An entire body of philosophy according to the principles of the famous Renate Des Cartes in three books, (I) the institution ... (II) the history of nature ... (III) a dissertation of the want of sense and knowledge in brute animals ... / written originally in Latin by the learned Anthony Le Grand ; now carefully translated from the last corrections, alterations, and large additions of the author, never yet published ... by Richard Blome.

CHAP. VIII. Of the Ptolomaick, Copernican, and Tycho∣nick Systems of the World.

I. What a System is, and how many there are. A System in Natural Philosophy is that, whereby a thing acts after a certain man∣ner, by virtue of its Composition, and those Dis∣positions which constitute its Nature. Thus we call the System of the World, the Order or Disposi∣tion wherein we conceive, that all we see in the World is performed, by supposing it to be com∣pos'd of certain Parts, the Nature and Connexion whereof is such, that thence results whatsoever is, or is done in it. Amongst the Systems of the World, invented by Astronomers, there are Three more famous than the rest, viz. those of Ptolomy, Copernicus, and Tycho Brahe, to which all the rest that have been invented by the Ancients may be referr'd.

II. The Ptolo∣maick System. PTOLOMY placeth the Globe of Earth and Water in the Center of the World, and suppo∣seth it destitute of all motion. Next to the Earth, he placeth the Air mingled with Vapours and Exha∣lations, * 1.1which raising it self only a few Miles above the Earth, is called the Atmosphere. Next below the Moon he placeth his Element of Fire; the several Spaces above which he divides into Eleven Spheres, in the first Seven whereof he ranks the Planets: In the first ☽, the Moon; in the second ☿, Mercury; in the third ♀, Venus; in the fourth ☉, the Sun; in the fifth ♂, Mars; in the sixth ♃, Jupiter; in the seventh ♄, Saturn; which he calls Wandring Stars: Not that they wander at Random; but because they are carried with an unequal motion within the Zodiack, so as not to keep the same Distance from one another, if compar'd with the fix'd Stars. In the Eighth Sphere he placeth the Firmament, in which the fix'd Stars are supposed to be fastned.

After these follow two other Spheres, which he calls Crystalline, or the Heavens of Libration and Trepidation; the first Moving from the East to the West, the other from the North to the South. The Eleventh and highest Sphere he calls the Pri∣mum Mobile, or First moved. This Description of the World is by the Common People generally approved and maintain'd; who look upon the Heaven as a Vaulted Roof, equally distant from us, who are as in the Center and suppose all the Stars that appear in it, to be in the said Circumference of the World.

III. The System of Coper∣nicus. NICOLAUS COPERNICUS, a Physician of Thorn, and Canon of Frassenburg, who flourish'd not much above an hundred years since, introduced another System in Imitation of the Pythagoreans, who attributed a motion to the Earth, and plac'd the Sun as the Soul of the * 1.2World, in the Center of it; and consequently assigns the same place to the Earth, which Ptolomy allows the Sun, that is, betwixt the Planets Venus and Mars. The Earth, according to Copernicus, hath two motions; the one Diurnal, which in 24 Hours space is performed about its own Axis, from West to East; which Motion makes Days and Nights, as shall be said hereafter. And this Motion performs the same Service, which the Primum mobile doth in the Ptolomaick System, to wit, by effecting that all the Stars seem to move from East to West; much in the same manner as a Ship, which sailing from the Shoar, or towards it, makes the Shoar it self seem, as if it drew near, or withdrew from the Ship. The other Motion of the Earth, is its Annual motion, by which she is carried about the Sun, from the West also to the East, according to the Succession of the Signs of the Zodiack; by which means, the Sun which stands immovable in the Center of the World, doth seem to run through those Signs, tho' indeed it is the Earth only that truly doth so. And whereas the Space that is between Mars and Venus, is large enough for the Moon to be carried round between them, she accordingly performs there two Motions, the one Monthly, wherewith she is whirl'd about the Center of the Earth, and appears in her several Changes; the other Yearly, whereby (together with the Earth) she goes round the Sun.

