Part 1

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.

The right of Translation is reserved.

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

EXAMINATION OF THE THREE FOLLOWING QUESTIONS:--

1. WHETHER THE DOCTRINE OF THE EARTH'S ROTATION IS AFFIRMED OR IMPLIED IN THE PLATONIC TIMÆUS?

2. IF AFFIRMED OR IMPLIED, IN WHAT SENSE?

3. WHAT IS THE COSMICAL FUNCTION WHICH PLATO ASSIGNS TO THE EARTH IN THE TIMÆUS?

PREFACE.

The following paper was originally intended as an explanatory note on the Platonic Timæus, 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, Timæus, p. 40 B, we read the following words--[Greek: Gê=n de\ tropho\n me\n ê(mete/ran, ei(llome/nên de\ peri\ to\n dia\ panto\s po/lon tetame/non phu/laka kai\ dêmiourgo\n nukto/s te kai\ ê(me/ras e)mêchanê/sato, prô/tên kai\ presbuta/tên theô=n, o(/soi e)nto\s ou)ra/nou gego/nasi.] I give the text as it stands in Stallbaum's edition.

The obscurity of this passage is amply attested by the numerous differences of opinion to which it has given rise, both in ancient and in modern times. Various contemporaries of Plato ([Greek: e)/nioi]--Aristot. De Coelo, II. 13, p. 293 b. 30) understood it as asserting or implying the rotatory movement of the earth in the centre of the Kosmos, and adhered to this doctrine as their own. Aristotle himself alludes to these contemporaries without naming them, and adopts their interpretation of the passage; but dissents from the doctrine, and proceeds to impugn it by arguments. Cicero mentions (Academic II. 39) that there were persons who believed Plato to have indicated the same doctrine obscurely, in his Timaeus: this passage must undoubtedly be meant. Plutarch devotes a critical chapter to the enquiry, what was Plato's real doctrine as to the cosmical function of the earth--its movement or rest (Quaestion. Platonic. VII. 3, p. 1006.)

There exists a treatise, in Doric dialect, entitled [Greek: Ti/maio** tô= Lo/krô Peri\ Psucha=s Ko/smô kai\ Phu/sios], 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 [Greek: i)llome/nên] or [Greek: ei(loume/nên].

Alexander of Aphrodisias (as we learn from Simplikius ad Aristot. De Coelo, fol. 126) followed the construction of Plato given by Aristotle. "It was improbable (he said) that Aristotle could be ignorant either what the word signified, or what was Plato's purpose" ([Greek: a)lla\ tô=| A)ristote/lei, phêsi\n, ou(/tô le/gonti i)/llesthai, ou)k eu)/logon a)ntile/gein; ô(s a)lêthô=s ga\r ou)/te tê=s le/xeôs to\ sêmaino/menon ei)ko\s ê)=n a)gnoei=n au)to\n, ou)/te to\n Pla/tônos skopo/n.] This passage is not given in the Scholia of Brandis). Alexander therefore construed [Greek: i)llome/nên] as meaning or implying rotatory movement, though in so doing he perverted (so Simplikius says) the true meaning to make it consonant with his own suppositions.

Proklus maintains that Aristotle has interpreted the passage erroneously,--that [Greek: i)llome/nên] is equivalent to [Greek: sphiggome/nên] or [Greek: xunechome/nên]--and that Plato intends by it to affirm the earth as at rest in the centre of the Kosmos (ad Timaeum, Book iv., p. 681 ed. Schneider). Simplikius himself is greatly perplexed, and scarcely ventures to give a positive opinion of his own. On the whole, he inclines to believe that [Greek: i)llome/nên] 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 (ad Aristot. De Coelo, p. 126).

Both Proklus and Simplikius, we must recollect, believed in the genuineness of the Doric treatise ascribed to Timaeus Locrus. Reasoning upon this basis, they of course saw, that if Aristotle had correctly interpreted Plato, Plato himself must have interpreted incorrectly the doctrine of Timaeus. They had to ascribe wrong construction either to Plato or to Aristotle: and they could not bear to ascribe it to Plato.

Alkinous, in his Eisagôge (c. 15) gives the same interpretation as Proklus. But it is remarkable that in his paraphrase of the Platonic words, he calls the earth [Greek: ê(me/ras phu/lax kai\ nukto/s]: omitting the significant epithet [Greek: dêmiourgo/s].

