Part 4

When we read Plutarch's criticism (Quæst. Plat. p. 1006 C) upon the word [Greek: i)llome/nên], we see that he puts to himself the question thus--"Does Plato in the Timæus conceive the earth as kept together and stationary--or as turning round and revolving, agreeably to the subsequent theory of Aristarchus and Seleukus?" Here we find that Plutarch conceives the alternative thus--Either the earth does not revolve at all, or it revolves as Aristarchus understood it. One or other of these two positions must have been laid down by Plato in the Timæus.--So we read in Plutarch. But the fact is, that Plato meant neither the one nor the other. The rotation of the earth round the solid cosmical axis, which he affirms in the Timæus--is a phenomenon utterly different from the rotation of the earth as a free body round the imaginary line called its own axis, which was the doctrine of Aristarchus.

When expositors in Plutarch's day, and since his day, enquired whether or not the Platonic Timæus affirmed the rotation of the earth, they meant to designate the rotation of the earth in the sense of Aristarchus, and in the sense in which modern astronomy understands that capital fact. Now speaking the language of modern astronomy, I think it certain that the rotation of the earth is _not_ to be found affirmed in the Platonic Timæus; and I agree with M. Boeckh when he says (Untersuch. p. 77), "Granting that Aristotle ascribed to Plato the doctrine of the rotation of the earth, he at least did not ascribe to him the doctrine as Gruppe assumes, and as now understood." As between Gruppe--who holds that the Platonic Timæus affirms the rotation of the earth, and that Aristotle ascribes it to him, in our sense of the words--and M. Boeckh, who denies this--I stand with the latter for the negative. But when M. Boeckh assumes that the only alternative doctrine is the immobility of the earth, and tries to show that this doctrine is proclaimed in the Platonic Timæus--nay, that no opposite doctrine _can_ be proclaimed, because the discourse expressly announces the rotation of the sidereal heaven in twenty-four hours--I am compelled to dissent from him as to the conclusion, and to deny the cogency of his proof. M. Boeckh has hardly asked himself the question, whether there was not some other sense in which Plato might have affirmed it in the Timæus. I have endeavoured to show that there was another sense; that there are good analogies in Plato to justify the belief that he intended to affirm the doctrine in that other sense; and that the comments of Aristotle--while thoroughly pertinent, if we thus understand the passage in the Timæus--become either irrelevant, dishonest, or absurd, if we construe the passage as signifying either what is maintained by M. Boeckh or what is maintained by Gruppe.

The eminent critics, whose opinions I here controvert, have been apparently misled by the superior astronomical acquirements of the present age, and have too hastily made the intellectual exigencies of their own minds a standard for all other minds, in different ages as well as in different states of cultivation. The question before us is, not what doctrines are scientifically true or scientifically compatible with each other, but what doctrines were affirmed or implied by Plato. In interpreting him, we are required to keep our minds independent of subsequent astronomical theories. We must look, first and chiefly, to what is said by Plato himself; next, if that be obscure, to the construction and comments of his contemporaries so far as they are before us. In no case is this more essential than in the doctrine of the rotation of the earth, which in the modern mind has risen to its proper rank in scientific importance, and has become connected with collateral consequences and associations foreign to the ideas of the ancient Pythagoreans, or Plato, or Aristotle. Unless we disengage ourselves from these more recent associations, we cannot properly understand the doctrine as it stands in the Platonic Timæus.

This doctrine, as I have endeavoured to explain it, leads to an instructive contrast between the cosmical theories of Plato (in the Timæus) and Aristotle.