Wherefore, according to the Copernican System, the Sun is placed in the Center of the World im∣movable. Tho' this hinders not, but that it may be carried round about its own Axis within the space of 27 days, which that it is, appears by the turning round of its Spots, discovered by the Tele∣scope. Next to the Sun, Mercury is whirl'd about; in the second place, Venus; in the third, the Earth, together with the Moon its Attendant; in the fourth, Mars; in the fifth, Jupiter; and in the last, Saturn. After which follows the Region of the fix'd Stars, so called, not because they are without all motion, but because they do not wander up and down like the Planets, but continue in their own places, and keep the same distance from one another, as will be shewed in the XXth Chapter of this Part.

IV. The System of Ty•••••• Brahe. Besides these two Systems, a Third hath been contrived by TYCHO BRAHE, which par∣takes of both the foregoing Systems. For as to the Digestion of the Parts of the World, it agrees with the Coper••ican, save only in this, that it con∣stitutes * 1.3the Earth to be the Center of the Firma∣ment, and accordingly makes the Moon and Sun to run round it. Thus in explaining the seeming motion of the Heaven, which seems to be performed

in 24 Hours, he follows Ptolomy, and supposeth the Earth to stand immoved in the Center, and the whole Heaven to be carried round it, from East to West, by the Force of the Primum Mobile. But in explaining the Appearances of the Planets, he agrees with Copernicus; making Mercury and Ve∣nus to be carried round nearest to the Sun, as their Center; but Mars, Jupiter and Saturn at a far∣ther distance; and in the middle Space placeth the Earth, with the Moon that is carried round her, in the same time that Copernicus assigns to it. The Tychonick System has this peculiar to it self, that the Planets, which perform their own motions about the Sun, are whirl'd about by it, so as that Mercury and Venue, in their Turnings round about the Sun, do never take in the Earth, as Mars, Jupiter, and Saturn do. So that as Gassendus ob∣serves, If instead of the Sun's whirling about together with Mercury and Venus, who exclude the Earth from the compass they take, and with Mars, Jupiter and Saturn enclosing it, the Earth had been supposed to be whirl'd about with the Moon, comprehending in its compass Venus and Mercury, but comprehended within the compass of Mars, Jupiter and Saturn, it would come to the ••••me thing; and Tycho's System would appear to be nothing else but the Copernican invert∣ed.

V. Ptolomy's System re∣jected. Having given this brief Description of these three Systems, we are next to examine which of them appears the Truest. For seeing that they all differ, and that the Structure or Disposition of the Parts of the World is but one only, we must reject two of them as false, and choose the third us the truest. And tho' we should suppose nothing of Contradiction to be found in any of these Thr••e, yet ought we to pitch upon that as the best, which appears the most simple, and supposeth least particulars.

VI. Many ••••••ngs are 〈◊〉〈◊〉 in ••••e Ptolo∣maick Sy∣stem, as ••••ing con∣trary to Experience. Wherefore we cannot admit of the Ptolomaick System, as being contrary both to Reason and Expe∣rience: To Experience first, with regard to the appearances of Venus and Mercury, seeing it is evident that these Planets are not always whirl'd about on this side of the Sun, as Ptolomy supposeth, but sometimes appear above, and sometimes be∣neath, yea, and sometimes also side-ways to it; so as that sometimes they are nearer to, and at other times they are further from us than the Sun. For this Cause Copernicus took occasion from the various appearance of Mars, to assign motion to the Earth. For he perceiving that Mars, whilst he is op∣posite to the Sun, appears much greater; and that he grows less, as he nearer approacheth to it, could not attribute this change to any thing better, than to the Circumrotation of the Earth: According to which, it was necessary for Mars to appear biggest, when the Earth moves nearest to him; and least, when the Earth leaves him on the other side of the Sun.

Secondly, Pursuant to this System, no Reason can be given why Mars, Jupiter and Saturn are always in the lower part of their Epicycles, when they are Retrograde. Whence it is that the Moon doth always turn the same part of her Body to∣wards us: Why Saturn appears in a various shape to us, sometimes Oval, and at others Round, when beheld through a Prospective.

