SALV. And have you no other conceit thereof than this?

SIMPL. This I think to be the proper definition of equal mo­tions.

Velocities are &longs;aid to be equal, when the &longs;paces pa&longs;&longs;ed are proportionate to their time.

SAGR. We will add moreover this other: and call that equal velocity, when the &longs;paces pa&longs;&longs;ed have the &longs;ame proportion, as the times wherein they are pa&longs;t, and it is a more univer&longs;al definition.

SALV. It is &longs;o: for it comprehendeth the equal &longs;paces pa&longs;t in equal times, and al&longs;o the unequal pa&longs;t in times unequal, but pro­portionate to tho&longs;e &longs;paces. Take now the &longs;ame Figure, and apply­ing the conceipt that you had of the more ha&longs;tie motion, tell me why you think the velocity of the Cadent by C B, is greater than the velocity of the De&longs;cendent by C A?

SIMPL. I think &longs;o; becau&longs;e in the &longs;ame time that the Cadent &longs;hall pa&longs;s all C B, the De&longs;cendent &longs;hall pa&longs;s in C A, a part le&longs;s than C B.

SALV. True; and thus it is proved, that the moveable moves more &longs;wiftly by the perpendicular, than by the inclination. Now con&longs;ider, if in this &longs;ame Figure one may any way evince the o­ther conceipt, and finde that the moveables were equally &longs;wift by both the lines C A and C B.

SIMPL. I &longs;ee no &longs;uch thing; nay rather it &longs;eems to contradict what was &longs;aid before.

SALV. And what &longs;ay you, Sagredus? I would not teach you what you knew before, and that of which but ju&longs;t now you pro­duced me the definition.

SAGR. The definition I gave you, was, that moveables may be called equally &longs;wift, when the &longs;paces pa&longs;&longs;ed are proportional to the times in which they pa&longs;&longs;ed; therefore to apply the defini­tion to the pre&longs;ent ca&longs;e, it will be requi&longs;ite, that the time of de­&longs;cent by C A, to the time of falling by C B, &longs;hould have the &longs;ame proportion that the line C A hath to the line C B; but I under&longs;tand not how that can be, for that the motion by C B is &longs;wifter than by C A.

SALV. And yet you mu&longs;t of nece&longs;&longs;ity know it. Tell me a little, do not the&longs;e 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 not­with&longs;tanding &longs;uch in compari&longs;on of that of the inclined, that two equal parts being taken in any place of the &longs;aid perpendicu­lar and inclining lines, the motion in the parts of the perpendicu­lar is alwaies more &longs;wift, than in the part of the inclination?

SAGR. I &longs;ay not &longs;o: but I could take a &longs;pace in the inclinati­on, in which the velocity &longs;hall be far greater than in the like &longs;pace taken in the perpendicular; and this &longs;hall be, if the &longs;pace in the perpendicular &longs;hould be taken near to the end C, and in the in­clination, far from it.

SALV. You &longs;ee then, that the Propo&longs;ition which &longs;aith, that the motion by the perpendicular is more &longs;wift than by the incli­nation, holds not true univer&longs;ally, but onely of the motions, which begin from the extremity, namely from the point of re&longs;t: without which re&longs;triction, the Propo&longs;ition would be &longs;o deficient, that its very direct contrary might be true; namely, that the mo­tion in the inclining plane is &longs;wifter than in the perpendicular: for it is certain, that in the &longs;aid inclination, we may take a &longs;pace pa&longs;t by the moveable in le&longs;s time, than the like &longs;pace pa&longs;t in the perpendicular. Now becau&longs;e the motion in the inclination is in &longs;ome places more, in &longs;ome le&longs;s, than in the perpendicular; there­fore in &longs;ome places of the inclination, the time of motion of the moveable, &longs;hall have a greater proportion to the time of the motion of the moveable, by &longs;ome places of the perpendicular, than the &longs;pace pa&longs;&longs;ed, to the &longs;pace pa&longs;&longs;ed: and in other places, the pro­portion of the time to the time, &longs;hall be le&longs;s than that of the &longs;pace to the &longs;pace. As for example: two moveables departing from their quie&longs;cence, namely, from the point C, one by the per­pendicular C B, [in Fig. 4.] and the other by the inclination C A, in the time that, in the perpendicular, the moveable &longs;hall have pa&longs;t all C B, the other &longs;hall have pa&longs;t C T le&longs;&longs;er. And therefore the time by C T, to the time by C B (which is equal) &longs;hall have a greater proportion than the line C T to C B, being that the &longs;ame to the le&longs;s, hath a greater proportion than to the greater.And on the contrary, if in C A, prolonged as much as is requi­&longs;ite, one &longs;hould take a part equal to C B, but pa&longs;t in a &longs;horter time; the time in the inclination &longs;hall have a le&longs;s proportion to the time in the perpendicular, than the &longs;pace to the &longs;pace. If therefore in the inclination and perpendicular, we may &longs;uppo&longs;e &longs;uch &longs;paces and velocities, that the proportion between the &longs;aid &longs;paces be greater and le&longs;s than the proportion of the times; we may ea&longs;ily grant, that there are al&longs;o &longs;paces, by which the times of the motions retain the &longs;ame proportion as the &longs;paces.

SAGR. I am already freed from my greate&longs;t doubt, and con­ceive that to be not onely po&longs;&longs;ible, but nece&longs;&longs;ary, which I but now thought a contradiction: but neverthele&longs;s I under&longs;tand not as yet, that this whereof we now are &longs;peaking, is one of the&longs;e po&longs;&longs;ible or nece&longs;&longs;ary ca&longs;es; &longs;o as that it &longs;hould be true, that the time of de&longs;cent by C A, to the time of the fall by C B, hath the &longs;ame proportion that the line C A hath to C B; whence it may without contradiction be affirmed, that the velocity by the incli­nation C A, and by the perpendicular C B, are equal.

SALV. Content your &longs;elf for this time, that I have removed your incredulity; but for the knowledge of this, expect it at &longs;ome other time, namely, when you &longs;hall &longs;ee the matters concer­ning local motion demon&longs;trated by our Academick; at which time you &longs;hall find it proved, that in the time that the one movea­ble falls all the &longs;pace C B, the other de&longs;cendeth by C A as far as the point T, in which falls the perpendicular drawn from the point B: and to find where the &longs;ame Cadent by the perpendi­cular 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 &longs;hall be the point &longs;ought. Whereby you &longs;ee how it is true, that the motion by C B is &longs;wifter than by the inclination C A (&longs;uppo&longs;ing the term C for the beginning of the motions compared) becau&longs;e the line C B is greater than C T, and the other from C unto the inter&longs;ection of the perpendicular drawn from A, unto the line C A, is greater than C A, and therefore the motion by it is &longs;wifter than by C A But when we compare the motion made by all C A, not with all the motion made in the &longs;ame time by the perpendicular continued, but with that made in part of the time, by the &longs;ole part C B, it hinders not, that the motion by C A, continuing to de&longs;cend beyond, may arrive to A in &longs;uch 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 fir&longs;t purpo&longs;e; which was to &longs;hew, that the grave moveable leaving its quie&longs;cence, pa&longs;&longs;eth defcending by all the degrees of tardity, precedent to any what&longs;oever degree of velocity that it aequireth, re-a&longs;&longs;uming the &longs;ame Figure which we u&longs;ed before, let us remem­ber that we did agree, that the De&longs;cendent 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 &longs;uppo&longs;e you will not &longs;cruple to grant, that upon ano­ther plane le&longs;s &longs;teep than A C; as for example, A D [in Fig. 5.] the motion of the de&longs;cendent would be yet more &longs;low than in the plane A C. So that it is not any whit dubitable, but that there may be planes &longs;o little elevated above the Horizon A B, that the moveable, namely the &longs;ame ball, in any the longe&longs;t time may reach the point A, which being to move by the plane A B, an infi­nite time would not &longs;uffice: and the motion is made always more &longs;lowly, by how much the declination is le&longs;s. It mu&longs;t be therefore confe&longs;t, that there may be a point taken upon the term B, &longs;o near to the &longs;aid B, that drawing from thence to the point A a plane, the ball would not pa&longs;s it in a whole year. It is requi&longs;ite next for you to know, that the impetus, namely the degree of velo­city the ball is found to have acquired when it arriveth at the point A, is &longs;uch, that &longs;hould it continue to move with this &longs;elf-&longs;ame degree uniformly, that is to &longs;ay, without accelerating or retarding; in as much more time as it was in coming by the inclining plane, it would pa&longs;s double the &longs;pace of the plane inclined: namely (for example) if the ball had pa&longs;t the plane D A in an hour, con­tinuing to move uniformly with that degree of velocity which it is found to have in its arriving at the term A, it &longs;hall pa&longs;s in an hour a &longs;pace double the length D A; and becau&longs;e (as we have &longs;aid) the degrees of velocity acquired in the points B and A, by the moveables that depart from any point taken in the perpendicu­lar C B, and that de&longs;cend, the one by the inclined plane, the o­ther by the &longs;aid perpendicular, are always equal: therefore the cadent by the perpendicular may depart from a term &longs;o near to B, that the degree of velocity acquired in B, would not &longs;uffice (&longs;till maintaining the &longs;ame) to conduct the moveable by a &longs;pace dou­ble 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 cour&longs;e of nature a moveable, all external and accidental impediments removed, moves upon an in­clining plane with greater and greater tardity, according as the inclination &longs;hall be le&longs;s; &longs;o 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 likewi&longs;e, that the de­gree of velocity acquired in &longs;ome point of the inclined plane, is equal to that degree of velocity which is found to be in the move­able that de&longs;cends by the perpendicular, in the point cut by a parallel to the Horizon, which pa&longs;&longs;eth by that point of the incli­ning plane; it mu&longs;t of nece&longs;&longs;ity be granted, that the cadent de­parting from re&longs;t, pa&longs;&longs;eth thorow all the infinite degrees of tar­dity, and that con&longs;equently, to acquire a determinate degree of velocity, it is nece&longs;&longs;ary that it move fir&longs;t by right lines, de&longs;cend­ing by a &longs;hort or long &longs;pace, according as the velocity to be acqui­red, ought to be either le&longs;s or greater, and according as the plane on which it de&longs;cendeth is more or le&longs;s inclined; &longs;o that a plane may be given with &longs;o &longs;mall inclination, that to acquire in it the a&longs;&longs;igned degree of velocity, it mu&longs;t fir&longs;t move in a very great &longs;pace, and take a very long time; whereupon in the horizontal plane, any how little &longs;oever velocity, would never be naturally acquired, &longs;ince that the moveable in this ca&longs;e will never move: but the

