacles of water not
bove a degree or two in length.
Reaſons
ed of the
lar accidents
ſerved in the
bings and flowings.
Second cauſes
why in ſmall Seas
and in Lakes there
are no ebbings and
flowings.
I come in the ſecond place to reſolve the queſtion, why, there

not reſiding any vertue in the primary principle of commoving
the waters, ſave onely every twelve hours, that is to ſay, once
by the greateſt velocity, and once by the greateſt tardity of
motion; the ebbings and flowings ſhould yet nevertheleſſe
pear to be every ſix hours. To which is anſwered, that this
termination cannot any wayes be taken from the primary cauſe
onely; but there is a neceſſity of introducing the ſecondary
ſes, as namely the greater or leſſe length of the Veſſels, and
the greater or leſſe depth of the waters in them conteined.
Which cauſes although they have not any operation in the
ons of the waters, thoſe operations belonging to the ſole
ry cauſe, without which no ebbing or flowing would happen,
yet nevertheleſſe they have a principal ſhare in determining the
times or periods of the reciprocations, and herein their
ence is ſo powerful, that the primary cauſe muſt of force give
way unto them. The period of ſix hours therefore is no more
proper or natural than thoſe of other intervals of times, though
indeed its the moſt obſerved, as agreeing with our Mediterrane,
which was the onely Sea that for many Ages was navigated:
though neither is that period obſerved in all its parts; for
that in ſome more anguſt places, ſuch as are the
ſpont, and the Ægean Sea, the periods are much ſhorter,
and alſo very divers amongſt themſelves; for which
ſities, and their cauſes incomprehenſible to Ariſtotle, ſome
ſay, that after he had a long time obſerved it upon ſome
cliffes of Negropont, being brought to deſperation, he threw
himſelf into the adjoyning Euripus, and voluntarily drowned
himſelf.
The reaſon
ven, why the
bings and flowings,
for the moſt part,
are every ſix
hours.
In the third place we have the reaſon ready at hand, whence

it commeth to paſſe, that ſome Seas, although very long, as is
the Red Sea, are almoſt altogether exempt from Tides, which
happeneth becauſe their length extendeth not from Eaſt to
Weſt, but rather tranſverſly from the Southeaſt to the
weſt; but the motions of the Earth going from Weſt to Eaſt;
the impulſes of the water, by that means, alwayes happen to fall
in the Meridians, and do not move from parallel to parallel;
inſomuch that in the Seas that extend themſelves athwart
wards the Poles, and that the contrary way are narrow, there is
1no cauſe of ebbing and flowing, ſave onely by the participation
of another Sea, wherewith it hath communication, that is
ject to great
The cauſe why
ſome Seas, though
very long, ſuffer
no ebbing and
flowing.
Ebbings and
flowings why
teſt in the
mities of gulphs,
and leaſt in the
middle parts.
In the fourth place we ſhall very eaſily find out the reaſon
why the fluxes and refluxes are greateſt, as to the waters riſing
and falling in the utmoſt extremities of Gulphs, and leaſt in the
intermediate parts; as daily experience ſheweth here in Venice,
lying in the farther end of the Adriatick Sea, where that
rence commonly amounts to five or ſix feet; but in the places
of the Mediterrane, far diſtant from the extreams, that
on is very ſmall, as in the Iſles of Corſica and Sardinnia, and
in the Strands of Rome and Ligorne, where it exceeds not half a
foot; we ſhall underſtand alſo, why on the contrary, where
the riſings and fallings are ſmall, the courſes and recourſes are
great: I ſay it is an eaſie thing to underſtand the cauſes of theſe
accidents, ſeeing that we meet with many manifeſt occurrences
of the ſame nature in every kind of Veſſel by us artificially
poſed, in which the ſame effects are obſerved naturally to
low upon our moving it unevenly, that is, one while faſter, and
another while ſlower.
Why in narrow
places the courſe
of the waters is
more ſwift than in
larger.
Moreover, conſidering in the fifth place, that the ſame
quantity of Water being moved, though but gently, in a ſpatious
Channel, comming afterwards to go through a narrow paſſage,
will of neceſſity run, with great violence, we ſhall not finde it hard
to comprehend the cauſe of the great Currents that are made
in the narrow Channel that ſeparateth Calabria from Sicilia:
for that all the Water that, by the ſpaciouſneſſe of the Iſle,
and by the Ionick Gulph, happens to be pent in the Eaſtern
part of the Sea, though it do in that, by reaſon of its largeneſs,
gently deſcend towards the Weſt, yet nevertheleſſe, in that it
is pent up in the Boſphorus, it floweth with great violence
tween Scilla and Caribdis, and maketh a great agitation. Like to
which, and much greater, is ſaid to be betwixt Africa and the
great Iſle of St. Lorenzo, where the Waters of the two vaſt
Seas, Indian and Ethiopick, that lie round it, muſt needs be
ſtraightned into a leſſe Channel between the ſaid Iſle and the
Ethiopian Coaſt. And the Currents muſt needs be very great
in the Straights of Magellanes, which joyne together the
vaſt Oceans of Ethiopia, and Del Zur, called alſo the Pacifick
Sea.
A diſcuſſion of
ſome more abſtruſe
accidents obſerved
in the ebbing and
flowing.
It follows now, in the ſixth place, that to render a reaſon of
ſome more abſtruſe and incredible accidents, which are
ved upon this occaſion, we make a conſiderable reflection upon
the two principal cauſes of ebbings and flowings, afterwards
compounding and mixing them together. The firſt and ſimpleſt
1of which is (as hath often been ſaid) the determinate
tion and retardation of the parts of the Earth, from whence
the Waters have a determinate period put to their decurſions
towards the Eaſt, and return towards the Weſt, in the time of
twenty ſour hours. The other is that which dependeth on the
per gravity of the Water, which being once commoved by the
primary cauſe, ſeeketh, in the next place, to reduce it ſelf to
quilibrium, with iterated reciprocations; which are not
mined by one ſole and prefixed time; but have as many
ties of times as are the different lengths and profundities of the
receptacles, and Straights of Seas; and by what dependeth on
this ſecond principle, they would ebbe. and flow, ſome in one
hour, others in two, in four, in ſix, in eight, in ten, &c. Now if
we begin to put together the firſt cauſe, which hath its ſet Period
from twelve hours to twelve hours, with ſome one of the
dary, that hath its Period verb. grat. from five hours to five
hours, it would come to paſſe, that at ſometimes the primary
cauſe and ſecondary would accord to make impulſes both one
and the ſame way; and in this concurrency, and (as one may call
it) unanimous conſpiration the flowings ſhall be great. At other
times it happening that the primary impulſe doth, in a certain
manner, oppoſe that which the ſecondary Period would make,
and in this conteſt one of the Principles being taken away, that
which the other would give, will weaken the commotion of the
Waters, and the Sea will return to a very tranquil State, and
almoſt immoveable. And at other times, according as the two
aforeſaid Principles ſhall neither altogether conteſt, nor
ther concur, there ſhall be other kinds of alterations made in
the increaſe and diminution of the ebbing and flowing. It may
likewiſe fall out that two Seas, conſiderably great and which
communicate by ſome narrow Channel, may chance to have, by
reaſon of the mixtion of the two Principles of motion, one
cauſe to flow at the time that the other hath cauſe to move a
contrary way; in which caſe in the Channel, whereby they
imbogue themſelves into each other, there do extraordinary
conturbations inſue, with oppoſite and vortick motions, and
moſt dangerous boilings and breakings, as frequent relations
and experiences do aſſure us. From ſuch like diſcordant
ons, dependent not onely on the differenr poſitions and
tudes, but very much alſo upon the different profundities of the
Seas, which have the ſaid intercourſe there do happen at
times different commotions in the Waters, irregular, and that
can be reduced to no rules of obſervation, the reaſons of which
have much troubled, and alwayes do trouble Mariners, for that
they meet with them without ſeeing either impulſe of winds, or
1other eminent aereal alteration that might occaſion the ſame; of
which diſturbance of the Air we ought to make great account
in other accidents, and to take it for a third and accidental
cauſe, able to alter very much the obſervation of the effects
pending on the ſecondary and more eſſential cauſes. And it is
not to be doubted, but that impetuous windes, continuing to
blow, for example, from the Eaſt, they ſhall retein the Waters
and prohibit the reflux or ebbing; whereupon the ſecond and
third reply of the flux or tide overtaking the former, at the
hours prefixed, they will ſwell very high; and being thus born
up for ſome dayes, by the ſtrength of the Winds, they ſhall riſe
more than uſual, making extraordinary inundations.
We ought alſo, (and this ſhall ſerve for a ſeventh Probleme)
to take notice of another cauſe of motion dependant on the
great abundance of the Waters of great Rivers that diſcharge

themſelves into Seas of no great capacity, whereupon in the
Straits or Boſphori that communicate with thoſe Seas, the Waters
are ſeen to run always one way: as it happeneth in the
an Boſphorus below Conſtantinople, where the water alwayes
runneth from the Black-Sea, towards the Propontis: For in the
ſaid Black-Sea by reaſon of its ſhortneſſe, the principal cauſes
of ebbing and flowing are but of ſmall force. But, on the
trary, very great Rivers falling into the ſame, thoſe huge
fluxions of water being to paſſe and diſgorge themſelves by the

the Straight, the ^{*}courſe is there very notable and alwayes
wards the South. Where moreover we ought to take notice, that
the ſaid Straight or Channel, albeit very narrow, is not ſubject
to perturbations, as the Straight of Soilla and Carybdis; for that
that hath the Black-Sea above towards the North, and the
pontis, the Ægean, and the Mediterranean Seas joyned unto it,
though by a long tract towards the South; but now, as we have
obſerved, the Seas, though of never ſo great length, lying North
and South, are not much ſubject to ebbings and flowings; but
becauſe the Sicilian Straight is ſituate between the parts of the
Mediterrane diſtended for a long tract or diſtance from Weſt to
Eaſt, that is, according to the courſe of the fluxes and refluxes,
therefore in this the agitations are very great; and would be
much more violent between Hercules Pillars, in caſe the
Straight of Gibraltar did open leſſe; and thoſe of the Straight of
Magellanes are reported to be extraordinary violent.
The cauſe why,
in ſome narrow
Channels, we ſee
the Sea-waters run
alwayes one way.
* Or current.
This is what, for the preſent, cometh into my mind to ſay unto
you about the cauſes of this firſt period diurnal of the Tide, and
its various accidents, touching which, if you have any thing to
offer, you may let us hear it, that ſo we may afterwards
ceed to the other two periods, monethly and annual.
1
SIMP. In my opinion, it cannot be denied, but that your
courſe carrieth with it much of probability, arguing, as we ſay,
ex ſuppoſitione, namely, granting that the Earth moveth with
the two motions aſſigned it by Copernicus: but if that motion