Thir••y, This Hypothesis doth not explain the contrary Motions, whereby the Stars at the same time seem to move from East to West, and from West to East.

Fourthly, Neither can the rise of Comets, nor their motions, be solved, as long as we suppose the Heavens to be solid, as he doth.

Fifthly, According to this Hypothesis we cannot give any account, how the Spots about the Sun are generated, and afterwards dissipated; nor how they can perform their Circuits about the Sun.

VII. This Hyo∣thesis is likewise contrary to Reason. This System is also contrary to Reason, by allowing the motions of Trepidation and Libra∣tion to the Crystalline Heavens. For what is more misbecoming a Philosopher, than for the extricating of a lesser Change, to admit a far greater? For a Body that is carried towards one Point, tho' by an uneven motion, questionless doth not undergo so great a Change, as another, which is also carried towards one Point, and suddenly re∣bounds to the opposite Point. To this may be added, that it was in vain that the Ancients had recourse to this motion, for the explaining of the Equal progress of the fix'd Stars; since the most exact Astronomers frequently Experience, that what they deduce thence by their Computations, doth not correspond with the Phaenomena. Besides, the Motion of the Heavenly Orbs will be swifter than can be competent to such vast Bodies, and more especially to the Brittle Crystalline Spheres; for the utmost Sphere of the World must be whirl'd about in 24 Hours. Moreover, what is more im∣probable than that the Primum Mobile should have the force to carry round with it all the Inferiour Orbs, from East to West; and yet that the Earth, which is included in them, should remain un∣mov'd? When yet, according to Ptolomy, the Earth is altogether Passive, and is encompass'd with the subtil Matter. These Absurdities are sufficient to make us reject this Ptolomaick Hypo∣thesis.

VIII. The Tycho∣nick Sy∣stem also hath its Errors. Tho' the Tychonick Hypothesis seem more pro∣bable than the Ptolomaick, forasmuch as it gives an account of the Inequality and Diversity of the Coelestial Appearances, yet is it not without its obscurity and defects. For it seems in a manner to disjoynt the whole System of the World, foras∣much as whilst the Sun (the Center of Five of the Planets) whirls about the Earth in its Annual mo∣tion, this his Annual motion is entangled with the proper motions of the several Planets; for the ex∣plaining whereof he is fain to make use of a Circle, describ'd from the Suns Center with two Epicycles; whereas the structure of the World, is without doubt very far from any intricacy or confusion, and allows every Planet a sufficient Space to run its Course in.

IX. And is to rejected, as well as the Ptolo∣maick. Besides, this System h••th several other Defects for which it is to be rejected, as well as the Ptolo∣maick. For tho' it admits of less Suppositions for explication of the Motion of the Planets, and gives a plausible account of the Appearances of Venus; yet it cannot be deny'd, but that it requireth some∣thing, which the Mind of Man can hardly assent to, in that it supposeth that Motion, whereby the Mass, consisting of the Heavens and Planets, in Twelve Months time, moves towards all parts of the Firmament. For tho' we should admit, that it had been put into such a motion by the Author of Nature, at the beginning of the Creation; yet

withal we must suppose, that according to the Laws of Nature, which GOD himself hath esta∣blished, the said Motion, in success of Time, must be diminished, and at last cease altogether; since (according to the same) it must have been com∣municated to the Heavenly matter, which the foresaid Mass, to which BRAHE assigns this Motion, drives from those Parts to which it tends.

X. The Coper∣nican Sy∣stem is to be preferr'd before the two former. It remains therefore, that we only admit of the Copernican System, as being both more plain and simple than the two foregoing, and solving the Phaenomena of the Heaven the best of the three. But forasmuch as Des Cartes professeth himself to dissent from COPERNICUS and TYCHO as to the Motion of the Earth, which he denies with more Truth than TYCHO, and with more curio∣sity than COPERNICUS, we intend last of all to propound his Scheme, as the only true one.

Notes

• * 1.1

  Figure 16.
• * 1.2

  Figure 17.
• * 1.3

  Figure 18.