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PLATO'S DOCTRINE

RESPECTING THE

ROTATION OF THE EARTH,

AND

ARISTOTLE'S COMMENT UPON THAT DOCTRINE.

BY GEORGE GROTE, ESQ.

LONDON: JOHN MURRAY, ALBEMARLE STREET. 1860.

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

EXAMINATION OF THE THREE FOLLOWING QUESTIONS:--

PREFACE

The following paper was originally intended as an explanatory note on the Platonic Timaeus, in the work which I am now preparing on Plato and Aristotle. Interpreting, differently from others, the much debated passage in which Plato describes the cosmical function of the Earth, I found it indispensable to give my reasons for this new view. But I soon discovered that those reasons could not be comprised within the limits of a note. Accordingly I here publish them in a separate Dissertation. The manner in which the Earth's rotation was conceived, illustrates the scientific character of the Platonic and Aristotelian age, as contrasted with the subsequent development and improvement of astronomy.

PLATO--ON THE EARTH'S ROTATION.

In Plato, Timaeus, p. 40 B, we read the following words-- I give the text as it stands in Stallbaum's edition.

There exists a treatise, in Doric dialect, entitled , which is usually published along with the works of Plato. This treatise was supposed in ancient times to be a genuine production of the Lokrian Timaeus, whom Plato introduces as his spokesman in the dialogue so called. As such, it was considered to be of much authority in settling questions of interpretation as to the Platonic Timaeus. But modern critics hold, I believe unanimously, that it is the work of some later Pythagorean or Platonist, excerpted or copied from the Platonic Timaeus. This treatise represents the earth as being in the centre and at rest. But its language, besides being dark and metaphorical, departs widely from the phraseology of the Platonic Timaeus: especially in this--that it makes no mention of the cosmical axis, nor of the word or This passage is not given in the Scholia of Brandis). Alexander therefore construed as meaning or implying rotatory movement, though in so doing he perverted the true meaning to make it consonant with his own suppositions.

Proklus maintains that Aristotle has interpreted the passage erroneously,--that is equivalent to or --and that Plato intends by it to affirm the earth as at rest in the centre of the Kosmos . Simplikius himself is greatly perplexed, and scarcely ventures to give a positive opinion of his own. On the whole, he inclines to believe that might possibly be understood, by superficial readers, so as to signify rotation, though such is not its proper and natural sense: that some Platonists did so misunderstand it: and that Aristotle accepted their sense for the sake of the argument, without intending himself to countenance it .

It appears to me, therefore, that M. Boeckh has not satisfactorily made good his point--"Plato cannot have believed in the diurnal rotation of the earth, because he unquestionably believed in the rotation of the sidereal sphere as causing the succession of night and day." For, though the two doctrines really are incompatible, yet the critics antecedent to M. Boeckh took no notice of such incompatibility. We cannot presume that Plato saw what Aristotle and other authors, even many writing under a more highly developed astronomy, did not see. We ought rather, I think, to presume the contrary, unless Plato's words distinctly attest that he did see farther than his successors.

Now let us examine what Plato's words do attest:--)

I explain these words as follows:--

Here we see exactly the position of Plato in regard to the rotation of the earth. He does not affirm it in express terms, but he affirms what implies it. For when he says that the earth is packed, or fastened close round the cosmical axis, he conveys to us by implication the knowledge of another and distinct fact--that the earth and the cosmical axis must either revolve together or remain stationary together--that the earth must either revolve along with the axis or arrest the revolutions of the axis. It is manifest that Plato does not mean the revolutions of the axis of the kosmos to be arrested: they are absolutely essential to the scheme of the Timaeus--they are the grand motive-agency of the kosmos. He must, therefore, mean to imply that the earth revolves along with and around the cosmical axis. And thus the word , according to Buttmann's doctrine, becomes accidentally conjoined, through the specialities of this case, with an accessory idea of rotation or revolution; though that idea is foreign to its constant and natural meaning.

The passages are two, both of them in the second book De Coelo; one in cap. 13, the other in cap. 14 .