be diſproved, all that you have ſaid is vain, and inſignificant:
and for the diſproval of that Hypotheſis, it is very manifeſtly
hinted by your Diſcourſe it ſelf. You, with the ſuppoſition of
the two Terreſtrial motions, give a reaſon of the ebbing and
flowing; and then again, arguing circularly, from the ebbing
and flowing, draw the reaſon and confirmation of thoſe very
motions; aud ſo proceeding to a more ſpecious Diſcourſe, you
ſay that the Water, as being a fluid body, and not tenaciouſly
annexed to the Earth, is not conſtrained punctually to obey
ry of its motions, from which you afterwards infer its ebbing
and flowing, Now I, according to your own method, argue
the quite contrary, and ſay; the Air is much more tenuous, and
fluid than the Water, and leſſe annexed to the Earths
es, to which the Water, if it be for nothing elſe, yet by reaſon
of its gravity that preſſeth down upon the ſame more than the
light Air, adhereth; therefore the Air is much obliged to
low the motions of the Earth: and therefore were it ſo, that the
Earth did move in that manner, we the inhabitants of it, and
carried round with like velocity by it, ought perpetually to feel
a Winde from the Eaſt that beateth upon us with intolerable
force. And that ſo it ought to fall out, quotidian experience
ſureth us: for if with onely riding poſt, at the ſpeed of eight or
ten miles an hour in the tranquil Air, the incountering of it with
our face ſeemeth to us a Winde that doth not lightly blow upon
us, what ſhould we expect from our rapid courſe of 800. or a
thouſand miles an hour, againſt the Air, that is, free from that
motion? And yet, notwithſtanding we cannot perceive any
thing of that nature.
The Hypotheſir
of the Earths
bility taken in
vour of the Tide,
oppoſed.
SALV. To this objection that hath much of likelihood in it, I

reply, that its true, the Air is of greater tenuity and levity; and,
by reaſon of its levity, leſſe adherent to the Earth than Water ſo
much more grave and ^{*}bulky; but yet the conſequence is falſe
that you infer from theſe qualities; namely, that upon account

of that its levity, tenuity, and leſſe adherence to the Earth, it
ſhould be more exempt than the Water from following the
Terreſtrial Motions; ſo as that to us, who abſolutely pertake of
of them, the ſaid exemption ſhould be ſenſible and manifeſt;
nay, it happeneth quite contrary; for, if you well remember, the
cauſe of the ebbing and flowing of the Water aſſigned by us,
conſiſteth in the Waters not following the unevenneſſe of the
motion of its Veſſel, but retaining the impetus conceived before,
1without diminiſhing or increaſing it according to the preciſe rate
of its diminiſhing or increaſing in its Veſſel. Becauſe therefore

that in the conſervation and retention of the impetus before
ceived, the diſobedience to a new augmentation or diminution of
motion conſiſteth, that moveable that ſhall be moſt apt for ſuch
a retention, ſhall be alſo moſt commodious to demonſtrate the
effect that followeth in conſequence of that retention. Now how
much the Water is diſpoſed to maintain ſuch a conceived
tion; though the cauſes ceaſe that impreſs the ſame, the
ence of the Seas extreamly diſturbed by impetuous Winds
eth us; the Billows of which, though the Air be grown calm, and
the Wind laid, for a long time after continue in motion: As the
Sacred Poet pleaſantly ſings,
The anſwer to
the objections
made againſt the
motion of the
reſtrial Globe.
+ Corpulenta.
The Water more
apt to conſerve an
impetus conceived,
then the Air.
Qual l'alto Egeo, &c.----------
And that long continuing rough after a ſtorm, dependeth on

the gravity of the water: For, as I have elſewhere ſaid, light
dies are much eaſier to be moved than the more grave, but yet
are ſo much the leſs apt to conſerve the motion imparted, when
once the moving cauſe ceaſeth. Whence it comes that the Aire,
as being of it ſelf very light and thin, is eaſily mov'd by any very
ſmall force, yet it is withall very unable to hold on its motion,
the Mover once ceaſing. Therefore, as to the Aire which
rons the Terreſtrial Globe, I would fay, that by reaſon of its
adherence, it is no leſſe carried about therewith then the Water;
and eſpecially that part which is contained in its veſſels; which

veſſels are the valleys encloſed with Mountains. And we may
with much more reaſon affirm that this ſame part of the Air is
carried round, and born forwards by the rugged parts of the
Earth, than that the higher is whirl'd about by the motion of the
Heavens, as ye Peripateticks maintain.
Light bodies eaſier
to be moved than
beavy, but leſs aut
to conſerve the
tion.
Its more rational
that the Air be
commoved by the
rugged ſurface of
the Earth than
by the Celeſtial
motion.
What hath been hitherto ſpoken, ſeems to me a ſufficient

ſwer to the allega ion of Simputius; yet nevertheleſs with a new
inſtance and ſolution, founded upon an admirable experiment, I
will ſuperabundantly ſatisfie him, and confirm to Sagredus the
mobility of the Earth. I have told you that the Air, and in
ticular that part of it which aſcendeth not above the tops of the
higheſt Mountains, is carried round by the uneven parts of the
Earths ſurface: from whence it ſhould ſeem, that it muſt of
ſequence come to paſſe, that in caſe the ſuperficies of the Earth
were not uneven, but ſmooth and plain, no cauſe would remain
for drawing the Air along with it, or at leaſt for revolving it with
ſo much uniformity. Now the ſurface of this our Globe, is not
all craggy and rugged, but there are exceeding great tracts very
1even, to wit, the ſurfaces of very vaſt Seas, which being alſo far
remote from the continuate ledges of Mountains which environ
it, ſeem to have no faculty of carrying the ſuper-ambient Air
along therewith: and not carrying it about, we may perceive what
will of conſequence enſue in thoſe places.
The revolution of
the Earth
firmed by a new
argument taken
from the Air.
SIMP. I was about to propoſe the very ſame difficulty, which
I think is of great validity.
SALV. You ſay very well Simplicius, for from the not finding
in the Air that which of conſequence would follow, did this our
Globe move round; you argue its immoveableneſſe. But in caſe
that this which you think ought of neceſſary conſequence to be
found, be indeed by experience proved to be ſo; will you accept
it for a ſufficient teſtimony and an argument for the mobility of
the ſaid Globe?
SIMP. In this caſe it is not requiſite to argue with me alone,
for if it ſhould ſo fall out, and that I could not comprehend the
cauſe thereof, yet haply it might be known by others.
SALV. So that by playing with you, a man ſhall never get, but
be alwayes on the loſing hand; and therefore it would be better
to give over: Nevertheleſs, that we may not cheat our third man
we will play on. We ſaid even now, and with ſome addition we
reitterate it, that the Ayr as if it were a thin and fluid body, and
not ſolidly conjoyned with the Earth, ſeem'd not to be
tated to obey its motion; unleſſe ſo far as the craggineſs of the
terreſtrial ſuperficies, tranſports and carries with it a part
of contigious thereunto; which doth not by any great ſpace
ceed the greateſt altitude of Mountains: the which portion of Air
ought to be ſo much leſs repugnant to the terreſtrial converſion,

by how much it is repleat with vapours, fumes, and exhalations,
matters all participating of terrene qualities, and conſequently
apt of their own nature to the ſame motions. But where there are
wanting the cauſes of motion, that is, where the ſurface of the
Globe hath great levels, and where there is leſs mixture of the
terrene vapours, there the cauſe whereby the ambient Air is
ſtrained to give entire obedience to the terreſtrial converſion will
ceaſe in part; ſo that in ſuch places, whilſt the Earth revolveth
wards the Eaſt, there will be continually a wind perceived which
will beat upon us, blowing from the Eaſt towards the Weſt:
and ſuch gales will be the more ſenſible, where the revolution of
the Globe is moſt ſwift; which will be in places more remote from
the Poles, and approaching to the greateſt Circle of the diurnal
converſion. But now de facto experience much confi meth this
Phyloſophical argumentation; for in the ſpatious Seas, and in their
parts moſt remote from Land, and ſituate under the Torrid Zone,
that is bounded by the Tropicks, where there are none of thoſe
1
ſame terreſtrial evaporations, we finde a perpetual gale move
from the Eaſt with ſo conſtant a blaſt, that ſhips by favour
of ſail proſperouſly to the West-India's. And from the ſame
coaſting along the Mexican ſhore, they with the ſame felicity paſs
the Pacifick Ocean towards the India's; which to us are Eaſt, but

to them are Weſt. Whereas on the contrary the Courſe from
thence towards the Eaſt is difficult and uncertain, and not to be
made by the ſame Rhumb, but muſt vere more to Land-ward, to
recover other Winds, which we may call accidentary and
tuary, produced from other Principles, as thoſe that inhabit the
continent find by experience. Of which productions of Winds,
the Cauſes are many and different, which ſhall not at this time be

mentioned. And theſe accidentary Winds are thoſe which blow
indifferently from all parts of the Eatth, and make rough the Seas
remote from the Equinoctial, and environed by the rugged
face of the Earth; which is as much as to ſay environ'd with
thoſe perturbations of Air, that confound that primary Gale.
The which, in caſe theſe accidental impediments were removed,
would be continually felt, and eſpecially upon the Sea. Now
ſee how the effect of the Water and Air ſeem wonderfully to
cord with the Celeſtial obſervations, to confirm the mobility of
our Terreſtrial
The vaporous
parts of the earth,
partake of its
tions.
Conſtant gales
within the
pieks blow towards
the Weſt.
The courſe to the
Weſt-India's
ſie, the return
ficult.
Winds from Land
make rough the
Seas.
Another
tion taken from the
Air in
on of the motion of
the Earth.
SAGR. I alſo for a final cloſe will relate to you one particular,
which as I believe is unknown unto you, and which likewiſe may
ſerve to confirm the ſame concluſion: You Salviatus alledged,
That Accident which Sailers meet with between the Tropicks;
I mean that perpetual Gale of Winde that beats upon them from
the Eaſt, of which I have an account from thoſe that have many
times made the Voyage: And moreover (which is very
vable) I underſtand that the Mariners do not call it a Wind, but