motion by the horizontal line, which is neither declined or incli­ned, is a circular motion about the centre: therefore the circu­lar 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 di&longs;cour&longs;es evince and demon&longs;trate the &longs;ame truth, but I will not by &longs;o great a digre&longs;­fion interrupt our principal argument: but rather will return to it upon &longs;ome other occa&longs;ion; e&longs;pecially &longs;ince we now a&longs;&longs;umed the &longs;ame, not to &longs;erve for a nece&longs;&longs;ary demon&longs;tration, but to adorn a Platonick Conceit; to which I will add another particular ob&longs;er­vation of our Academick, which hath in it &longs;omething of admira­ble. Let us &longs;uppo&longs;e among&longs;t the decrees of the divine Architect,a purpo&longs;e of creating in the World the&longs;e Globes, which we be­hold continually moving round, and of a&longs;&longs;igning the centre of their conver&longs;ions; and that in it he had placed the Sun immoveable, and had afterwards made all the &longs;aid Globes in the &longs;ame place, and with the intended inclinations of moving towards the Centre, till they had acquired tho&longs;e degrees of velocity, which at fir&longs;t &longs;ee­med good to the &longs;ame Divine Minde; the which being acquired, we la&longs;tly &longs;uppo&longs;e that they were turned round, each in his Sphere retaining the &longs;aid acquired velocity: it is now demanded, in what altitude and di&longs;tance from the Sun the place was where the &longs;aid Orbs were primarily created; and whether it be po&longs;&longs;ible that they might all be created in the &longs;ame place? To make this inve­&longs;tigation, we mu&longs;t take from the mo&longs;t skilfull A&longs;tronomers the magnitude of the Spheres in which the Planets revolve, and like­wi&longs;e the time of their revolutions: from which two cognitions is gathered how much (for example) Jupiter is &longs;wifter than Sa­turne; and being found (as indeed it is) that Jupiter moves more &longs;wiftly, it is requi&longs;ite, that departing from the &longs;ame altitude, Ju­piter be de&longs;cended more than Saturne, as we really know it is, its Orbe being inferiour to that of Saturne. But by proceeding for­wards, from the proportions of the two velocities of Jupiter and Saturne, and from the di&longs;tance between their Orbs, and from the proportion of acceleration of natural motion, one may finde in what altitude and di&longs;tance from the centre of their revolutions, was the place from whence they fir&longs;t departed. This found out, and agreed upon, it is to be &longs;ought, whether Mars de&longs;cending from thence to his Orb, the magnitude of the Orb, and the ve­locity of the motion, agree with that which is found by calcula­tion; and let the like be done of the Eartb, of Venus, and of Mercury; the greatne&longs;s of which Spheres, and the velocity of their motions, agree &longs;o nearly to what computation gives, that it is very admirable.

The circular mo­tion is never ac­quired naturally, without right mo­tion precede it. Circular motion perpetually uni­form.

The magnitude of the Orbs, and the velocity of the mo­tion of the Planets, an&longs;wer proportion­ably, as if de&longs;cend­ed from the &longs;ame place.

SAGR. I have hearkened to this conceit with extreme delight; and, but that I believe the making of the&longs;e 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 &longs;o readily; therefore we &longs;hall refer it to an­other time, and for the pre&longs;ent we will return to our fir&longs;t propo­&longs;al, going on there where we made digre&longs;&longs;ion; which, if I well remember, was about the proving the motion by a right line of no u&longs;e, in the ordinate parts of the World; and we did proceed to &longs;ay, that it was not &longs;o in circular motions, of which that which is made by the moveable in it &longs;elf, &longs;till retains it in the &longs;ame place, and that which carrieth the moveable by the circumference of a circle about its fixed centre, neither puts it &longs;elf, nor tho&longs;e about it in di&longs;order; for that &longs;uch a motion primarily is finite and terminate (though not yet fini&longs;hed and determined) but there is no point in the circumference, that is not the fir&longs;t and la&longs;t term in the cir­culation; and continuing it in the circumference a&longs;&longs;igned it, it leaveth all the re&longs;t, within and without that, free for the u&longs;e of others, without ever impeding or di&longs;ordering them. This being a motion that makes the moveable continually leave, and con­tinually arrive at the end; it alone therefore can primarily be u­niform; 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 &longs;ame term; and becau&longs;e in circular mo­tion, the moveable continually leaves the natural term, and con­tinually moveth towards the &longs;ame, therefore, in it, the repug­nance and inclination are always of equal force: from which e­quality re&longs;ults 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 &longs;ucce&longs;&longs;ively reiterating the circulations; which in an undeterminated line, and in a motion continually retarded or accelerated, cannot na­turally be. I &longs;ay, naturally; becau&longs;e the right motion which is retarded, is the violent, which cannot be perpetual; and the ac­celerate arriveth nece&longs;&longs;arily at the term, if one there be; and if there be none, it cannot be moved to it, becau&longs;e nature moves not whether it is impo&longs;&longs;ible to attain. I conclude therefore, that the circular motion can onely naturally con&longs;i&longs;t with natural bo­dies, parts of the univer&longs;e, and con&longs;tituted in an excellent di&longs;po­&longs;ure; and that the right, at the mo&longs;t that can be &longs;aid for it, is a&longs;&longs;igned by nature to its bodies, and their parts, at &longs;uch time as they &longs;hall be out of their proper places, con&longs;tituted in a depraved di&longs;po&longs;ition, and for that cau&longs;e needing to be redured by the &longs;hort­e&longs;t way to their natural &longs;tate. Hence, me thinks, it may ratio­nally be concluded, that for maintenance of perfect order among &longs;t the parts of the World, it is nece&longs;&longs;ary to &longs;ay, that moveables are moveable onely circularly; and if there be any that move not circularly, the&longs;e of nece&longs;&longs;ity are immoveable: there being no­thing but re&longs;t and circular motion apt to the con&longs;ervation of or­der. And I do not a little wonder with my &longs;elf, that Ari&longs;totle,who held that the Terre&longs;trial globe was placed in the centre of the World, and there remained immoveable, &longs;hould not &longs;ay, that of natural bodies &longs;ome are moveable by nature, and others immo­veable; e&longs;pecially having before defined Nature, to be the prin­ciple of Motion and Re&longs;t.

Finite and termi­nate circular mo­tions di&longs;order not the parts of the World.

In the circular mo­tion, every point in the circumference is the begining and end.

Circular motion onely is uniform.

Circular motion may be continued perpetually.