In regard to modern comments upon the same disputed point, I need only mention (besides those of M. Cousin, in the notes upon his translation of the 'Timæus', and of Martin in his 'Études sur le Timée') the elaborate discussion which it has received in the two recent Dissertations 'Ueber die kosmischen Systeme der Griechen,' by Gruppe and Boeckh. Gruppe has endeavoured, upon the evidence of this passage, supported by other collateral proofs, to show that Plato, towards the close of his life, arrived at a belief, first, in the rotation of the earth round its own axis, next, at the double movement of the earth, both rotation and translation, round the sun as a centre (that is, the heliocentric or Copernican system): that Plato was the first to make this discovery, but that he was compelled to announce it in terms intentionally equivocal and obscure, for fear of offending the religious sentiments of his contemporaries ('Die kosmischen Systeme der Griechen, von O. F. Gruppe,' Berlin, 1851). To this dissertation M. Boeckh--the oldest as well as the ablest of all living philologists--has composed an elaborate reply, with his usual fulness of illustrative matter and sobriety of inference. Opinions previously delivered by him (in his early treatises on the Platonic and Pythagoreian philosophy) had been called in question by Gruppe: he has now re-asserted them and defended them at length, maintaining that Plato always held the earth to be stationary and the sidereal sphere rotatory--and answering or extenuating the arguments which point to an opposite conclusion ('Untersuchungen über das kosmische System des Platon, von August Boeckh,' Berlin, 1852).

Gruppe has failed in his purpose of proving that Plato adopted either of the two above-mentioned doctrines--either the rotation of the earth round its own axis, or the translation of the earth round the sun as a centre. On both these points I concur with Boeckh in the negative view. But though I go along with his reply as to its negative results, I cannot think it satisfactory in its positive aspect as an exposition of the doctrine proclaimed in the Platonic Timæus: nor can I admit that the main argument of M. Boeckh's treatise is sufficient to support the inference which he rests upon it. Moreover, he appears to me to set aside or explain away too lightly the authority of Aristotle. I agree with Alexander of Aphrodisias and with Gruppe who follows him, in pronouncing Aristotle to be a good witness, when he declares what were the doctrines proclaimed in the Platonic Timæus; though I think that Gruppe has not accurately interpreted either Timæus or Aristotle.

The capital argument of Boeckh is as follows: "The Platonic Timæus affirms, in express and unequivocal terms, the rotation of the outer celestial sphere (the sidereal sphere or Aplanes) in twenty-four hours, as bringing about and determining the succession of day and night. Whoever believes this cannot at the same time believe that the earth revolves round its own axis in twenty-four hours, and that the succession of day and night is determined thereby. The one of these two affirmations excludes the other; and, as the first of the two is proclaimed, beyond all possibility of doubt, in the Platonic Timæus, so we may be sure that the second of the two cannot be proclaimed in that same discourse. If any passage therein seems to countenance it, we must look for some other mode of interpreting the passage."

This is the main argument of M. Boeckh, and also of Messrs. Cousin and Martin. The latter protests against the idea of imputing to Plato "un mélange monstrueux de deux systêmes incompatibles" (Études sur le Timée, vol. ii. p. 86-88).

As applied to any person educated in the modern astronomy, the argument is irresistible. But is it equally irresistible when applied to Plato and to Plato's time? I think not. The incompatibility which appears so glaring at present, did not suggest itself to him or to his contemporaries. To prove this we have only to look at the reasoning of Aristotle, who (in the treatise De Coelo, ii. 13-14, p. 293. b. 30, 296. a. 25) notices and controverts the doctrine of the rotation of the earth, with express reference to the followers of the Platonic Timæus--and who (if we follow the view of Martin) imputes this doctrine with wilful falsehood to Plato, for the purpose of contemptuously refuting it "pour se donner le plaisir de la réfuter avec dédain." Granting the view of M. Boeckh (still more that of Martin) to be correct, we should find Aristotle arguing thus:--"Plato affirms the diurnal rotation of the earth round the centre of the cosmical axis. This is both incredible, and incompatible with his own distinct affirmation that the sidereal sphere revolves in twenty-four hours. It is a glaring inconsistency that the same author should affirm both the one and the other." Such would have been Aristotle's reasoning, on the hypothesis which I am considering; but when we turn to his treatise we find that he does not employ this argument at all. He contests the alleged rotation of the earth upon totally different arguments--chiefly on the ground that rotatory motion is not natural to the earth, that the kind of motion natural to the earth is rectilineal, towards the centre; and he adds various corollaries flowing from this doctrine which I shall not now consider. At the close of his refutation, he states in general terms that the celestial appearances, as observed by scientific men, coincided with his doctrine.