by another ^{*} name, which I do not now remember, taken haply
from its ſo fixed and conſtant Tenor; which when they have met
with, they tie up their ſhrouds and other cordage belonging to
the Sails, and without any more need of touching them, though
they be in a ſleep, they can continue their courſe. Now this conſtant
Trade-wind was known to be ſuch by its continual blowing
out interruptions; for if it were interrupted by other Windes, it
would not have been acknowledged for a ſingular Effect, and
different from the reſt: from which I wlll infer, That it may be
that alſo our Mediterranean Sea doth partake of the like accident;
but it is not obſerved, as being frequently altered by the
ence of other windes. And this I ſay, not without good grounds,
yea upon very probable conjectures whch came unto my
ledge, from that which tendred it ſelf to my notice on occaſion of
the voyage that I made into Syria, going Conſul for this Nation
1to Aleppo, and this it is: That keeping a particular account and

memorial of the dayes of the departure and arrival of the Ships in
the Ports of Alexandria, of Alexandretta, and this of Venice; in
comparing ſundry of them, which I did for my curioſity, I found
that in exactneſs of account the returns hither, that is the voiages
from Eaſt to Weſt along the Mediterrane, are made in leſs time
then the contrary courſes by 25. in the Hundred: So that we ſee
that one with another, the Eaſtern windes are ſtronger then the
Weſtern.
Which Wind
with our Engliſh
Mariners is called
the Trade-wind.
The voiages in the
Mediterrane from
Eaſt to Weſt are
made in ſhorter
times than from
Weſt to Eaſt.
SALV. I am very glad I know this particular, which doth not
a little make for the confirmation of the Earths mobility. And
although it may be alledged, That all the Water of the
rane runs perpetually towards the Straits-mouth, as being to
diſimbogue into the Ocean, the waters of as many Rivers, as do
diſcharge themſelves into the ſame; I do not think that that
rent can be ſo great, as to be able of it ſelf alone to make ſo
table a difference: which is alſo manifeſt by obſerving that the
water in the Pharo of Sicily runneth back again no leſs towards
the Eaſt, than it runneth forwards towards the Weſt.
SAGR. I, that have not as Simplicius, an inclination to
fie any one beſides my ſelf, am ſatisfied with what hath been ſaid
as to this firſt particular: Therefore Salviatus, when you think
it fit to proceed forward, I am prepared to hear you.
SALV. I ſhall do as you command me, but yet I would fain
hear the opinion alſo of Simplicius, from whoſe judgement I can
argue how much I may promiſe to my ſelf touching theſe
courſes from the Peripatetick Schools, if ever they ſhould come
to their ears.
SIMP. I deſire not that my opinion ſhould ſerve or ſtand for
a meaſure, whereby you ſhould judge of others thoughts; for
as I have often ſaid, I am inconſiderable in theſe kinde of ſtudies,
and ſuch things may come into the mindes of thoſe that are
ed into the deepeſt paſſages of Philoſophy, as I could never think
of; as having (according to the Proverb) ſcarce kiſt her Maid:
yet nevertheleſs, to give you my ſudden thoughts, I ſhall tell
you, That of thoſe effects by you recounted, and particularly the
laſt, there may in my judgement very ſufficient Reaſons be given
without the Earths mobility, by the mobility of the Heavens
ly; never introducing any novelty more, than the inverſion of
that which you your ſelf propoſe unto us. It hath been received

by the Peripatetick Schools, that the Element of Fire, and alſo a
great part of the Aire is carried about according to the Diurnal
converſion from Eaſt to Weſt, by the contact of the Concave of
the Lunar Orb, as by the Veſſel their container. Now without
going out of your track, I will that we determine the Quantity of
1
the Aire which partaketh of that motion to diſtend ſo low as to
the Tops of the higheſt Hills, and that likewiſe they would reach
to the Earth, if thoſe Mountains did not impede them, which
agreeth with what you ſay: For as you affirm, the Air, which is
invironed by ledges of Mountains, to be carried about by the
aſperity of the moveable Earth; we on the contrary ſay, That
the whole Element of Air is carried about by the motion of
Heaven, that part only excepted which lyeth below thoſe bodies,
which is hindred by the aſperity of the immoveable Earth. And
whereas you ſaid, That in caſe that aſperity ſhould be removed,
the Air would alſo ceaſe to be whirld about; we may ſay,
That the ſaid aſperity being removed, the whole Aire would
tinue its motion. Whereupon, becauſe the ſurfaces of ſpacious
Seas are ſmooth, and even; the Airs motion ſhall continue upon
thoſe, alwaies blowing from the Eaſt: And this is more ſenſibly
perceived in Climates lying under the Line, and within the
picks, where the motion of Heaven is ſwifter; and like as that
Celeſtial motion is able to bear before it all the Air that is at
liberty, ſo we may very rationally affirm that it contributeth the
ſame motion to the Water moveable, as being fluid and not
nected to the immobility of the Earth: And with ſo much the

more confidence may we affirm the ſame, in that by your
feſſion, that motion ought to be very ſmall in reſect of the efficient
Cauſe; which begirting in a natural day the whole Terreſtrial
Globe, paſſeth many hundreds of miles an hour, and eſpecially
towards the Equinoctial; whereas in the currents of the open Sea,
it moveth but very few miles an hour. And thus the voiages
wards the Weſt ſhall come to be commodious and expeditious,
not onely by reaſon of the perpetual Eaſtern Gale, but of the
courſe alſo of the Waters; from which courſe alſo perhaps the
Ebbing and Flowing may come, by reaſon of the different

ation of the Terreſtrial Shores: againſt which the Water coming
to beat, may alſo return backwards with a contrary motion, like
as experience ſheweth us in the courſe of Rivers; for according as
the Water in the unevenneſs of the Banks, meeteth with ſome
parts that ſtand out, or make with their Meanders ſome Reach or
Bay, here the Water turneth again, and is ſeen to retreat back
a conſiderable ſpace. Upon this I hold, That of thoſe effects
from which you argue the Earths mobility, and alledge it as a
cauſe of them, there may be aſſigned a cauſe ſufficiently valid,
retaining the Earth ſtedfaſt, and reſtoring the mobility of
Heaven.
It is
ted inverting the
argument, that
the perpetual
tion of the Air
from Eaſt to Weſt
cometh from the
motion of Heaven?
It is demonſtrated
inverting the
gument, that the
perpetual motion of
the Air from Eaſt
to Weſt, cometh
from the motion of
Heaven.
The motion of the
Water dependeth
on the motion of
Heaven.
The flux and
flux may depend
on the diurual
tion of Heaven.
SALV. It cannot be denied, but that your diſcourſe is ingenious,
& hath much of probability, I mean probability in appearance, but
not in reality & exiſtence: It conſiſteth of two parts: In the firſt it
1aſſignes a reaſon of the continual motion of the Eaſtern Winde,
and alſo of a like motion in the Water. In the ſecond, It would
draw from the ſame Sourſe the cauſe of the Ebbing and Flowing.
The firſt part hath (as I have ſaid) ſome appearance of
lity, but yet extreamly leſs then that which we take from the
Terreſtrial motion. The ſecond is not onely wholly improbable,
but altogether impoſſible and falſe. And coming to the firſt,

whereas it is ſaid that the Concave of the Moon carrieth about
the element of Fire, and the whole Air, even to the tops of the
higher Mountains. I anſwer firſt, that it is dubious whether
there be any element of Fire: But ſuppoſe there be, it is much
doubted of the Orbe of the Moon, as alſo of all the reſt; that is,
Whether there be any ſuch ſolid bodies and vaſt, or elſs, Whether
beyond the Air there be extended a continuate expanſion of a
ſubſtance of much more tenuity and purity than our Air, up and
down which the Planets go wandring, as now at laſt a good part
of thoſe very Phyloſophers begin to think: But be it in this or in

that manner, there is no reaſon for which the Fire, by a ſimple
contract to a ſuperficies, which you your ſelf grant to be ſmooth
and terſe, ſhould be according to its whole depth carried round in
a motion different from its natural inclination; as hath been
fuſely proved, and with ſenſible reaſons demonſtrated by^{+} Il Sag-

giatore: Beſides the other improbability of the ſaid motions
transfuſing it ſelf from the ſubtileſt Fire throughout the Air, much
more denſe; and from that alſo again to the Water. But that
a body of rugged and mountainous ſurface, by revolving in it
ſelf, ſhould carry with it the Air contiguous to it, and againſt
which its promontaries beat, is not onely probable but neceſſary,
and experience thereof may be daily ſeen; though without
ing it, I believe that there is no judgement that doubts thereof.
As to the other part, ſuppoſing that the motion of Heaven did
carry round the Air, and alſo the Water; yet would that motion
for all that have nothing to do with the Ebbing and Flowing.
For being that from one onely and uniform cauſe, there can