Right motion can­not naturally be perpetual.

Right motion a&longs;­&longs;igned to natural bodies, to reduce them to perfect or­der, when removed from their places.

Re&longs;t onely, and circular motion are apt to con&longs;erve or­der.

SIMPL. Ari&longs;totle, though of a very per&longs;picacious wit, would not &longs;train it further than needed: holding in all his argumen­tations, that &longs;en&longs;ible experiments were to be preferred before any rea&longs;ons founded upon &longs;trength of wit, and &longs;aid tho&longs;e which &longs;hould deny the te&longs;timony of &longs;en&longs;e de&longs;erved to be puni&longs;hed with the lo&longs;s of that &longs;en&longs;e; now who is &longs;o blind, that &longs;ees not the parts of the Earth and Water to move, as being grave, natural­ly downwards, namely, towards the centre of the Univer&longs;e, a&longs;­&longs;igned by nature her &longs;elf for the end and term of right motion deor&longs;ùm; and doth not likewi&longs;e &longs;ee the Fire and Air to move right upwards towards the Concave of the Lunar Orb, as to the natural end of motion &longs;ur&longs;ùm? And this being &longs;o manife&longs;tly &longs;een, and we being certain, that eadem est ratio totius & partium, why may we not a&longs;&longs;ert it for a true and manife&longs;t propo&longs;ition, that the natural motion of the Earth is the right motion ad medium, and that of the Fire, the right à medio?

Sen&longs;ible experi­ments are to be pre­ferred before hu­mane argument a­tions.

He who denies &longs;en&longs;e, de&longs;erves to be deprived of it. Sen&longs;e &longs;heweth that things grave move to the medium, and the light to the concave.

SALV. The mo&longs;t that you can pretend from this your Di&longs;­cour&longs;e, 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 re&longs;t, that is in &longs;hort reduced to a depraved and di&longs;­ordered di&longs;po&longs;ure, return to their place &longs;pontaneou&longs;ly, and there­fore naturally in a right motion, (it being granted, that eadem &longs;it ratio totius & partium) &longs;o it may be inferred, that the Terre&longs;trial Globe removed violently from the place a&longs;&longs;igned it by nature, it would return by a right line. This, as I have &longs;aid, is the mo&longs;t that can be granted you, and that onely for want of examination; but he that &longs;hall with exactne&longs;s revi&longs;e the&longs;e things, will fir&longs;t 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 demon&longs;trate the contra­ry, as you &longs;hall plainly &longs;ee in the an&longs;wers to the particular rea&longs;ons and experiments alledged by Ptolomey and Ari&longs;totle. Secondly, If another &longs;hould &longs;ay 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 rea&longs;on they naturally incline towards the centre of the Terre&longs;trial Globe, by which inclination they con­&longs;pire to form and pre&longs;erve it, what other All, or what other Centre would you find for the World, to which the whole Terrene Globe, being thence removed, would &longs;eek to return, that &longs;o the rea&longs;on of the Whole might be like to that of its parts? It may be added, That neither Ari&longs;totle, nor you can ever prove, that the Earth de facto is in the centre of the Univer&longs;e; but if any Centre may be a&longs;ligned to the Univer&longs;e, we &longs;hall rather find the Sun placed in it, as by the &longs;equel you &longs;hall under&longs;tand.

It is que&longs;tionable whether de&longs;cending weights move in a right line.

The Earth speri­cal by the con&longs;pi­ration of its parts to its Centre.

The Sun more pro­bably in the centre of the Vniver&longs;e, than the Earth.

Now, like as from the con&longs;entaneous con&longs;piration 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 them&longs;elves as much as is po&longs;&longs;ible together, they there &longs;phelically adapt them&longs;elves; why may we not believe that the Sun, Moon, and other mundane Bodies, be al&longs;o of a round figure, not by o­ther than a concordant in&longs;tinct, and natural concour&longs;e of all the parts compo&longs;ing them? Of which, if any, at any time, by any violence were &longs;eparated from the whole, is it not rea&longs;onable to think, that they would &longs;pontaneou&longs;ly and by natural in&longs;tinct re­turn? and in this manner to infer, that the right motion agreeth with all mundane bodies alike.

Natural inclina­tion 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 manife&longs;t Experience, and the Sen&longs;es them&longs;elves, you can never be convinced or removed from any o­pinion which you once conceit, therefore I will choo&longs;e rather to be &longs;ilent (for, contra negantes principia non e&longs;t di&longs;putandum) than contend with you. And in&longs;i&longs;ting on the things alledged by you even now (&longs;ince you que&longs;tion &longs;o much as whether grave move­ables have a right motion or no) how can you ever rationally de­ny, that the parts of the Earth; or, if you will, that ponderous matters de&longs;cend towards the Centre, with a right motion; when­as, if from a very high Tower, who&longs;e walls are vcry upright and perpendicular, you let them fall, they &longs;hall de&longs;cend gliding and &longs;liding by the Tower to the Earth, exactly in that very place where a plummet would fall, being hanged by a line fa&longs;tned above, ju&longs;t there, whence the &longs;aid weights were let fall? is not this a more than evident argument of the motions being right, and to­wards the Centre? In the &longs;econd place you call in doubt, whe­ther the parts of the Earth are moved, as Ari&longs;totle affirms, to­wards the Centre of the World; as if he had not rationally de­mon&longs;trated it by contrary motions, whil&longs;t he thus argueth; The motion of heavie bodies is contrary to that of the light: but the motion of the light is manife&longs;t 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 &longs;triveth to be united to that. The &longs;eeking in the next place, what a part of the Globe of the Sun or Moon would do, were it &longs;eparated from its whole, is vanity; becau&longs;e that there­by that is &longs;ought, which would be the con&longs;equence of an impo&longs;&longs;i­bility; in regard that, as Ari&longs;totle al&longs;o demon&longs;trates, the cœle&longs;tial bodies are impa&longs;&longs;ible, impenetrable, and infrangible; &longs;o that &longs;uch a ca&longs;e can never happen: and though it &longs;hould, and that the &longs;e­parated part &longs;hould return to its whole, it would not return as grave or light, for that the &longs;ame Ari&longs;totle proveth, that the Cœ­le&longs;tial Bodies are neither heavie nor light.

The right motion of grave bodies manife&longs;t to &longs;en&longs;e.

Arguments of A­ri&longs;totle, to prove that grave bodies move with an in­clination to arrive at the centre of the Vniver&longs;e.

Heavie bodies move towards the centre of the Earthper accidens.

To &longs;eek what would follow upon an impo&longs;&longs;ibility, is folly.

Cœle&longs;tial bodies neither heavie nor light, according toAri&longs;totle.

SALV. With what rea&longs;on I doubt, whether grave bodies move by a right and perpendicular line, you &longs;hall hear, as I &longs;aid be­fore, when I &longs;hall examine this particular argument. Touching the &longs;econd point, I wonder that you &longs;hould need to di&longs;cover the Paralogi&longs;m of Ari&longs;totle, being of it &longs;elf &longs;o manife&longs;t; and that you perceive not, that Ari&longs;totle &longs;uppo&longs;eth that which is in que&longs;ti­on: therefore take notice.

SIMPL. Pray Salviatus &longs;peak with more re&longs;pect of Ari&longs;totle: for who can you ever per&longs;wade, that he who was the fir&longs;t, only, and admirable explainer of the Syllogi&longs;tick forms of demon&longs;tration, of Elenchs, of the manner of di&longs;covering Sophi&longs;ms, Paralogi&longs;ms, and in &longs;hort, of all the parts of Logick, &longs;hould afterwards &longs;o notoriou&longs;ly equivocate in impo&longs;ing that for known, which is in que&longs;tion? It would be better, my Ma&longs;ters, fir&longs;t perfectly to under&longs;tand him, and then to try, if you have a minde, to oppo&longs;e him.

Ari&longs;totle cannot e­quivocate, being the inventer of Lo­gick.