M. Boeckh, in a discussion of some length , maintains the opinion that the reading in the first passage of Aristotle is incorrect; that the two words ought to stand in the first as they do in the second,--as he thinks that they stood in the copy of Simplikius: that Aristotle only made reference to Plato with a view to the peculiar word , and not to the general doctrine of the rotation of the earth: that he comments upon this doctrine as held by others, but not by Plato--who was known by everyone not to hold it. M. Boeckh gives this only as a conjecture, and I cannot regard his arguments in support of it as convincing. But even if he had convinced me that were the true reading in the first passage, as well as in the second, I should merely say that Aristotle had not thought himself precluded by the reference to the Timaeus from bringing out into explicit enunciation what the Platonists whom he had in view knew to be implied and intended by the passage. This indeed is a loose mode of citation, which I shall not ascribe to Aristotle without good evidence. In the present case such evidence appears to me wanting.

Perhaps M. Martin might say--"The contradiction exists; but Aristotle was not sharpsighted enough to perceive it; otherwise he would have advanced it." I am quite of this opinion. If Aristotle had perceived the contradiction, he would have brought it forward as the strongest point in his controversy. His silence is to me a proof that he did not perceive it. But this is a part of my case against M. Martin. I believe that Plato admitted both the two contradictory doctrines without perceiving the contradiction; and it is a strong presumption in favour of this view that Aristotle equally failed to perceive it--though in a case where, according to M. Martin, he did not scruple to resort to dishonest artifice.

It appears to me that the difficulties and anomalies, in which we are involved from supposing that Aristotle either misunderstood or perverted the meaning of Plato--are far graver than those which would arise from admitting that Plato advanced a complicated theory involving two contradictory propositions, in the same dialogue, without perceiving the contradiction; more especially when the like failure of perception is indisputably ascribable to Aristotle--upon every view of the case.

M. Cousin maintains the same interpretation of the Platonic passage as Boeckh and Martin, and defends it by a note on his translation of the Timaeus . The five arguments which he produces are considered both by himself and by Martin to be unanswerable. As he puts them with great neatness and terseness, I here bestow upon them a separate examination.

The terms of this fourth argument, if literally construed, would imply that Plato had devised a complete and satisfactory astronomical theory. I pass over this point, and construe them as M. Cousin probably intended: his argument will then stand thus--"The movement of the earth does not add anything to Plato's power of explaining astronomical appearances; therefore Plato had no motive to suggest a movement of the earth."

M. Cousin adds, as a sixth argument:--

"On peut ajouter ? ces raisons que Platon aurait n?cessairement insist? sur le mouvement de la terre, s'il l'avait admis; et que ce point ?toit trop controvers? de son temps et trop important en lui-m?me, pour qu'il ne f?t que l'indiquer en se servant d'une expression ?quivoque."

In the first place, granting Plato to have believed in the motion of the earth, can we also assume that he would necessarily have asserted it with distinctness and emphasis, as M. Cousin contends? I think not. Gruppe maintains exactly the contrary; telling us that Plato's language was intentionally obscure and equivocal--from fear of putting himself in open conflict with the pious and orthodox sentiment prevalent around him. I do not carry this part of the case so far as Gruppe, but I admit that it rests upon a foundation of reality. When we read how the motion of the earth, as affirmed by Aristarchus of Samos , was afterwards denounced as glaring impiety, we understand the atmosphere of religious opinion with which Plato was surrounded. And we also perceive that he might have reasons for preferring to indicate an astronomical heresy in terms suitable for philosophical hearers, rather than to proclaim it in such emphatic unequivocal words, as might be quoted by some future Mel?tus in case of an indictment before the Dikasts.