low but one ſole and uniform effect; that which ſhould be
vered in the Water, would be a continuate and uniform courſe
from Eaſt to Weſt; and in that a Sea onely, which running
paſs environeth the whole Globe. But in determinate Seas, ſuch
as is the Mediterrane ſhut up in the Eaſt, there could be no ſuch
motion. For if its Water might be driven by the courſe of
Heaven towards the Weſt, it would have been dry many ages
ſince: Beſides that our Water runneth not onely towards the
Weſt, But returneth backwards towards the Eaſt, and that in
dinal Periods: And whereas you ſay by the example of Rivers,
that though the courſe of the Sea were Originally that onely
1from Eaſt to Weſt, yet nevertheleſs the different Poſition of the
Shores may make part of the Water regurgitate, and return
backwards: I grant it you, but it is neceſſary that you take
tice my Simplicius, that where the Water upon that account
returneth backwards, it doth ſo there perpetually; and where
it runneth ſtraight forwards, it runneth there alwayes in the ſame
manner; for ſo the example of the Rivers ſhewes you: But in the
caſe of the ebbing and flowing, you muſt finde and give us ſome
reaſon why it doth in the ſelf ſame place run one while one way,
and another while another; Effects that being contrary & irregular,
can never be deduced from any uniform and conſtant Cauſe:
And this Argument, that overthrows the Hypotheſis of the
tion contributed to the Sea from the Heavens diurnal motion,
doth alſo confute that Poſition of thoſe who would admit the ſole
diurnal motion of the Earth, and believe that they are able with
that alone to give a reaſon of the Flux and Reflux: Of which
effect ſince it is irregular, the cauſe muſt of neceſſity be irregular
and alterable.
A reaſon of the
continual motion of
the Air and
ter may be given,
making the Earth
moveable, then by
making it
able.
Its improbable that
the element of Fire
ſhould be carried
round by the
cave of the Moon.
+ A Treatiſe of our
Author formerly
cited.
The Ebbing and
Flowing cannot
pend on the motion
of Heaven.
SIMP. I have nothing to reply, neither of my own, by reaſon
of the weakneſs of my underſtanding; nor of that of others, for
that the Opinion is ſo new: But I could believe that if it were
ſpread amongſt the Schools, there would not want Phyloſophers
able to oppoſe it.
SAGR. Expect ſuch an occaſion; and we in the mean time
if it ſeem good to Salviatus, will proceed forward.
SALV. All that which hath been ſaid hitherto, pertaineth to
the diurnal period of the ebbing and flowing; of which we have in
the firſt place demonſtrated in general the primary and univerſal
Cauſe, without which, no ſuch effect would follow: Afterw ds
paſſing to the particular Accidents, various, and in a certain ſort
irregular, that are obſerved therein: We have handled the
dary and concommitant Cauſes upon which they depend. Now
follow the two other Periods, Monethly, and Annual, which do
not bring with them new and different Accidents, other than
thoſe already conſidered in the diurnal Period; but they
rate on the ſame Accidents, by rendring them greater and leſſer
in ſeveral parts of the Lunar Moneth, and in ſeveral times of
the Solar Year; as if that the Moon and Sun did each conceive
it ſelf apart in operating and producing of thoſe Effects; a thing
that totally claſheth with my underſtanding, which ſeeing how
that this of Seas is a local and ſenſible motion, made in an
menſe maſs of Water, it cannot be brought to ſubſcribe to
Lights, to temperate Heats, to predominacies by occult
ties, and to ſuch like vain Imaginations, that are ſo far from
ing, or being poſſible to be Cauſes of the Tide; that on the
1trary, the Tide is the cauſe of them, that is, of bringing them
into the brains more apt for loquacity and oſtentation, than for
the ſpeculation and diſcovering of the more abſtruſe ſecrets of
Nature; which kind of people, before they can be brought to
prononnce that wiſe, ingenious, and modeſt ſentence, I know it
not, ſuffer to eſcape from their mouths and pens all manner of
travagancies. And the onely obſerving, that the ſame Moon, and
the ſame Sun operate not with their light with their motion, with
great heat, or with temperate, on the leſſer reeeptaces of Water,
but that to effect their flowing by heat, they muſt be reduced to
little leſſe than boiling, and in ſhort, we not being able artificially
to imitate any way the motions of the Tide, ſave only by the
tion of the Veſſel, ought it not to ſatisfie every one, that all
the other things alledged, as cauſes of thoſe eſſects, are
vaine fancies, and altogether eſtranged from the Truth. I

ſay, therefore, that if it be true, that of one effect there is but
one ſole primary cauſe, and that between the cauſe and effect,
there is a firm and conſtant connection; it is neceſſary that
ſoever there is ſeen a firm and conſtant alteration in the effect,
there be a firm and conſtant alteration in the cauſe. And
cauſe the alterations that happen in the ebbing and flowing in
ſeveral parts of the Year and Moneths, have their periods firm and
conſtant, it is neceſſary to ſay, that a regular alteration in thoſe
ſame times happeneth in the primary cauſe of the ebbings and
flowings. And as for the alteration that in thoſe times happens

in the ebbings and flowings conſiſteth onely in their greatneſs;
that is, in the Waters riſing and falling more or leſſe, and in
running with greater or leſſe impetus; therefore it is neceſſary,
that that which is the primary cauſe of the ebbing and flowing,
doth in thoſe ſame determinate times increaſe and diminiſh its
force. But we have already concluded upon the inequality and
irregularity of the motion of the Veſſels containing the Water to
be the primary cauſe of the ebbings and flowings. Therefore
it is neceſſary, that that irregularity, from time to time,
ſpondently grow more irregular, that is, grow greater and leſſer.
Now it is requiſite, that we call to minde, that the irregularity,
that is, the different velocity of the motions of the Veſſels, to
wit, of the parts of the Terreſtrial Superficies, dependeth on
their moving with a compound motion, reſulting from the
mixtion of the two motions, Annual and Diurnal, proper to the
whole Terreſtrial Globe; of which the Diurnal converſion, by
one while adding to, and another while ſubſtracting from, the
Annual motion, is that which produceth the irregularity in the
compound motion; ſo that, in the additions and ſubſtractions,
that the Diurnal revolution maketh from the Annual motion,
1conſiſteth the original cauſe of the irregular motion of the
ſels, and conſequently of the Ebbing and Flowing: inſomuch

that if theſe additions and ſubſtractions ſhould alwayes proceed
in the ſame proportion, in reſpect of the Annual motion, the
cauſe of the Ebbing and Flowing would indeed continue, but
yet ſo as that they would perpetually return in the ſelf ſame
ner: But we are to finde out the cauſe of making the ſame
bings and Flowings in divers times greater and leſſer:
fore we muſt (if we will retain the identity of the cauſe) find the
alteration in theſe additions and ſubſtractions, that make them
more & leſs potent, in producing thoſe effects which depend
upon. But I ſee not how that potency and impotence can be
duced, unleſſe by making the ſame additions and ſubſtractions,
one while greater, and another while leſſer; ſo that the
tion and the retardment of the compound motion, may be made,
ſometimes in greater, and ſometimes in leſſer proportion.
The alterations
in the effects argue
alteration in the
cauſe.
The cauſes at
large aſſigned of
the Periods
nethly and
al of the ebbing
and flowing.
The monethly
and annual
tions of the tide can
depend upon
thing, ſave on the
alteration of the
additions &
ſtractions of the
diurnal period from
the annual.
SAGR. I feel my ſelf very gently led, as it were, by the hand,
and though I finde no rubs in the way, yet nevertheleſſe, like a
blind man, I ſee not whether your Clue leadeth me, nor can I
imagine where ſuch a Journey will end.
SALV. Though there be a great difference between my ſlow
pac't Philoſophy, and your more nimble Reaſon, yet
leſſe, in this particular which we are now upon, I do not much
wonder, if the apprehenſiveneſſe of your wit be a little
red by the dark and thick miſt that hides the mark, at which we
aime: and that which leſſeneth my admiration is, the
brance of the many hours, many dayes, yea more, many nights
that I have conſumed in this contemplation, and of the many
times that, deſpairing to bring it to a period, I have, for an
couragement of my ſelf, indeavoured to believe, by the
ple of the unfortunate Orlando, that that might not poſſibly be
true, which yet the teſtimony of ſo many credible men ſet
fore my eyes: wonder not, therefore, if this once, contrary to
your cuſtome, you do not foreſee what I intend: and if you will
needs admire, I believe that the event, as far as I can judge
expected, will make you ceaſe your wonderment.
SAGR. I thank God, that he did not permit that deſperation
of yours to end in the Exit that is fabled of the miſerable
lando, nor in that which haply is no leſſe fabulouſly related of
Ariſtotle,, that ſo neither my ſelf nor others ſhould be deprived
of the diſcovery of a thing, as abſtruſe as it was deſirable: I
beſeech you, therefore, to ſatisfie my eager appetite as ſoon as
you can.
SALV. I am ready to ſerve you: We were upon an inquiry
in what manner the additions and ſubſtractions of the
1all converſion from the Annual motion, could be made, one
while in a greater, and another while in a leſſer proportion;
which diverſity, and no other thing, could be aſſigned for the
cauſe of the alterations, Monethly and Annual, that are ſeen in
the greatneſſe of the Ebbings and Flowings. I will now
ſider how this proportion of the additions and ſubſtractions of

the Diurnal Revolution, and Annual motion may grow greater
and leſſer three ſeveral wayes. One is by increaſing and
niſhing the velocity of the Annual motion, retaining the
ons and ſubſtractions made by the Diurnal converſion in the
ſame greatneſſe, becauſe the Annual motion being about three
times greater, that is, more velocious than the Diurnal motion
(conſidered likewiſe in the Grand Circle) if we increaſe it
anew, the additions and ſubſtractions of the Diurnal motion
will occaſion leſſe alteration therein: but, on the other ſide,
making it more ſlow, it will be altered in greater proportion, by
that ſame diurnal motion, juſt as the adding or ſubſtracting
four degrees of velocity from one that moveth with twenty
grees, altereth his courſe leſſe, than thoſe very four degrees would
do, added or ſubſtracted from one that ſhould move onely with
ten degrees. The ſecond way would be, by making the
ons and ſubſtractions greater and leſſer, retaining the annual
tion in the ſame velocity; which is as eaſie to be underſtood, as it
is manifeſt, that a velocity v. gr. of 20. degr. is more altered by the
addition or ſubſtraction of 10. deg. than by the addition or
ction of 4. The third way would be, in caſe theſe two were joyned
together, diminiſhing the annual motion, & increaſing the diurnal
additions and ſubſtractions. Hitherto, as you ſee, it was no
hard matter to attain, but yet it proved to me very hard to find
by what means this might be effected in Nature. Yet in the end,