SALV. Simplicius, we are here familiarly di&longs;cour&longs;ing among our &longs;elves, to inve&longs;tigate &longs;ome truth; I &longs;hall not be di&longs;plea&longs;ed that you di&longs;cover my errors; and if I do not follow the mind of Ari&longs;totle, freely reprehend me, and I &longs;hall take it in good part. Onely give me leave to expound my doubts, and to reply &longs;ome­thing to your la&longs;t words, telling you, that Logick, as it is well under&longs;tood, is the Organe with which we philo&longs;ophate; but as it may be po&longs;&longs;ible, that an Arti&longs;t may be excellent in making Or­gans, but unlearned in playing on them, thus he might be a great Logician, but unexpert in making u&longs;e of Logick; like as we have many that theorically under&longs;tand the whole Art of Poetry, and yet are unfortunate in compo&longs;ing but meer four Ver&longs;es; 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: Limn­ing is learnt by continual painting and de&longs;igning: Demon&longs;tration from the reading of Books full of demon&longs;trations, which are the Mathematical onely, and not the Logical. Now returning to our purpo&longs;e, I &longs;ay, that that which Ari&longs;totle &longs;eeth of the motion of light bodies, is the departing of the Fire from any part of the Superficies of the Terre&longs;trial 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 &longs;ame A­ri&longs;totle makes it to move to the concave of the Moon, but that this circumference is that of the World, or concentrick to it, &longs;o that to move towards this, is a moving towards that of the World, that he cannot affirm, unle&longs;s he &longs;uppo&longs;eth, That the Centre of the Earth, from which we &longs;ee the&longs;e light a&longs;cendent bodies to depart, be the &longs;ame with the Centre of the World; which is as much as to &longs;ay, that the terre&longs;trial Globe is con&longs;tituted in the mid&longs;t of the World: which is yet that of which we were in doubt, and which Aristotle intended to prove. And do you &longs;ay that this is not a manife&longs;t Paralogi&longs;m?

* A famous ItalianPainter.

Paralogi&longs;m of A­ri&longs;totle, in proving the Earth to be in the Centre of the World.

The Paralogi&longs;me of Ari&longs;totle another way di&longs;covered.

SAGR. This Argument of Ari&longs;totle appeared to me deficient al&longs;o, and non-concludent for another re&longs;pect; though it were granted, that that Circumference, to which the Fire directly mo­veth, be that which includeth the World: for that in a circle, not onely the centre, but any other point being taken, every move­able which departing thence, &longs;hall move in a right line, and to­wards any what&longs;oever part, &longs;hall without any doubt go towards the circumference, and continuing the motion, &longs;hall al&longs;o arrive thither; &longs;o that we may truly &longs;ay, that it moveth towards the circumference: but yet it doth not follow, that that which mo­veth by the &longs;ame line with a contrary motion, would go towards the centre, unle&longs;s when the point taken were the centre it &longs;elf, or that the motion were made by that onely line, which produced from the point a&longs;&longs;igned, pa&longs;&longs;eth thorow the centre. So that to &longs;ay, that Fire moving in a right line, goeth towards the circumfe­rence of the World, therefore the parts of the Earth which by the &longs;ame lines move with a contrary motion, go towards the cen­tre of the World, concludeth not, unle&longs;s then when it is pre­&longs;uppo&longs;ed, that the lines of the Fire prolonged pa&longs;s by the centre of the World; and becau&longs;e we know certainly of them, that they pa&longs;s by the centre of the Terre&longs;trial Globe (being perpendicu­lar to its &longs;uperficies, and not inclined) therefore to conclude, it mu&longs;t be &longs;uppo&longs;ed, that the centre of the Earth is the &longs;ame with the centre of the World; or at lea&longs;t, that the parts of the Fire and Earth de&longs;cend not, &longs;ave onely by one &longs;ole line which pa&longs;&longs;eth by the centre of the World. Which neverthele&longs;s is fal&longs;e, and re­pugnant to experience, which &longs;heweth 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, a&longs;cend always by lines perpendicular to the Superficies of the Terre&longs;tri­al Globe.

SALV. You do very ingeniou&longs;ly lead Ari&longs;totle to the &longs;ame in­convenience, Sagredus, &longs;hewing his manife&longs;t equivoke; but withal you add another incon&longs;i&longs;tency. We &longs;ee the Earth to be &longs;pherical, and therefore are certain that it hath its centre, to which we &longs;ee all its parts are moved; for &longs;o we mu&longs;t &longs;ay, whil&longs;t their motions are all perpendicular to the Superficies of the Earth; we mean, that as they move to the centre of the Earth, they move to their Whole, and to their Univer&longs;al Mother: and we are &longs;till far­ther &longs;o free, that we will &longs;uffer our &longs;elves to be per&longs;waded, that their natural in&longs;tinct is, not to go towards the centre of the Earth, but towards that of the Univer&longs;e; 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 &longs;aid la&longs;t, that the contending whether the parts of the Sun, Moon, or other cœle&longs;tial Body, &longs;eparated from their Whole, &longs;hould naturally return to it, is a vanity, for that the ca&longs;e is impo&longs;&longs;ible; it being clear by the Demon&longs;trations of Ari&longs;totle,that the cœle&longs;tial Bodies are impa&longs;&longs;ible, impenetrable, unparta­ble, &c. I an&longs;wer, that none of the conditions, whereby Aristo­tle di&longs;tingui&longs;heth the Cœle&longs;tial Bodies from Elementary, hath o­ther foundation than what he deduceth from the diver&longs;ity of the natural motion of tho&longs;e and the&longs;e; in&longs;omuch that it being deni­ed, that the circular motion is peculiar to Cœle&longs;tial Bodies, and affirmed, that it is agreeable to all Bodies naturally moveable, it is behoofull upon nece&longs;&longs;ary con&longs;equence to &longs;ay, 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 Cœle&longs;tial as to the E­lementary; or that Ari&longs;totle hath badly and erroneou&longs;ly dedu­ced tho&longs;e from the circular motion, which he hath a&longs;&longs;igned to Cœ­le&longs;tial Bodies.

Grave bodies may more rationally be affirmed to tend to the Centre of the Earth, than of the Vniver&longs;e.

The conditions and attributes which differ the cœle&longs;tial bodies from Ele­mentary, depend on the motions a&longs;&longs;ign­ed them by Ari&longs;t.

SIMPL. This manner of argumentation tends to the &longs;ubver&longs;i­on of all Natural Philo&longs;ophy, and to the di&longs;order and &longs;ubver&longs;ion of Heaven and Earth, and the whole Univer&longs;e; but I believe the Fundamentals of the Peripateticks are &longs;uch, 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 &longs;ubver&longs;ion, or the ruine of Philo&longs;ophy. As to Heaven, your fears are vain for that which you your &longs;elf hold unalterable and impa&longs;&longs;ible; as for the Earth, we &longs;trive to enoble and perfect it, whil&longs;t we make it like to the Cœle&longs;tial Bodies, and as it were place it in Heaven, whence your Philo&longs;ophers have exiled it. Philo&longs;ophy it &longs;elf cannot but receive benefit from our Di&longs;putes, for if our conceptions prove true, new Di&longs;coveries will be made; if fal&longs;e, the fir&longs;t Doctrine will be more confirmed. Rather be&longs;tow your care upon &longs;ome Philo&longs;ophers, and help and defend them; for as to the Science it &longs;elf, it cannot but improve. And that we may return to our purpo&longs;e, be plea&longs;ed freely to pro­duce what pre&longs;ents it &longs;elf to you in confirmation of that great dif­ference which Ari&longs;totle puts between the Cœle&longs;tial Bodies, and the Elementary parts of the World, in making tho&longs;e ingenerable, incorruptible, unalterable, &c. and this corruptible, alterable, &c.

The di&longs;putes and contradictions of Philo&longs;ophers may conduce to the benefit of Philo&longs;o­phy.

SIMPL. I &longs;ee not yet any need that Ari&longs;totle hath of help, &longs;tanding as he doth &longs;toutly and &longs;trongly on his feet; yea not be­ing yet a&longs;&longs;aulted, much le&longs;s foiled by you. And what ward will you choo&longs;e in this combate for this fir&longs;t blow? Aristotle writeth, that whatever is generated, is made out of a contrary in &longs;ome &longs;ubject, and likewi&longs;e is corrupted in &longs;ome certain &longs;ubject from a contrary into a contrary; &longs;o that (ob&longs;erve) corruption and ge­neration is never but onely in contraries; If therefore to a Cœ­le&longs;tial Body no contrary can be a&longs;&longs;igned, 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 in­generable and incorruptible, This fundamental fir&longs;t confirmed, it immediately followeth of con&longs;equence, that it is inaugmenta­ble, inalterable, impa&longs;&longs;ible, and finally eternal, and a propor­tionate habitation to the immortal Deities, conformable to the opinion even of all men that have any conceit of the Gods. He afterwards confirmeth the &longs;ame by &longs;en&longs;e; in regard, that in all times pa&longs;t, according to memory or tradition, we &longs;ee nothing re­moved, 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 reci­ting them all, it is &longs;ufficiently demon&longs;trated, &longs;ince fimple motions are but three, to the medium, from the medium, and about the medium, of which the two right, &longs;ur&longs;um and deor&longs;um, are mani­fe&longs;tly contrary; and becau&longs;e one onely hath onely one for con­trary, therefore there re&longs;ts no other motion which may be contra­ry to the circular. You &longs;ee the &longs;ubtle and mo&longs;t concluding di&longs;­cour&longs;e of Ari&longs;totle, whereby he proveth the incorruptibility of Heaven.