Plato conceives the kosmos as one animated and intelligent being or god, composed of body and soul. Its body is moved and governed by its soul, which is fixed or rooted in the centre, but stretches to the circumference on all sides, as well as all round the exterior. It has a perpetual movement of circular rotation in the same unchanged place, which is the sort of movement most worthy of a rational and intelligent being. The revolutions of the exterior or sidereal sphere (Circle of the Same) depend on and are determined by the revolutions of the solid cylinder or axis, which traverses the kosmos in its whole diameter. Besides these, there are various interior spheres or circles (Circles of the Different), which rotate by distinct and variable impulses in a direction opposite to the sidereal sphere. This latter is so much more powerful than they, that it carries them all round with it; yet they make good, to a certain extent, their own special opposite movement, which causes their positions to be ever changing, and the whole system to be complicated. But the grand capital, uniform, overpowering, movement of the kosmos, consists in the revolution of the solid axis, which determines that of the exterior sidereal sphere. The impulse or stimulus to this movement comes from the cosmical soul, which has its root in the centre. Just at this point is situated the earth, "the oldest and most venerable of intra-kosmic deities," packed round the centre of the axis, and having for its function to guard and regulate those revolutions of the axis, and through them those of the outer sphere, on which the succession of day and night depends--as well as to nurse mankind.

In all this we see that the ruling principle and force of the kosmos ([Greek: to\ ê(gemoniko\n tou= ko/smou]) is made to dwell in and emanate from _its centre_.

When we come to Aristotle, we find that the ruling principle or force of the kosmos is placed, not in its centre, but in its circumference. He recognises no solid revolving axis traversing the whole diameter of the kosmos The interior of the kosmos is occupied by the four elements--earth, water, air, fire--neither of which can revolve except by violence or under the pressure of extraneous force. To each of them rectilinear motion is _natural_; earth moves naturally towards the centre--fire moves naturally towards the circumference, away from the centre. But the peripheral substance of the kosmos is radically distinct from the four elements: rotatory motion in a circle is _natural_ to it, and is the only variety of motion natural to it. That it is moved at all, it owes to a _primum movens immobile_ impelling it: but the two are coeternal, and the motion has neither beginning nor end. That when moved, its motion is rotatory and not rectilinear, it owes to its own nature. It rotates perpetually, through its own nature and inherent virtue, not by constraining pressure communicated from a centre or from a soul. If constraint were required--if there were any contrary tendency to be overcome--the revolving periphery would become fatigued, and would require periods of repose; but, since in revolving it only obeys its own peculiar nature, it persists for ever without knowing fatigue. This peripheral or fifth essence, perpetually revolving, is the divine, venerable, and commanding portion of the kosmos, more grand and honourable than the interior parts or the centre. Aristotle lays this down (De Coelo, ii. 13, p. 293, b. 10) in express antithesis to the Pythagoreans, who (like Plato) considered the centre as the point of grandeur and command, placing fire in the centre for that reason. The earth has no positive cosmical function in Aristotle; it occupies the centre because all its parts have a natural movement towards the centre: and it is unmoved because there _must be_ something in the centre which is always stationary, as a contrary or antithesis to the fifth essence or peripheral substance of the kosmos, which is in perpetual rotation by its own immutable nature.

I do not here go farther into the exposition of these ancient cosmical theories. I have adverted to Aristotle's doctrine only so far as was necessary to elucidate, by contrast, that which I believe to be the meaning of the Platonic Timæus about the rotation of the earth.

LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET, AND CHARING CROSS.

**************************************************************** Transcriber's Note

The text is based on versions made available by the Internet Archive.

For the Greek transcriptions the following conventions have been used: ) is for smooth breathing; ( for hard; + for diaeresis; / for acute accent; \ for grave; = for circumflex; | for iota subscript. ch is used for chi, ph for phi, ps for psi, th for theta; ê for eta and ô for omega; u is used for upsilon in all cases.

Corrections to the text, indicated with **

Text Correction Ti/ma/iô Ti/maio chore/ia chorei/a ou)/ranon ou)rano\n tetamenon tetame/non e)ndeiknutai e)ndei/knutai] forge force Tima/iô| Timai/ô| gegraptai ge/graptai] e(ilei=sthai ei(lei=sthai e)/pi\ e)pi\ a)utê=s au)tê=s