I finde that ſhe doth admirably make uſe thereof, and in wayes
almoſt incredible: I mean, admirable and incredible to us, but
not to her, who worketh even thoſe very things, which, to our
capacity, are of infinite wonder, with extraordinary facility and
ſimplicity: and that which it is hard for us to underſtand, is
ſie for her to effect. Now to proceed, having ſhewn that the
proportion between the additions and ſubſtractions of the
nal converſion and Annual motion may be made greater and
ſer, two wayes, (and I ſay two, becauſe the third is comprized in
the two firſt) I adde, that Nature maketh uſe of them both:
and farthermore, I ſubjoyn, that if ſhe did make uſe but of one
alone, it would be neceſſary to take away one of the two
dical alterations. That of the Monethly Period would ceaſe, if

the annual motion ſhould not alter. And in caſe the additions
and ſubſtractions of the diurnal revolution ſhould continually
1be equal, the alterations of the annual Period would fail.
Three wayes of
altering the
portion of the
ditions of the
nal Revolution to
the annual motion.
That which
us is hard to be
derſtood, is with
Nature eaſie to be
effected.
If the Diurnal
motion ſhould not
alter, the annual
Period would ceaſe
SAGR. It ſeems then, that the Monethly alteration of
bings and flowings dependeth on the alteration of the annual
motion of the Earth? And the annual alteration of thoſe
bings and flowings do, it ſeems, depend on the additions and
ſubſtractions of the diurnal converſion? And here now I finde
my ſelf worſe puzzled than before, and more out of hope of
being able to comprehend how this intricacy may be, which is
more inextricable, in my judgment, than the Gordian knot. And
I envy Simplicius, from whoſe ſilence I argue that he doth
prehend the whole buſineſſe, and is acquit of that confuſion
which greatly puzzleth my brains.
SIMP. I believe verily, Sagredus, that you are put to a
a ſtand; and I believe that I know alſo the cauſe of your
fuſion, which, if I miſtake not, riſeth from your underſtanding
part of thoſe particulars but even now alledged by Salviatus,
and but a part. It is true likewiſe that I find my ſelf free from the
like confuſion; but not for that cauſe as you think, to wit,
cauſe I apprehend the whole, nay it happens upon the quite
contrary account; namely, from my not comprehending any
thing; and confuſion is in the plurality of things, and not in
nothing.
SAGR. You ſee Salviatus, how a few checks given to
cius in the dayes preceding, have rendered him gentle, and
brought him from the capriol to the amble. But I beſeech you
without farther delay, put us both out of ſuſpence.
SALV. I will endeavour it to the utmoſt of my harſh way of
expreſſing my ſelf, the obtuſeneſſe of which, the acuteneſſe of
your wit ſhall ſupply. The accidents of which we are to enquire
the cauſes are two: The firſt reſpecteth the varieties that happen
in the ebbings and flowings in the Monethly Period; and the
thr relateth to the Annual. We will firſt ſpeak of the
ly, and then treat of the Annual; and it is convenient that we
reſolve them all according to the Fundamentals and Hypotheſis
already laid down, without introducing any novelty either in
ſtronomy, or in the Univerſe, in favour of the ebbings and
ings; therefore let us demonſtrate that of all the ſeveral
dents in them obſerved, the cauſes reſide in the things already

known, and received for true and undoubted. I ſay therefore,
that it is a truly natural, yea neceſſary thing, that one and the ſame
moveable made to move round by the ſame moving virtue in a
longer time, do make its courſe by a greater circle, rather than
by a leſſer; and this is a truth received by all, and
firmed by all experiments, of which we will produce a few.

In the wheel-clocks, and particularly in the great ones, to
1derate the time, the Artificers that make them accomodate a
tain voluble ſtaffe horozontally, and at each end of it they
ſten two Weights of Lead, and when the time goeth too ſlow,
by the onely removing thoſe Leads a little nearer to the centre
of the ſtaffe, they render its vibrations more frequent; and on
the contrary to retard it, it is but drawing thoſe Weights more
towards the ends; for ſo the vibrations are made more ſeldome,
and conſequently the intervals of the hours are prolonged.
The true
theſis may diſpatch
its revolutions in a
ſhorter time, in
leſſer circles than
in greater; the
which is proved by
two examples.
The firſt
ample.
Here the movent vertue is the ſame, namely the counterpoiſe,

the moveables are thoſe ſame Weights of lead, and their
brations are more frequent when they are neerer to the centre,
that is, when they move by leſſer circles. Hanging equal
Weights at unequal cords, and being removed from their
pendicularity, letting them go; we ſhall ſee thoſe that are
dent at the ſhorter cords, to make their vibrations under ſhorter
times, as thoſe that move by leſſer circles. Again, let ſuch a
kind of Weight be faſtened to a cord, which cord let play upon
a ſtaple faſtened in the Seeling, and do you hold the other end
of the cord in your hand, and having given the motion to the
pendent Weight, whilſt it is making its vibrations, pull the
end of the cord that you hold in your hand, ſo that the Weight
may riſe higher and higher: In its riſing you ſhall ſee the
quency of its vibrations encreaſe, in regard that they are made
ſucceſſively by leſſer and leſſer circies. And here I deſire you to

take notice of two particulars worthy to be obſerved. One is
that the vibrations of one of thoſe plummets are made with ſuch
a neceſſity under ſuch determinate times, that it is altogether
impoſſible to cauſe them to be made under other times, unleſſe
it be by prolonging, or abreviating the cord; of which you
may alſo at this very inſtant aſcertain your ſelves by experience,
tying a ſtone to a pack-threed, and holding the other end in
your hand, trying whether you can ever by any artifice be able
to ſwing it this way and that way in other than one determinate
time, unleſſe by lengthening or ſhortening the ſtring, which
you will find to be abſolutely impoſſible. The other particular
truly admirable is, that the ſelf ſame pendulum makes its
tions with one and the ſame frequency, or very little, and as it
were inſenſibly different, whether they be made by very great,
or very ſmall arches of the ſelf-ſame circumference. I mean that
whether we remove the pendulum from perpendicularity one, two,
or three degrees onely, or whether we remove it 70. 80. nay to
an entire quadrant, it being let go, will in the one caſe and in
the other make its vibrations with the ſame frequency, as well
the former where it is to move by an arch of but four or ſix
grees, as the ſecond, where it is to paſſe arches of 160. or more
1degrees. Which may the better be ſeen, by hanging two weights
at two ſtrings of equal length, and then removing them from
pendicularity, one a little way, and the other very far; the which
being ſet at liberty, will go & return under the ſame times, the one
by arches very ſmall, & the other by very great ones, from whence
followeth the concluſion of an admirable Problem; which is,

That a Quadrant of a Circle being given (take a little diagram of
the ſame, [in Fig. 3.]) as for inſtance: A B erect to the Hori­
zon, ſo as that it reſt upon the plain touching in the point B. and
an Arch being made with a Hoop well plained and ſmoothed in
the concave part, bending it according to the curvity of the
cumference A D B. So that a Bullet very round and ſmooth
may freely run to and again within it (the rim of a Sieve is very
proper for the experiment) I ſay, that the Bullet being put in any
what ever place, neer or far from the loweſt term B. As for
ſtance, putting it in the point C, or here in D, or in E; and then
let go, it will in equal times, or inſenſibly different arrive at the
term B, departing from C, or from D, or from E, or from
ever other place; an accident truly wonderfull. We may add
another accident no leſs ſtrange than this, which is, That
over by all the cords drawn from the point B to the points C,
D, E; and to any other whatſoever, taken not onely in the
drant B A, but in all the whole circumference of the Circle the
ſaid moveable ſhall deſcend in times abſolutely equal; inſomuch
that it ſhall be no longer in deſcending by the whole Diameter
erect perpendicularly upon the point B, then it ſhall in
ing by B. C. although it do ſublend but one ſole degree, or a
ſer Arch. Let us add the other wonder, which is, That the
tions of the falling bodies made by the Arches of the Quadrant
A B; are made in ſhorter times than thoſe that are made by the
cords of thoſe ſame Arches; ſo that the ſwifteſt motion, and
made by a moveable in the ſhorteſt time, to arrive from the
point A, to the term B, ſhall be that which is made, not by the
right line A, B, (although it be the ſhorteſt of all thoſe that can
de drawn between the points A. B.) but by the circumference
A D B. And any point being taken in the ſaid Arch; as for
example: The point D. and two cords drawn A D, and D. B.
the moveable departing from the qoint A, ſhall in a leſs time
come to B, moving by the two cords A D and D B. than by the
ſole cord A, B. But the ſhorteſt of all the times ſhall be that of
the fall by the Arch A D B. And the ſelf ſame accidents are
to be underſtood of all the other leſſer Arches taken from the
lowermoſt term B. upwards.
The ſecond
ample.
Two particular
notable accidents
in the penduli and
their vibrations.
Admirable
blems of
bles deſcending by
the Quadrant of a
Circle, and of thoſe
deſcending by all
the cords of the
whole Circle.
SAGR. No more, no more; for you ſo confund and fill me
with Wonders, and diſtract my thoughts ſo many ſeveral wayes,
1that I fear I ſhall have but a ſmall part of it left free and
gaged, to apply to the principal matter that is treated of, and
which of it ſelf is but even too obſcure and intricate: So that
I intreat you to vouchſafe me, having once diſpatcht the buſineſs
of the ebbings and flowings, to do this honour to my houſe (and
yours) ſome other dayes, and to diſcourſe upon the ſo many other
Problems that we have left in ſuſpence; and which perhaps are
no leſs curious and admirable, than this that hath been diſcuſſed
theſe dayes paſt, and that now ought to draw to a
cluſion.
SALV. I ſhall be ready to ſerve you, but we muſt make more
than one or two Seſſions; if beſides the other queſtions reſerved
to be handled apart, we would diſcuſſe thoſe many that pertain
to the local motion, as well of natural moveables, as of the
ed: an Argument largely treated of by our Lyncean
mick. But turning to our firſt purpoſe, where we were about to
declare, That the bodies moving circularly by a movent virtue,
which continually remaineth the ſame, the times of the
tions were prefixt and determined, and impoſſible to be made
longer or ſhorter, having given examples, and produced
ments thereof, ſenſible, and feaſible, we may confirm the ſame
truth by the experiences of the Celeſtial motions of the Planets;
in which we ſee the ſame rule obſerved; for thoſe that move by
greater Circles, confirm longer times in paſſing them. A moſt
pertinent obſervation of this we have from the Medicæan
nets, which in ſhort times make their revolutions about Jupiter:
Inſomuch that it is not to be queſtioned, nay we may hold it for
ſure and certain, that if for example, the Moon continuing to be
moved by the ſame movent faculty, ſhould retire by little and
little in leſſer Circles, it would acquire a power of abreviating
the times of its Periods, according to that Pendulum, of which in
the courſe of its vibrations, we by degrees ſhortned the cord, that
is contracted the Semidiameter of the circumferences by it paſſed.
Know now that this that I have alledged an example of it in the
Moon, is ſeen and verified eſſentially in fact. Let us call to mind,
that it hath been already concluded by us, together with Coperni-