Ari&longs;totles di&longs;cour&longs;e to prove the incor­ruptibility of Hea­ven.

Generation & cor­ruption is onely a­mong&longs;t contraries, according to Ari&longs;t.

To the circular motion no other motion is contrary.

Heaven an habi­tation for the imm­ortal Gods.

Immutability of Heaven evident to &longs;ex&longs;e.

He proveth that the circular motion hath no contrary.

SALV. This is nothing more, &longs;ave the pure progre&longs;s of Ari&longs;to­tle, by me hinted before; wherein, be&longs;ides that I affirm, that the motion which you attribute to the Cœle&longs;tial Bodies agreeth al&longs;o to the Earth, its illation proves nothing. I tell you therefore, that that circular motion which you a&longs;&longs;ign to Cœle&longs;tial Bodies, &longs;uiteth al&longs;o to the Earth, from which, &longs;uppo&longs;ing that the re&longs;t of your di&longs;cour&longs;e were concludent, will follow one of the&longs;e three things, as I told you a little before, and &longs;hall repeat; namely, either that the Earth it &longs;elf is al&longs;o ingenerable, and incorruptible, as the Cœle&longs;tial bodies; or that the Cœle&longs;tial bodies are, like as the Elementary generable, alterable &c. or that this difference of motion hath nothing to do with Generation and Corruption. The di&longs;cour&longs;e of Ari&longs;totle, and yours al&longs;o contain many Propo&longs;i­tions not to be lightly admitted, and the better to examine them, it will be convenient to reduce them to the mo&longs;t ab&longs;tracted and di&longs;tinct that can be po&longs;&longs;ible; and excu&longs;e me Sagredus, if haply with &longs;ome tediou&longs;ne&longs;s you hear me oft repeat the &longs;ame things, and fancie that you &longs;ee me rea&longs;&longs;ume my argument in the pub­lick circle of Di&longs;putations. You &longs;ay Generation and Corrupti­on are onely made where there are contraries; contraries are onely among&longs;t &longs;imple natural bodies, moveable with contrary motions; contrary motions are onely tho&longs;e which are made by a right line between contrary terms; and the&longs;e are onely two, that is to &longs;ay, from the medium, and towards the medium; and &longs;uch motions belong to no other natural bodies, but to the Earth,the Fire, and the other two Elements: therefore Generation and Corruption is onely among&longs;t the Elements. And becau&longs;e the third &longs;imple 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 &longs;uch motion agreeth, wants a contrary; and having no contrary is ingenerable and incorruptible, &c. Becau&longs;e where there is no contrariety, there is no generation or corruption, &c.But &longs;uch motion agreeth onely with the Cœle&longs;tial bodies; there­fore onely the&longs;e are ingenerable, incorruptible, &c. And to begin, I think it a more ea&longs;ie thing, and &longs;ooner done to re&longs;olve, whether the Earth (a mo&longs;t va&longs;t Body, and for its vicinity to us, mo&longs;t tractable) moveth with a &longs;peedy motion, &longs;uch as its revo­lution about its own axis in twenty four hours would be, than it is to under&longs;tand and re&longs;olve, whether Generation and Corruption ari&longs;eth from contrariety, or el&longs;e whether there be &longs;uch things as generation, corruption and contrariety in nature. And if you, Simplicius, can tell me what method Nature ob&longs;erves in working, when &longs;he in a very &longs;hort time begets an infinite number of flies from a little vapour of the Mu&longs;t of wine, and can &longs;hew me which are there the contraries you &longs;peak of, what it is that corrupteth, and how; I &longs;hould think you would do more than I can; for I profe&longs;s I cannot comprehend the&longs;e things. Be&longs;ides, I would ve­ry gladly under&longs;tand how, and why the&longs;e corruptive contraries are &longs;o favourable to Daws, and &longs;o cruel to Doves; &longs;o indulgent to Stags, and &longs;o ha&longs;ty to Hor&longs;es, that they do grant to them many more years of life, that is, of incorruptibility, than weeks to the&longs;e. Peaches and Olives are planted in the &longs;ame &longs;oil, expo&longs;ed to the &longs;ame heat and cold, to the &longs;ame wind and rains, and, in a word, to the &longs;ame contrarieties; and yet tho&longs;e decay in a &longs;hort time, and the&longs;e live many hundred years. Furthermore, I never was thorowly &longs;atisfied about this &longs;ub&longs;tantial tran&longs;mutation (&longs;till keep­ing within pure natural bounds) whereby a matter becometh &longs;o transform'd, that it &longs;hould be nece&longs;&longs;arily &longs;aid to be de&longs;troy'd, &longs;o that nothing remaineth of its fir&longs;t being, and that another body quite differing there-from &longs;hould be thence produced; and if I fancy to my &longs;elf a body under one a&longs;pect, and by and by under another very different, I cannot think it impo&longs;&longs;ible but that it may happen by a &longs;imple tran&longs;po&longs;ition of parts, without corrupting or ingendring any thing a-new; for we &longs;ee &longs;uch kinds of Metamor­pho&longs;es dayly: &longs;o that to return to my purpo&longs;e, I an&longs;wer you, that ina&longs;much as you go about to per&longs;wade 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 argu­ments more difficult indeed, but no le&longs;s concluding, will prove the contrary.

Its ea&longs;ier to prove the Earth to move, than that corrupti­on is made by con­traries.

Bare tran&longs;po&longs;ition of parts may repre­&longs;ent bodies under diver&longs;e asp cts.

SAGR. Pardon me, Salviatus, if I interrupt your di&longs;cour&longs;e, which, as it delights me much, for that I al&longs;o am gravel'd with the &longs;ame doubts; &longs;o I fear that you can never conclude the &longs;ame, without altogether digre&longs;&longs;ing from your chief de&longs;ign: therefore if it be permitted to proceed in our fir&longs;t argument, I &longs;hould think that it were convenient to remit this que&longs;tion of generation and corruption to another di&longs;tinct and &longs;ingle conference; as al&longs;o, if it &longs;hall plea&longs;e you and Simplicius, we may do by other particular que&longs;tions which may fall in the way of our di&longs;cour&longs;e; which I will keep in my mind to propo&longs;e, and exactly di&longs;cu&longs;s them &longs;ome other time. Now as for the pre&longs;ent, &longs;ince you &longs;ay, that if Ari­&longs;totle deny circular motion to the Earth in common with other bodies Cœle&longs;tial, it chence will follow, that the &longs;ame which be­falleth the Earth, to ito being generable, alterable, &c. will hold al&longs;o of Heaven, let us enquire no further if there be &longs;uch 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 &longs;uffer my ears to hear it que&longs;tion'd, whether generation and corruption be in rerum naturà, it being a thing which we have continually before our eyes, and whereof Ari&longs;totlehath written two whole Books. But if you go about to deny the Principles of Sciences, and que&longs;tion things mo&longs;t manife&longs;t, who knows not, but that you may prove what you will, and maintain any Paradox? And if you do not dayly &longs;ee herbs, plants, ani­mals to generate and corrupt, what is it that you do &longs;ee? Al&longs;o, 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 conden&longs;e into Clouds, Rains, Hails and Storms?

By denying Prin­ciples in the Scien­ces, any Paradox may be maintain­ed.

SAGR. Yes, we &longs;ee the&longs;e things indeed, and therefore will grant you the di&longs;cour&longs;e of Ari&longs;totle, as to this part of generation and corruption made by contraries; but if I &longs;hall conclude by virtue of the &longs;ame propo&longs;itions which are granted to Ari&longs;totle,that the Cœle&longs;tial bodies them&longs;elves are al&longs;o generable and cor­ruptible, a&longs;well as the Elementary, what will you &longs;ay then?

SIMPL. I will &longs;ay you have done that which is impo&longs;&longs;ible to be done.

SAGR. Go to; tell me, Simplicius, are not the&longs;e affections contrary to one another?

SIMPL. Which?

SAGR. Why the&longs;e; Alterable, unalterable; pa&longs;&longs;ible, ^{*} impa&longs;­&longs;ible; generable, ingenerable; corruptible, incorruptible?

* Or, Impatible.

SIMPL. They are mo&longs;t contrary.