We must remember that Plato had been actually present at the trial of Sokrates. He had heard the stress laid by the accusers on astronomical heresies, analogous to those of Anaxagoras, which they imputed to Sokrates--and the pains taken by the latter to deny that he held such opinions . The impression left by such a scene on Plato's mind was not likely to pass away: nor can we be surprised that he preferred to use propositions which involved and implied, rather than those which directly and undisguisedly asserted, the heretical doctrine of the earth's rotation. That his phraseology, however indirect, was perfectly understood by contemporary philosophers, both assentient and dissentient, as embodying his belief in the doctrine--is attested by the two passages of Aristotle.

Upon these reasons alone I should dissent from M. Cousin's sixth argument. But I have other reasons besides. He rests it upon the two allegations that the doctrine of the earth's motion was the subject of much controversial debate in Plato's time, and of great importance in itself. Now the first of these two allegations can hardly be proved, as to the time of Plato; for Aristotle, when he is maintaining the earth's immobility, does not specify any other opponents than the Pythagoreians and the followers of the Platonic Timaeus. And the second allegation I believe to be unfounded, speaking with reference to the Platonic Timaeus. In the cosmical system therein embodied, the rotation of the earth round the cosmical axis, though a real part of the system, was in itself a fact of no importance, and determining no results. The capital fact of the system was the position and function of the earth, packed close round the centre of the cosmical axis, and regulating the revolutions of that axis. Plato had no motive to bring prominently forward the circumstance that the earth revolved itself along with the cosmical axis, which circumstance was only an incidental accompaniment.

Proklus argues that because the earth is mentioned by Plato in the Phaedon as stationary in the centre of the heaven, we cannot imagine Plato to affirm its rotation in the Timaeus. I agree with M. Boeckh in thinking this argument inconclusive; all the more, because, in the Phaedon, not a word is said either about the axis of the kosmos, or about the rotation of the kosmos; all that Sokrates professes to give is . No cosmical system or theory is propounded in that dialogue.

When we turn to the Phaedrus, we find that, in its highly poetical description, the rotation of the heaven occupies a prominent place. The internal circumference of the heavenly sphere, as well as its external circumference or back , are mentioned; also its periodical rotations, during which the gods are carried round on the back of the heaven, and contemplate the eternal Ideas occupying the super-celestial space , or the plain of truth. But the purpose of this poetical representation appears to be metaphysical and intellectual, to illustrate the antithesis presented by the world of Ideas and Truth on one side--against that of sense and appearances on the other. Astronomically and cosmically considered, no intelligible meaning is conveyed. Nor can we even determine whether the rotations of the heaven, alluded to in the Phaedrus, are intended to be diurnal or not; I incline to believe not . Lastly, nothing is said in the Phaedrus about the cosmical axis; and it is upon this that the rotations of the earth intimated in the Timaeus depend.

The two meanings here indicated are undoubtedly distinct and independent. But they are not for that reason contradictory and incompatible. It has been the mistake of critics to conceive them as thus incompatible; so that if one of the two were admitted, the other must be rejected. I have endeavoured to show that this is not universally true, and that there are certain circumstances in which the two meanings not only may come together, but must come together. Such is the case when we revert to Plato's conception of the cosmical axis as a solid revolving cylinder. That which is packed or fastened around the cylinder must revolve around it, and along with it.

Both M. Boeckh and Gruppe assume the incompatibility of the two meanings; and we find the same assumption in Plutarch's criticisms on the Timaeus , where he discusses what Plato means by ; and in what sense the earth as well as the moon can be reckoned as . Plutarch inquires how it is possible that the earth, if stationary and at rest, can be characterised as "among the instruments of time;" and he explains it by saying that this is true in the same sense as we call a gnomon or sun-dial an instrument of time, because, though itself never moves, it marks the successive movements of the shadow. This explanation might be admissible for the phrase ; but I cannot think that the immobility of the earth can be made compatible with the attribute which Plato bestows upon it of being , we see that he puts to himself the question thus--"Does Plato in the Timaeus 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 Timaeus.--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 Timaeus--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.

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 Timaeus.

This doctrine, as I have endeavoured to explain it, leads to an instructive contrast between the cosmical theories of Plato 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 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 , 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.

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 Timaeus about the rotation of the earth.

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

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