cus, That it is not poſſible to ſeparate the Moon from the Earth,
about which it without diſpute revolveth in a Moneth: Let us
remember alſo that the Terreſtrial Globe, accompanyed alwayes
by the Moon, goeth along the circumference of the Grand Orb
about the Sun in a year, in which time the Moon revolveth about
the Earth almoſt thirteen times; from which revolution it
eth, that the ſaid Moon ſometimes is found near the Sun; that is,
when it is between the Sun and the Earth, and ſometimes
much more remote, that is, when the Earth is ſituate between
1the Moon and Sun; neer, in a word, at the time of its conjun
ction and change; remote, in its Full and Oppoſition; and the
greateſt vicinity differ the quantity of the Diameter of the
nar Orb. Now if it be true that the virtue which moveth the
Earth and Moon, about the Sun, be alwayes maintained in
the ſame vigour; and if it be true that the ſame moveable
moved by the ſame virtue, but in circles unequal, do in ſhorter
times paſſe like arches of leſſer circles, it muſt needs be granted,
that the Moon when it is at a leſſe diſtance from the Sun, that is
in the time of conjunction, paſſeth greater arches of the Grand
Orb, than when it is at a greater diſtance, that is in its Opppſition
and Full. And this Lunar inequality muſt of neceſſity be imparted
to the Earth alſo; for if we ſhall ſuppoſe a right line produced from
the centre of the Sun by the centre of the Terreſtrial Globe, and
prolonged as far as the Orb of the Moon, this ſhall be the
diameter of the Grand Orb, in which the Earth, in caſe it were
alone, would move uniformly, but if in the ſame ſemidiameter we
ſhould place another body to be carried about, placing it one
while between the Earth and Sun, and another while beyond
the Earth, at a greater diſtance from the Sun, it is neceſſary,
that in this ſecond caſe the motion common to both, according
to the circumference of the great Orb by means of the diſtance
of the Moon, do prove a little ſlower than in the other caſe,
when the Moon is between the Earth and Sun, that is at a leſſer
diſtance. So that in this buſineſſe the very ſame happeneth that
befals in the time of the clock; that lead which is placed one
while farther ſrom the centre, to make the vibrations of the
ſtaffe or ballance leſſe frequent, and another while nearer, to
make them thicker, repreſenting the Moon. Hence it may be
manifeſt, that the annual motion of the Earth in the Grand
Orb, and under the Ecliptick, is not uniform, and that its
regularity proceedeth from the Moon, and hath its Monethly
Periods and Returns. And becauſe it hath been concluded, that
the Monethly and Annual Periodick alterations of the ebbings
and flowings, cannot be deduced from any other cauſe than
from the altered proportion between the annual motion and the
additions and ſubſtractions of the diurnal converſion; and that
thoſe alterations might be made two wayes, that is by altering
the annual motion, keeping the quantity of the additions
altered, or by changing of the bigneſſe of theſe, reteining the
uniformity of annual motion. We have already found the firſt
of theſe, depending on the irregularity of the annual motion
occaſioned by the Moon, and which hath its Monethly Periods.
It is therefore neceſſary, that upon that account the ebbings
and flowings have a Monethly Period in which they do grow
1greater and leſſer. Now you ſee that the cauſe of the Monethly
Period reſideth in the annual motion; and withal you ſee how
much the Moon is concerned in this buſineſs, and how it is
with interrupted apart, without having any thing to do with either,
with Seas or Waters.
The Earths
nual motion by the
Ecliptick, unequal
by means of the
Moons motion.
SAGR. If one that never had ſeen any kinde of Stairs or
der, were ſhewed a very high Tower, and asked if ever he hoped
to climb to the top of it, I verily believe that he would anſwer he
did not, not conceiving how one ſhould come thither any way
except by flying; but ſhewing him a ſtone of but a foot high, and
asking him whether he thought he could get to the top of that,
I am certain that he would anſwer he could; and farther, that he
would not deny, but that it was not onely one, but ten, twenty,
and an hundred times eaſier to climb that: But now if he ſhould
be ſhewed the Stairs, by means whereof, with the facility by him
granted, it is poſſible to get thither, whither he a little before had
affirmed it was impoſſible to aſcend, I do think that laughing at
himſelf he would confeſs his dulneſs of apprehenſion. Thus,
Salviatus, have you ſtep by ſtep ſo gently lead me, that, not
without wonder, I finde that I am got with ſmall pains to that
height which I deſpaired of arriving at. 'Tis true; that the
caſe having been dark, I did not perceive that I was got nearer
to, or arrived at the top, till that coming into the open Air I
covered a great Sea, and ſpacious Country: And as in aſcending
one ſtep, there is no labour; ſo each of your propoſitions by it
ſelf ſeemed to me ſo plain, that thinking I heard but little or
thing that was new unto me, I conceived that my benefit thereby
had been little or none at all: Whereupon I was the more
zed at the unexpected exit of this diſcourſe, that hath guided me
to the knowledge of a thing which I held impoſſible to be
monſtrated. One doubt onely remains, from which I deſire to
be freed, and this it is; Whether that if the motion of the Earth
together with that of the Moon under the Zodiack are irregular
motions, thoſe irregularities ought to have been obſerved and
ken notice of by Aſtronomers, which I do not know that they
are: Therefore I pray you, who are better acquainted with theſe
things than I, to free me from this doubt, and tell me how the
caſe ſtands.
SALV. You ask a rational queſtion, and anſwering to the

jection, I ſay; That although Aſtronomy in the courſes of many
ages hath made a great progreſs in diſcovering the conſtitution
and motions of the Celeſtial bodies, yet is it not hitherto arrived
at that height, but that very many things remain undecided, and
haply many others alſo undiſcovered. It is to be ſuppoſed that the
firſt obſervers of Heaven knew no more but one motion common
1to all the Stars, as is this diurnal one: yet I believe that in few
dayes they perceived that the Moon was inconſtant in keeping
company with the other Stars; but yet withal, that many years
paſt, before that they diſtinguiſhed all the Planets: And in
ticular, I conceit that Saturn by its ſlowneſs, and Mercury by

ſon of its ſeldom appearing, were the laſt that were obſerved to
be wandring and errant. It is to be thought that many more
years run out before the ſtations and retrogradations of the three
ſuperiour Planets were known, as alſo their approximations and
receſſions from the Earth, neceſſary occaſions of introducing the
Eccentrix and Epicicles, things unknown even to Ariſtotle, for
that he makes no mention thereof. Mercury, and Venus, with
their admirable apparitions; how long did they keep
mers in ſuſpence, before that they could reſolve (not to ſpeak of
any other of their qualities) upon their ſituation? Inſomuch
that the very order onely of the Mundane bodies, and the
gral ſtructure of the parts of the Univerſe by us known, hath been
doubted of untill the time of Copernicus, who hath at laſt given
us notice of the true conſtitution, and real ſyſteme, according to
which thoſe parts are diſpoſed; ſo that at length we are certain
that Mercury, Venus, and the other Planets do revolve about
the Sun; and that the Moon revolveth about the Earth. But

how each Planet governeth it ſelf in its particular revolution, and
how preciſely the ſtructure of its Orb is framed; which is that
which is vulgarly called the Theory of the Planets, we cannot as
yet undoubtedly reſolve. Mars, that hath ſo much puzled our
Modern Aſtronomers, is a proof of this: And to the Moon her
ſelf there have been aſſigned ſeveral Theories, after that the ſaid
Copernicus had much altered it from that of Ptolomy. And to
deſcend to our particular caſe, that is to ſay, to the apparent
tion of the Sun and Moon; touching the former, there hath been
obſerved a certain great irregularity, whereby it paſſeth the two

ſemicircles of the Ecliptick, divided by the points of the
noxes in very different times; in paſſing one of which, it
eth about nine dayes more than in paſſing the other; a difference,
as you ſee, very great and notable. But if in paſſing ſmall arches,
ſuch for example as are the twelve Signs, he maintain a moſt
gular motion, or elſe proceed with paces, one while a little more
ſwift, and another more ſlow, as it is neceſſary that it do, in caſe
the annual motion belong to the Sun onely in appearance, but
in reality to the Earth in company with the Moon, it is what hath
not hitherto been obſerved, nor it may be, ſought. Touching

the Moon in the next place, whoſe reſtitutions have been
cipally lookt into an account of the Eclipſes, for which it is
ficient to have an exact knowledge of its motion about the Earth,
1it hath not been likewiſe with a perfect curioſity inquired, what
its courſe is thorow the particular arches of the Zodiack. That
therefore the Earth and Moon in running through the Zodiack,
that is round the Grand Orb, do ſomewhat accellerate at the
Moons change, and retard at its full, ought not to be doubted;
for that the ſaid difference is not manifeſt, which cometh to be
unobſerved upon two accounts; Firſt, Becauſe it hath not been
lookt for. Secondly, Becauſe that its poſſible it may not be very
great. Nor is there any need that it ſhould be great, for the
ducing the effect that we ſee in the alteration of the greatneſs of
ebbings and flowings. For not onely thoſe alterations, but the