SAGR. Well then, if this be true, and it be al&longs;o granted, that Cœle&longs;tial Bodies are ingenerable and incorruptible; I prove that of nece&longs;&longs;ity Cœle&longs;tial Bodies mu&longs;t be generable and corru­ptible.

SIMPL. This mu&longs;t needs be a Sophi&longs;m.

SAGR. Hear my Argument, and then cen&longs;ure and re&longs;olve it. Cœle&longs;tial Bodies, for that they are ingenerable and incorruptible, have in Nature their contraries, which are tho&longs;e Bodies that be generable and corruptible; but where there is contrariety, there is al&longs;o generation and corruption; therefore Cœle&longs;tial Bodies are generable and corruptible.

Cœlestial Bodies are generable and corruptible, be­cau&longs;e they are in­generable and in­corruptible.

SIMPL. Did I not &longs;ay it could be no other than a Sophi&longs;m? This is one of tho&longs;e forked Arguments called Soritæ: like that of the Cretan, who &longs;aid that all Cretans were lyars; but he as being a Cretan, had told a lye, in &longs;aying that the Cretans were ly­ars; it followed therefore, that the Cretans were no lyars, and con&longs;equently that he, as being a Cretan, had &longs;poke truth: And yet in &longs;aying the Cretans were lyars, he had &longs;aid true, and com­prehending him&longs;elf as a Cretan, he mu&longs;t con&longs;equently be a lyar. And thus in the&longs;e kinds of Sophi&longs;ms a man may dwell to eternity, and never come to any conclu&longs;ion.

The forked Syllo­gi&longs;m cal'd *cwri/hhs.

SAGR. You have hitherto cen&longs;ured it, it remaineth now that you an&longs;wer it, &longs;hewing the fallacie.

SIMPL. As to the re&longs;olving of it, and finding out its fallacie, do you not in the fir&longs;t place &longs;ee a manife&longs;t contradiction in it? Cœle&longs;tial Bodies are ingenerable and incorruptible; Ergo, Cœle­&longs;tial Bodies are generable and corruptible. And again, the con­trariety is not betwixt the Cœle&longs;tial Bodies, but betwixt the E­lements, which have the contrariety of the Motions, &longs;ur&longs;ùm and deor&longs;ùm, 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.

Among&longs;t Cœle&longs;tial Bodies there is no contrariety.

SAGR. Fair and &longs;oftly, Simplicius; this contrariety whereby you &longs;ay &longs;ome &longs;imple Bodies become corruptible, re&longs;ides it in the &longs;ame Body which is corrupted, or el&longs;e hath it relation to &longs;ome o­other? I &longs;ay, for example, the humidity by which a piece of Earth is corrupted, re&longs;ides it in the &longs;ame Earth or in &longs;ome other bodie, which mu&longs;t 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 fir&longs;t contraries, cannot be in the &longs;ame Subject, &longs;o neither can moi&longs;t and dry, hot and cold: you mu&longs;t therefore con&longs;equently acknowledg that when a bodie cor­rupteth, it is occa&longs;ioned by &longs;ome quality re&longs;iding in another con­trary to its own: therefore to make the Cœle&longs;tial Body become corruptible, it &longs;ufficeth that there are in Nature, bodies that have a contrariety to that Cœle&longs;tial body; and &longs;uch are the Elements, if it be true that corruptibility be contrary to incorruptibility.

Contraries which are the cau&longs;es of corruption, re&longs;ide not in the &longs;ame bo­dy that corrupteth.

SIMPL. This &longs;ufficeth not, Sir; The Elements alter and cor­rupt, becau&longs;e they are intermixed, and are joyn'd to one another, and &longs;o may exerci&longs;e their contrariety; but Cœle&longs;tial bodies are &longs;eparated from the Elements, by which they are not &longs;o much as toucht, though indeed they have an influence upon the Elements. It is requi&longs;ite, if you will prove generation and corruption in Cœ­le&longs;tial bodies, that you &longs;hew, that there re&longs;ides contrarieties be­tween them.

Cœle&longs;tial Bodies touch, but are not touched by the E­lements.

SAGR. See how I will find tho&longs;e contrarieties between them. The fir&longs;t fountain from whence you derive the contrariety of the Elements, is the contrariety of their motions upwards and down­wards: it therefore is nece&longs;&longs;ary that tho&longs;e Principles be in like manner contraries to each other, upon which tho&longs;e motions de­pend. and becau&longs;e that is moveable upwards by lightne&longs;s, and this downwards by gravitv, it is nece&longs;&longs;ary that lightne&longs;s and gravity are contrary to each other: no le&longs;s are we to believe tho&longs;e other Principles to be contraries, which are the cau&longs;es that this is heavy, and that light: but by your own confe&longs;&longs;ion, levity and gravity follow as con&longs;equents of rarity and den&longs;ity; therefore rarity and den&longs;ity &longs;hall be contraries: the which conditions or affections are &longs;o amply found in Cœle&longs;tial bodies, that you e­&longs;teem the &longs;tars to be onely more den&longs;e parts of their Heaven: and if this be &longs;o, it followeth that the den&longs;ity of the &longs;tars exceeds that of the re&longs;t of Heaven, by almo&longs;t infinite degrees: which is manife&longs;t, in that Heaven is infinitely tran&longs;parent, and the &longs;tars extremely opacous; and for that there are there above no other qualities, but more and le&longs;s den&longs;ity and rarity, which may be cau&longs;es of the greater or le&longs;s tran&longs;parency. There being then &longs;uch contrariety between the Cœleftial bodies, it is nece&longs;&longs;ary that they al&longs;o be generable and corruptible, in the &longs;ame manner as the Elementary bodies are; or el&longs;e that contrariety is not the cau&longs;e of corruptibility, &c.

Gravity & levity, varity and den&longs;ity, are contrary qua­lities.

The &longs;tars infinitely &longs;urpa&longs;s the &longs;ub­&longs;tance of the re&longs;t of Heaven in den&longs;ity.

Rarity & den&longs;ity in Cœle&longs;tial bodies, is different from the rarity & den­&longs;ity of the elements.

SIMPL. There is no nece&longs;&longs;ity either of one or the other, for that den&longs;ity and rarity in Cœle&longs;tial bodies, are not contraries to each 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 le&longs;s matter in proportion to quantity: now much and little, &longs;peak onely a relative oppo&longs;ition, that is, the lea&longs;t of oppo&longs;itions, and which hath nothing to do with generation and corruption.

SAGR. Therefore affirming, that den&longs;ity and rarity, which a­mong&longs;t the Elements &longs;hould be the cau&longs;e of gravity and levity, which may be the cau&longs;es of contrary motions &longs;ur&longs;ùm and deor­&longs;ùm, on which, again, dependeth the contrarieties for generation and corruption; it &longs;ufficeth not that they be tho&longs;e den&longs;ne&longs;&longs;es and rarene&longs;&longs;es which under the &longs;ame quantity, or (if you will) ma&longs;s contain much or little matter, but it is nece&longs;&longs;ary that they be den&longs;­ne&longs;&longs;es and rarene&longs;&longs;es cau&longs;ed by the primary qualities, hot and cold, otherwi&longs;e they would operate nothing at all: but if this be &longs;o, Ari&longs;totle hath deceived us, for that he &longs;hould have told it us at fir&longs;t, and &longs;o have left written that tho&longs;e &longs;imple bodies are gene­rable and corruptible, that are moveable with &longs;imple motions upwards and downwards, dependent on levity and gravity, cau­&longs;ed by rarity and den&longs;ity, made by much or little matter, by rea&longs;on of heat and cold; and not to have &longs;taid at the &longs;imple mo­tion &longs;ur&longs;ùm and deor&longs;ùm: for I a&longs;&longs;ure you that to the making of bodies heavy or light, whereby they come to be moved with contrary motions, any kind of den&longs;ity and rarity &longs;ufficeth, whe­ther it proceed from heat and cold, or what el&longs;e you plea&longs;e; for heat and cold have nothing to do in this affair: and you &longs;hall upon experiment find, that a red hot iron, which you mu&longs;t grant to have heat, weigheth as much, and moves in the &longs;ame manner as when it is cold. But to overpa&longs;s this al&longs;o, how know you but that Cœle&longs;tial rarity and den&longs;ity depend on heat and cold?

Ari&longs;totle defective in a&longs;&longs;igning the cau&longs;es why the ele­ments are genera­ble & corruptible.

SIMPL. I know it, becau&longs;e tho&longs;e qualities are not among&longs;t Cœle&longs;tial bodies, which are neither hot nor cold.