Tides themſelves are but ſmall matters in reſpect of the grandure
of the ſubjects on which they work; albeit that to us, and to our
littleneſs they ſeem great. For the addition or ſubduction of
one degree of velocity where there are naturally 700, or 1000,
can be called no great alteration, either in that which conferreth
it, or in that Which receiveth it: the Water of our Mediterrane
carried about by the diurnal revolution, maketh about 700 miles
an hour, (which is the motion common to the Earth and to it, and
therefore not perceptible to us) & that which we ſenſibly diſcern
to be made in the ſtreams or currents, is not at the rate of full one
mile an hour, (I ſpeak of the main Seas, and not of the Straights)
and this is that which altereth the firſt, naturall, and grand
tion; and this motion is very great in reſpect of us, and of Ships:
for a Veſſel that in a ſtanding Water by the help of Oares can
make v. g. three miles an hour, in that ſame current will row
twice as far with the ſtream as againſt it: A notable difference
in the motion of the Boat, though but very ſmall in the motion
of the Sea, which is altered but its ſeven hundredth part. The
like I ſay of its riſing, and falling one, two, or three feet; and
ſcarcely four or five in the utmoſt bounds of a ſtreight, two
ſand, or more miles long, and where there are depths of hundreds
of feet; this alteration is much leſs than if in one of the Boats
that bring us freſh Water, the ſaid Water upon the arreſt of the
Boat ſhould riſe at the Prow the thickneſs of a leaf. I conclude
therefore that very ſmall alterations in reſpect of the immenſe
greatneſs, and extraordinary velocity of the Seas, is ſufficient to
make therein great mutations in relation to our ſmallneſs, and to
our accidents.
Many things
may remain as yet
unobſerved in
ſtronomy.
Saturn for its
ſlowneſs, and
cury for its
neſs of appearing
were amongſt thoſe
that were laſt
ſerved.
Particular
ctures of the Orbs
of the Planets not
yet well reſolved.
The Sun
eth one half of the
Zodiack nine days
ſooner than the
other.
The Moons
tion principally
ſought in the
count of Eclipſes.
Ebbings and
flowings are petty
things in
ſon of the vaſtneſs
of Seas, and of the
velocity of the
tion of the
ſtrial Globe.
SAGR. I am fully ſatisfied as to this particular; it remains to
declare unto us how thoſe additions and ſubſtractions derived
from the diurnal Vertigo are made one while greater, and
ther while leſſer; from which alterations you hinted that the
nual period of the augmentations and diminutions of the
bings and flowings did depend.
1
SALV. I will uſe my utmoſt endeavours to render my ſelf

intelligible, but the difficulty of the accident it ſelf, and the
great attention of mind requiſite for the comprehending of it,
conſtrains me to be obſcure. The unequalities of the additions
and ſubſtractions, that the diurnal motion maketh to or from
the annual dependeth upon the inclination of the Axis of the
urnal motion upon the plane of the Grand Orb, or, if you pleaſe,
of the Ecliptick; by means of which inclination the Equinoctial
interſecteth the ſaid Ecliptick, remaining inclined and oblique
upon the ſame according to the ſaid inclination of Axis. And the
quantity of the additions importeth as much as the whole
ter of the ſaid Equinoctial, the Earths centre being at the ſame
time in the Solſtitial points; but being out of them it importeth
leſſe and leſſe, according as the ſaid centre ſucceſſively
cheth to the points of the Equinoxes, where thoſe additions are
leſſer than in any other places. This is the whole buſineſſe, but
wrapt up in the obſcurity that you ſee.
The cauſes of
the inequality of
the additions and
ſubſtractions of the
diurnal converſion
from the annual
motion.
SAGR. Rather in that which I do no not ſee; for hitherto I
comprehend nothing at all.
SALV. I have already foretold it. Nevertheleſſe we will try
whether by drawing a Diagram thereof, we can give ſome
ſmall light to the ſame; though indeed it might better be ſet
forth by ſolid bodies than by bare Schemes; yet we will help our
ſelves with Perſpective and fore-ſhortning. Let us draw
fore, as before, the circumference of the Grand Orb, [as in
Fig. 4.] in which the point A is underſtood to be one of the
Solſtitials, and the diameter A P the common Section of the
Solſtitial Colure, and of the plane of the Grand Orb or
tick; and in that ſame point A let us ſuppoſe the centre of the
Terreſtrial Globe to be placed, the Axis of which C A B,
clined upon the Plane of the Grand Orb, falleth on the plane of
the ſaid Colure that paſſeth thorow both the Axis of the
ctial, and of the Ecliptick. And for to prevent confuſion, let
us only draw the Equinoctial circle, marking it with theſe
cters D G E F, the common ſection of which, with the plane of
the grand Orb, let be the line D E, ſo that half of the ſaid
quinoctial D F E will remain inclined below the plane of the
Grand Orb, and the other half D G E elevated above. Let
now the Revolution of the ſaid Equinoctial be made, according
to the order of the points D G E F, and the motion of the
tre from A towards E. And becauſe the centre of the Earth
being in A, the Axis C B (which is erect upon the diameter of
the Equinoctial D E) falleth, as hath been ſaid, in the
tial Colure, the common Section of which and of the
Grand Orb, is the diameter P A, the ſaid line P A ſhall
1be perpendicular to the ſame D E, by reaſon that the Colure is
erect upon the grand Orb; and therefore the ſaid D E,
ſhall be the Tangent of the grand Orb in the point A.
So that in this Poſition the motion of the Centre by the arch
A E; that is, of one degree every day differeth very little; yea,
is as if it were made by the Tangent D A E. And becauſe by
means of the diurnal motion the point D, carried about by G,
unto E, encreaſeth the motion of the Centre moved almoſt in the
ſame line D E, as much as the whole diameter D E amounts
unto; and on the other ſide diminiſheth as much, moving about
the other ſemicircle E F D. The additions and ſubductions
in this place therefore, that is in the time of the ſolſtice, ſhall be
meaſured by the whole diameter D E.
Let us in the next place enquire, Whether they be of the ſame
bigneſs in the times of the Equinoxes; and tranſporting the
Centre of the Earth to the point I, diſtant a Quadrant of a
Circle from the point A. Let us ſuppoſe the ſaid Equinoctial
to be G E F D, its common ſection with the grand Orb D E, the
Axis with the ſame inclination C B; but the Tangent of the grand
Orb in the point I ſhall be no longer D E, but another which
ſhall cut that at right Angles; and let it be this marked H I L,
according to which the motion of the Centre I, ſhall make its
greſs, proceeding along the circumference of this grand Orb.
Now in this ſtate the Additions and Subſtractions are no longer
meaſured by the diameter D E, as before was done; becauſe that
diameter not diſtending it ſelf according to the line of the annual
motion H L, rather cutting it at right angles, thoſe terms D E, do
neither add nor ſubſtract any thing; but the Additions and
Subſtractons are to be taken from that diameter that falleth
in the plane that is errect upon the plane of the grand Orb, and
that interſects it according to the line H L; which diameter in this
caſe ſhall be this G F and the Adjective, if I may ſo ſay, ſhall
be that made by the point G, about the ſemicircle G E F, and the
Ablative ſhall be the reſt made by the other ſemicircle F D G.
Now this diameter, as not being in the ſame line H L of the
annual motion, but rather cutting it, as we ſee in the point I, the
term G being elevated above, and E depreſſed below the plane
of the grand Orb, doth not determine the Additions and
ſtractions according to its whole length, but the quantity of thoſe
firſt ought to be taken from the part of the line H L, that is
tercepted between the perpendiculars drawn upon it from the
terms G F; namely, theſe two G S, and F V: So that the
ſure of the additions is the line S V leſſer then G F, or then D E;
which was the meaſure of the additions in the Solſtice A. And
ſo ſucceſſively, according as the centre of the Earth ſhall be
1ſtituted in other points of the Quadrant A I, drawing the
gents in the ſaid points, and the perpndiculars upon the ſame
ling from the terms of the diameters of the Equinoctial drawn
from the errect planes by the ſaid Tangents to the plane of the
grand Orb; the parts of the ſaid Tangents (which ſhall
nually be leſſer towards the Equinoctials, and greater towards the
Solſtices) ſhall give us the quantities of the additions and
ctions. How much in the next place the leaſt additions differ from
the greateſt, is eaſie to be known, becauſe there is the ſame
ference betwixt them, as between the whole Axis or Diameter of
the Sphere, and the part thereof that lyeth between the
Circles; the which is leſs than the whole diameter by very near a
twelfth part, ſuppoſing yet that we ſpeak of the additions and
ſubſtractions made in the Equinoctial; but in the other
lels they are leſſer, according as their diameters do diminiſh.
This is all that I have to ſay upon this Argument, and all perhaps
that can fall under the comprehenſion of our knowledge, which,
as you well know, may not entertain any concluſions, ſave onely
thoſe that are firm and conſtant, ſuch as are the three kinds of
riods of the ebbings and flowings; for that they depend on cauſes
that are invariable, ſimple, and eternal. But becauſe that
condary and particular cauſes, able to make many alterations,
termix with theſe that are the primary and univerſal; and theſe
ſecondary cauſes being part of them inconſtant, and not to be
obſerved; as for example, The alteration of Winds, and part
(though terminate and fixed) unobſerved for their multiplicity,
as are the lengths of the Straights, their various inclinations
wards this or that part, the ſo many and ſo different depths of the
Waters, who ſhall be able, unleſs after very long obſervations, and
very certain relations, to frame ſo expeditious Hiſtories thereof, as
that they may ſerve for Hypoth eſes, and certain ſuppoſitions to
ſuch as will by their combinations give adequate reaſons of all the
appearances, and as I may ſay, Anomalie, and particular
rities that may be diſcovered in the motions of the Waters? I
will content my ſelf with advertiſing you, that the accidental
cauſes are in nature, and are able to produce many alterations;
for the more minute obſervations, I remit them to be made by
thoſe that frequent ſeveral Seas: and onely by way of a
ſion to this our conference, I will propoſe to be conſidered, how
that the preciſe times of the fluxes and refluxes do not onely
pen to be altered by the length of Straights, and by the
rence of depths; but I believe that a notable alteration may alſo
proceed from the comparing together of ſundry tarcts of Sea,
different in greatneſs; and in poſition, or, if you will,
tion; which difference happeneth exactly here in the Adriatick
1Gulph, leſſe by far than the reſt of the Mediterrane, and placed in
ſo different an inclination, that whereas that hath its bounds that
incloſeth it on the Eaſtern part, as are the Coaſts of Syria, this is
ſhut up in its more Weſterly part: and becauſe the ebbings and
flowings are much greater towards the extremities, yea, becauſe
the Seas riſings and fallings are there onely greateſt, it may
bably happen that the times of Flood at Venice may be the time of
low Water in the other Sea, which, as being much greater, and
diſtended more directly from Weſt to Eaſt, cometh in a certain
ſort to have dominion over the Adriatick: and therefore it
would be no wonder, in caſe the effects depending on the
mary cauſes, ſhould not hold true in the times that they ought,
and that correſpond to the periods in the Adriatick, as it doth
in the reſt of the Mediterrane. But theſe Particularities require
long Obſervations, which I neither have made as yet, nor ſhall I
ever be able to make the ſame for the future.
SAGR. You have, in my opinion, done enough in opening us
the way to ſo lofty a ſpeculation, of which, if you had given us
no more than that firſt general Propoſition that ſeemeth to me to
admit of no reply, where you declare very rationally, that the
Veſſels containing the Sea-waters continuing ſtedfaſt, it would
be impoſſible, according to the common courſe of Nature, that
thoſe motions ſhould follow in them which we ſee do follow;
and that, on the other ſide, granting the motions aſcribed, for
ther reſpects, by Copernicus to the Terreſtrial Globe, theſe ſame
alterations ought to enſue in the Seas, if I ſay you had told us no
more, this alone in my judgment, ſo far exceeds the vanities
troduced by ſo many others, that my meer looking on them
makes me nauſeate them, and I very much admire, that among
men of ſublime wit, of which nevertheleſs there are not a few,
not one hath ever conſidered the incompatibility that is between
the reciprocal motion of the Water contained, and the
lity of the Veſſel containing, which contradiction ſeemeth to me
now ſo manifeſt.
SALV. It is more to be admired, that it having come into the

thoughts of ſome to refer the cauſe of the Tide to the motion of
the Earth, therein ſhewing a more than common apprehenſion,
they ſhould, in afterwards driving home the motion cloſe with
no ſide; and all, becauſe they did not ſee that one ſimple and
uniform motion, as v. gr. the ſole diurnal motion of the
ſtrial Globe, doth not ſuffice, but that there is required an
ven motion, one while accelerated, and another while retarded:
for when the motion of the Veſſels are uniforme, the waters
contained will habituate themſelves thereto, without ever
king any alteration. To ſay alſo (as it is related of an ancient
1
Mathematician) that the motion of the Earth meeting with the
motion of the Lunar Orb, the concurrence of them occaſioneth
the Ebbing and Flowing, is an abſolute vanity, not onely
cauſe it is not expreſt, nor ſeen how it ſhould ſo happen, but the
falſity is obvious, for that the Revolution of the Earth is not
trary to the motion of the Moon, but is towards the ſame way.
So that all that hath been hitherto ſaid, and imagined by others,
is, in my judgment, altogether invalid. But amongſt all the
famous men that have philoſophated upon this admirable effect

of Nature, I more wonder at Kepler than any of the reſt, who
being of a free and piercing wit, and having the motion
bed to the Earth, before him, hath for all that given his ear and
aſſent to the Moons predominancy over the Water, and to
cult properties, and ſuch like trifles.
One ſingle
on of the
al Globe ſufficeth
not to produce the
Ebbing & Flowing
The opinion of
Seleucus the
thematician
red.
Kepler is with
veſpect blamed.
SAGR. I am of opinion, that to theſe more ſpaculative
ſons the ſame happened, that at preſent befalls me, namely, the
not underſtanding the intricate commixtion of the three Periods
Annual, Monethly, and Diurnal; And how their cauſes ſhould
ſeem to depend on the Sun, and on the Moon, without the Suns
or Moons having any thing to do with the Water; a buſineſſe,
for the full underſtanding of which I ſtand in need of a little
longer time to conſider thereof, which the novelty and difficulty
of it hath hitherto hindred me from doing: but I deſpair not, but
that when I return in my ſolitude and ſilence to ruminate that
which remaineth in my fancy, not very well digeſted, I ſhall
make it my own. We have now, from theſe four dayes
courſe, great atteſtations, in favour of the Copernican Syſteme,
amongſt which theſe three taken: the firſt, from the Stations and
Retrogradations of the Planets, and from their approaches, and
receſſions from the Earth; the ſecond, from the Suns revolving
in it ſelf, and from what is obſerved in its ſpots; the third, from
the Ebbing and Flowing of the Sea do ſhew very rational and
concluding.
SALV. To which alſo haply, in ſhort, one might adde a
fourth, and peradventure a fifth; a fourth, I ſay, taken from
the fixed ſtars, ſeeing that in them, upon exact obſervations, thoſe
minute mutations appear, that Copernicus thought to have been
inſenſible. There ſtarts up, at this inſtant, a fifth novelty, from
which one may argue mobility in the Terreſtrial Globe, by

means of that which the moſt Illuſtrious Signore Cæſare, of the
noble Family of the Marſilii of Bologna, and a Lyncean
demick, diſcovereth with much ingenuity, who in a very learned
Tract of his, ſheweth very particularly how that he had obſerved
a continual mutation, though very ſlow in the Meridian line,
of which Treatiſe, at length, with amazement, peruſed by me,
1I hope he will communicate Copies to all thoſe that are Students
of Natures Wonders.
Sig. Cæſare
ſilius obſerveth the
Meridian to be
moveable.
SAGR. This is not the firſt time that I have heard ſpeak of
the exquiſite Learning of this Gentleman, and of his ſhewing
himſelf a zealous Patron of all the Learned, and if this, or any
other of his Works ſhall come to appear in publique, we may be
aforehand aſſured, that they will be received, as things of great
value.
SALV. Now becauſe it is time to put an end to our
ſes, it remaineth, that I intreat you, that if, at more leaſure
ing over the things again that have been alledged you meet
with any doubts, or ſcruples not well reſolved, you will excuſe
my overſight, as well for the novelty of the Notion, as for the
weakneſſe of my wit, as alſo for the grandure of the Subject,
as alſo finally, becauſe I do not, nor have pretended to that
ſent from others, which I my ſelf do not give to this conceit,
which I could very eaſily grant to be a Chymæra, and a meer
paradox; and you Sagredus, although in the Diſcourſes paſt
you have many times, with great applauſe, declared, that you
were pleaſed with ſome of my conjectures, yet do I believe, that
that was in part more occaſioned by the novelty than by the
tainty of them, but much more by your courteſie, which did
think and deſire, by its aſſent, to procure me that content which
we naturally uſe to take in the approbation and applauſe of our
own matters: and as your civility hath obliged me to you; ſo
am I alſo pleaſed with the ingenuity of Simplicius. Nay, his
conſtancy in maintaining the Doctrine of his Maſter, with ſo
much ſtrength & undauntedneſs, hath made me much to love him.
And as I am to give you thanks, Sagredus, for your courteous
fection; ſo of Simplicius, I ask pardon, if I have ſometimes
moved him with my too bold and reſolute ſpeaking: and let him
be aſſured that I have not done the ſame out of any inducement
of ſiniſter affection, but onely to give him occaſion to ſet before
us more lofty fancies that might make me the more knowing.
SIMP. There is no reaſon why you ſhould make all theſe
cuſes, that are needleſſe, and eſpecially to me, that being
ſtomed to be at Conferences and publique Diſputes, have an
hundred times ſeen the Diſputants not onely to grow hot and
gry at one another, but likewiſe to break forth into injurious
words, and ſometimes to come very neer to blows. As for the
paſt Diſcourſes, and particulatly in this laſt, of the reaſon of
the Ebbing and Flowing of the Sea, I do not, to ſpeak the truth,
very well apprehend the ſame, but by that ſlight Idea, what
ver it be, that I have formed thereof to my ſelf, I confeſſe that
your conceit ſeemeth to me far more ingenuous than any of all
1thoſe that I ever heard beſides, but yet nevertheleſſe I eſteem it
not true and concluding: but keeping alwayes before the eyes
of my mind a ſolid Doctrine that I have learn't from a moſt
learned and ingenuous perſon, and with which it is neceſſary to
ſit down; I know that both you being asked, Whether God, by
his infinite Power and Wiſdome might confer upon the Element
of Water the reciprocal motion which we obſerve in the ſame in
any other way, than by making the containing Veſſel to move; I
know, I ſay, that you will anſwer, that he might, and knew how
to have done the ſame many wayes, and thoſe unimaginable to
our ſhallow underſtanding: upon which I forthwith conclude,
that this being granted, it would be an extravagant boldneſſe
for any one to goe about to limit and confine the Divine
Power and Wiſdome to ſome one particular conjecture of
his own.
SALV. This of yours is admirable, and truly Angelical
ctrine, to which very exactly that other accords, in like manner
divine, which whilſt it giveth us leave to diſpute, touching the
conſtitution of the World, addeth withall (perhaps to the end,
that the exerciſe of the minds of men might neither be
raged, nor made bold) that we cannot find out the works made
by his hands. Let therefore the Diſquiſition permitted and
dain'd us by God, aſſiſt us in the knowing, and ſo much more
admiring his greatneſſe, by how much leſſe we finde our ſelves
too dull to penetrate the profound Abyſſes of his infinite
dome.
SAGR. And this may ſerve for a final cloſe of our four dayes
Diſputations, after which, if it ſeem good to Salviatus, to take
ſome time to reſt himſelf, our curioſity muſt, of neceſſity, grant
him the ſame, yet upon condition, that when it is leſſe
dious for him, he will return and ſatisfie my deſire in particular
concerning the Problemes that remain to be diſcuſt, and that I
have ſet down to be propounded at one or two other
ces, according to our agreement: and above all, I ſhall very
impatiently wait to hear the Elements of the new Science of our
Academick about the natural and violent local Motions. And
in the mean time, we may, according to our cuſtome, ſpend an
hour in taking the Air in the Gondola that waiteth for us.
FINIS.
130[Figure 30]31[Figure 31]32[Figure 32]33[Figure 33]
Place this Plate
at the end of
the fourth
Dialogue