SALV. I &longs;ee we are again going about to engulph our &longs;elves in a bottomle&longs;s ocean, where there is no getting to &longs;hore; for this is a Navigation without Compa&longs;s, Stars, Oars or Rudder: &longs;o that it will follow either that we be forced to pa&longs;s from Shelf to Shelf, or run on ground, or to &longs;ail continually in danger of being lo&longs;t. Therefore, if according to your advice we &longs;hall proceed in our main de&longs;ign, we mu&longs;t of nece&longs;&longs;ity for the pre&longs;ent overpa&longs;s this general con&longs;ideration, whether direct motion be nece&longs;&longs;ary in Na­ture, and agree with &longs;ome bodies; and come to the particular demon&longs;trations, ob&longs;ervations and experiments; propounding in the fir&longs;t place all tho&longs;e that have been hitherto alledged by Ari­&longs;totle, Ptolomey, and others, to prove the &longs;tability of the Earth, en­deavouring in the next place to an&longs;wer them: and producing in the la&longs;t place, tho&longs;e, by which others may be per&longs;waded, that the Earth is no le&longs;s than the Moon, or any other Planet to be num­bered among&longs;t natural bodies that move circularly.

SAGR. I &longs;hall the more willingly incline to this, in that I am better &longs;atisfied with your Architectonical and general di&longs;cour&longs;e, than with that of Ari&longs;totle, for yours convinceth me without the lea&longs;t &longs;cruple, and the other at every &longs;tep cro&longs;&longs;eth my way with &longs;ome block. And I &longs;ee no rea&longs;on why Simplicius &longs;hould not be pre&longs;ently &longs;atisfied with the Argument you alledg, to prove that there can be no &longs;uch thing in nature as a motion by a right line, if we do but pre&longs;uppo&longs;e that the parts of the Univer&longs;e are di&longs;po­&longs;ed in an excellent con&longs;titution and perfect order.

SALV. Stay a little, good Sagredus, for ju&longs;t now a way comes into my mind, how I may give Simplicius &longs;atisfaction, provided that he will not be &longs;o &longs;trictly wedded to every expre&longs;&longs;ion of A­ri&longs;totle, as to hold it here&longs;ie to recede in any thing from him. Nor is there any que&longs;tion to be made, but that if we grant the excel­lent di&longs;po&longs;ition and perfect order of the parts of the Univer&longs;e, as to local &longs;cituation, that then there is no other but the circular motion, and re&longs;t; for as to the motion by a right line, I &longs;ee not how it can be of u&longs;e for any thing, but to reduce to their natural con&longs;titution, &longs;ome integral bodies, that by &longs;ome accident were re­mov'd and &longs;eparated from their whole, as we &longs;aid above.

Let us now con&longs;ider the whole Terre&longs;trial Globe, and enquire the be&longs;t we can, whether it, and the other Mundane bodies are to con&longs;erve them&longs;elves in their perfect and natural di&longs;po&longs;ition. It is nece&longs;&longs;ary to &longs;ay, either that it re&longs;ts and keeps perpetually im­moveable in its place; or el&longs;e that continuing always in its place, it revolves in its &longs;elf; or that it turneth about a Centre, moving by the circumference of a circle. Of which accidents, both Ari­&longs;totle and Ptolomey, and all their followers &longs;ay, that it hath ever ob&longs;erved, and &longs;hall continually keep the fir&longs;t, that is, a perpetual re&longs;t in the &longs;ame place. Now, why, I pray you, ought they not to have &longs;aid, that its natural affection is to re&longs;t immoveable, ra­ther than to make natural unto it the motion ^{*} downwards, with which motion it never did or &longs;hall move? And as to the motion by a right line, they mu&longs;t grant us that Nature maketh u&longs;e of it to reduce the &longs;mall parts of the Earth, Water, Air, Fire, and every other integral Mundane body to their Whole, when any of them by chance are &longs;eparated, and &longs;o tran&longs;ported out of their proper place; if al&longs;o haply, &longs;ome circular motion might not be found to be more convenient to make this re&longs;titution. In my judg­ment, this primary po&longs;ition an&longs;wers much better, even according to Ari&longs;totles own method, to all the other con&longs;equences, than to attribute the &longs;traight motion to be an intrin&longs;ick and natural principle of the Elements. Which is manife&longs;t, for that if I aske the Peripatetick, if, being of opinion that Cœle&longs;tial bodies are incorruptibe and eternal, he believeth that the Terre&longs;tial Globe is not &longs;o, but corruptible and mortal, &longs;o that there &longs;hall come a time, when the Sun and Moon and other Stars, continuing their beings and operations, the Earth &longs;hall not be found in the World, but &longs;hall with the re&longs;t of the Elements be de&longs;troyed and annihilated, I am certain that he would an&longs;wer me, no: therefore generation and corruption is in the parts and not in the whole; and in the parts very &longs;mall and &longs;uperficial, which are, as it were, incen&longs;ible in compari&longs;on of the whole ma&longs;&longs;e. And becau&longs;e Ari&longs;totle deduceth generation and corruption from the contrariety of &longs;treight motions, let us remit &longs;uch motions to the parts, which onely change and decay, and to the whole Globe and Sphere of the Elements, let us a&longs;cribe either the circular mo­tion, or a perpetual con&longs;i&longs;tance in its proper place: the only affections apt for perpetuation, and maintaining of perfect order. This which is &longs;poken of the Earth, may be &longs;aid with the &longs;ame rea&longs;on of Fire, and of the greate&longs;t part of the Air; to which Elements, the Peripateticks are forced to a&longs;cribe for intrin&longs;ical and natural, a motion wherewith they were never yet moved, nor never &longs;hall be; and to call that motion preternatural to them, wherewith, if they move at all, they do and ever &longs;hall move. This I &longs;ay, becau&longs;e they a&longs;&longs;ign to the Air aud Fire the motion upwards, wherewith tho&longs;e Elements were never moved, but only &longs;ome parts of them, and tho&longs;e were &longs;o moved onely in or­der to the recovery of their perfect con&longs;titution, when they were out of their natural places; and on the contrary they call the circular motion preternatural to them, though they are thereby ince&longs;&longs;antly moved: forgeting, as it &longs;eemeth, what Ari&longs;totle oft in­culcateth, that nothing violent can be permanent.

Ari&longs;t. & Ptolomey make the Terre­strial Globe immo­veable.

It is better to &longs;ay, that the Terre&longs;tri­al Globe naturally resteth, than that it moveth directly downwards.

*The word is, all' ingiù, which the Latine ver&longs;ion ren­dreth &longs;ur&longs;ùm,which is quite con­trary to the Au­thors &longs;en&longs;e.

Right Motion with more rea&longs;on attributed to the parts, than to the whole Elements.

The Peripateticks improperly a&longs;&longs;ign tho&longs;e motious to the Elements for Natural, with which they never were moved, and tho&longs;e for Preter­natural with which they alwayes are moved.

SIMPL. To all the&longs;e we have very pertinent an&longs;wers, which I for this time omit, that we may come to the more particular rea&longs;ons, and &longs;en&longs;ible experiments, which ought in conclu&longs;ion to be oppo&longs;ed, as Ari&longs;totle &longs;aitn well, to whatever humane rea&longs;on can pre&longs;ent us with.

Sen&longs;ible experi­ments to be prefer­red to humane Arguments.

SAGR. What hath been &longs;poken hitherto, &longs;erves to clear up unto us which of the two general di&longs;cour&longs;es carrieth with it mo&longs;t of probability, I mean that of Ari&longs;totle, which would per&longs;wade us, that the &longs;ublunary bodies are by nature generable, and corru­ptible, &c. and therefore mo&longs;t different from the e&longs;&longs;ence of Cœ­leftial bodies, which are impa&longs;&longs;ible, ingenerable, incorruptible, &c. drawn from the diver&longs;ity of &longs;imple motions; or el&longs;e this of Salviatus, who &longs;uppo&longs;ing the integral parts of the World to be di&longs;po&longs;ed in a perfect con&longs;titution, excludes by nece&longs;&longs;ary confe­quence the right or &longs;traight motion of &longs;imple natural bodies, as being of no u&longs;e in nature, and e&longs;teems the Earth it &longs;elf al&longs;o to be one of the Cœle&longs;tial bodies adorn'd with all the prerogatives that agree with them; which la&longs;t di&longs;cour&longs;e is hitherto much more likely, in my judgment, than that other. Therefore re­&longs;olve, Simplicius, to produce all the particular rea&longs;ons, experi­ments and ob&longs;ervations, as well Natural as A&longs;tronomical, that may &longs;erve to per&longs;wade us that the Earth differeth from the Cœ­le&longs;tial bodies, is immoveable, and &longs;ituated in the Centre of the World, and what ever el&longs;e excludes its moving like to the Planets, as Jupiter or the Moon, &c. And Salviatus will be plea&longs;ed to be &longs;o civil as to an&longs;wer to them one by one.

SIMPL. See here for a beginning, two mo&longs;t convincing Argu­ments to demon&longs;trate the Earth to be mo&longs;t different from the Cœle&longs;tial bodies. Fir&longs;t, the bodies that are generable, corru­ptible, alterable, &c. are quite different from tho&longs;e that are in­generable, incorruptible, unalterable, &c. But the Earth is ge­nerable, corruptible, alterable, &c. and the Cœle&longs;tial bodies in­generable, incorruptible, unalterable, &c. Therefore the Earth is quite different from the Cœle&longs;tial bodies.

SAGR. By your fir&longs;t Argument you &longs;pread the Table with the &longs;ame Viands, which but ju&longs;t now with much adoe were voided.

SIMPL. Hold a little, Sir, and take the re&longs;t along with you, and then tell me if this be not different from what you had be­fore. In the former, the Minor was proved à priori, & now you &longs;ee it proved à po&longs;teriori: Judg then if it be the &longs;ame. I prove the Minor, therefore (the Major being mo&longs;t manife&longs;t) by &longs;en&longs;ible ex­perience, which &longs;hews us that in the Earth there are made conti­nual generations, corruptions, alterations, &c. which neither our &longs;en&longs;es, nor the traditions or memories of our Ance&longs;tors, ever &longs;aw an in&longs;tance of in Heaven; therefore Heaven is unalterable, &c.and the Earth alterable, &c. and therefore different from Hea­ven. I take my &longs;econd Argument from a principal and e&longs;&longs;ential accident, and it is this. That body which is by its nature ob­&longs;cure and deprived of light, is divers from the luminous and &longs;hi­ning bodies; but the Earth is ob&longs;cure and void of light, and the Cœle&longs;tial bodies &longs;plendid, and full of light; Ergo, &c. An&longs;wer to the&longs;e Arguments fir&longs;t, that we may not heap up too many, and then I will alledge others.

Heaven immuta­ble, becau&longs;e there never was any mu­tation &longs;een in it.

Bodies naturally lucid, are different from tho&longs;e which are by nature ob­&longs;cure.

SALV. As to the fir&longs;t, the &longs;tre&longs;&longs;e whereof you lay upon ex­perience, I de&longs;ire that you would a little more di&longs;tinctly produce me the alteration which you &longs;ee made in the Earth, and not in Heaven; upon which you call the Earth alterable, and the Hea­vens not &longs;o.

SIMPL. I &longs;ee in the Earth, plants and animals continually ge­nerating and decaying; winds, rains, tempe&longs;ts, &longs;torms ari&longs;ing; and in a word, the a&longs;pect of the Earth to be perpetually metamorpho­&longs;ing; none of which mutations are to be di&longs;cern'd in the Cœle&longs;tial bodies; the con&longs;titution and figuration of which is mo&longs;t punctu­ally 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 &longs;elf with the&longs;e vi&longs;ible, or to &longs;ay better, &longs;een experiments, you mu&longs;t con&longs;equently account China and America Cœle&longs;tial bodies, for doubtle&longs;&longs;e you never beheld in them the&longs;e alterations which you &longs;ee here in Italy, and that therefore according to your apprehen&longs;ion they are inal­terable.

SIMPL. Though I never did &longs;ee the&longs;e alterations &longs;enfibly in tho&longs;e places, the relations of them are not to be que&longs;tioned; be&longs;ides that, cum eadem &longs;it ratio totius, & partium, tho&longs;e Countreys being a part of the Earth, as well as ours, they mu&longs;t of nece&longs;&longs;ity be alterable as the&longs;e are.

SALV. And why have you not, without being put to believe other mens relations, examined and ob&longs;erved tho&longs;e alterations with your own eyes?

SIMPL. Becau&longs;e tho&longs;e places, be&longs;ides that they are not ex­po&longs;ed to our eyes, are &longs;o remote, that our &longs;ight cannot reach to comprehend therein &longs;uch like mutations.

SALV. See now, how you have unawares di&longs;covered the falla­cy of your Argument; for, if you &longs;ay that the alterations that are &longs;een on the Earth neer at hand, cannot, by rea&longs;on of the too great di&longs;tance, be &longs;een in America, much le&longs;&longs;e can you &longs;ee them in the Moon, which is &longs;o many hundred times more remote: And if you believe the alterations in Mexico upon the report of tho&longs;e that come from thence, what intelligence have you from the Moon, to a&longs;&longs;ure you that there is no &longs;uch alterations in it? Therefore, from your not &longs;eeing any alterations in Heaven, whereas, if there were any &longs;uch, you could not &longs;ee them by rea­&longs;on of their too great di&longs;tance, and from your not having intel­ligence thereof, in regard that it cannot be had, you ought not to argue, that there are no &longs;uch alterations; howbeit, from the &longs;eeing and ob&longs;erving of them on Earth, you well argue that therein &longs;uch there are.

SIMPL. I will &longs;hew &longs;o great mutations that have befaln on the Earth; that if any &longs;uch had happened in the Moon, they might very well have been ob&longs;erved here below. We find in very antient records, that heretofore at the Streights of Gibraltar,the two great Mountains Abila, and Calpen, were continued to­gether by certain other le&longs;&longs;e Mountains which there gave check to the Ocean: but tho&longs;e Hills, being by &longs;ome cau&longs;e or other &longs;e­parated, and a way being opened to the Sea to break in, it made &longs;uch an inundation, that it gave occa&longs;ion to the calling of it &longs;ince the Mid-land Sea: the greatne&longs;s whereof con&longs;idered, and the di­vers a&longs;pect the &longs;urface of the Water and Earth then made, had it been beheld afar off, there is no doubt but &longs;o great a change might have been di&longs;cerned by one that was then in the Moon; as al&longs;o to us inhabitants of the Earth, the like alterations would be perceived in the Moon; but we find not in antiquity, that e­ver there was &longs;uch a thing &longs;een; therefore we have no cau&longs;e to &longs;ay, that any of the Cœle&longs;tial bodies are alterable, &c.

The Mediterr ani­an Sea made by the &longs;eparation of Abi­la and Calpen.

SALV. That &longs;o great alterations have hapned in the Moon, I dare not &longs;ay, but for all that, I am not yet certain but that &longs;uch changes might occur; and becau&longs;e &longs;uch a mutation could onely repre&longs;ent unto us &longs;ome kind of variation between the more clear, and more ob&longs;cure parts of the Moon, I know not whether we have had on Earth ob&longs;ervant Selenographers, who have for any con&longs;iderable number of years, in&longs;tructed us with &longs;o exact Seleno­graphy, as that we &longs;hould confidently conclude, that there hath no &longs;uch change hapned in the face of the Moon; of the figura­tion of which I find no more particular de&longs;cription, than the &longs;ay­ing of &longs;ome, that it repre&longs;ents 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 &longs;ay Heaven is un­alterable, becau&longs;e that in the Moon, or other Cœle&longs;tial bodies, no &longs;uch alterations are &longs;een, as di&longs;cover them&longs;elves on Earth, is a bad illation, and concludeth nothing.

SAGR. And there is another odd kind of &longs;cruple in this Argu­ment of Simplicius, running in my mind, which I would gladly have an&longs;wered; therefore I demand of him, whether the Earth before the Mediterranian inundation was generable and corrupti­ble, or el&longs;e began then &longs;o to be?

SIMPL. It was doubtle&longs;s generable and corruptible al&longs;o be­fore that time; but that was &longs;o va&longs;t a mutation, that it might have been ob&longs;erved as far as the Moon.

SAGR. Go to; if the Earth was generable and corruptible before that Inundation, why may not the Moon be &longs;o like­wi&longs;e without &longs;uch a change? Or why &longs;hould that be nece&longs;&longs;ary in the Moon, which importeth nothing on Earth?

SALV. It is a &longs;hrewd que&longs;tion: But I am doubtfull that Sim­plicius a little altereth the Text of Ari&longs;totle, and the other Peri­patelicks, who &longs;ay, they hold the Heavens unalterable, for that they &longs;ee therein no one &longs;tar generate or corrupt, which is proba­bly a le&longs;s part of Heaven, than a City is of the Earth, and yet innumerable of the&longs;e have been de&longs;troyed, &longs;o as that no mark of them hath remain'd.