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 Cœlo, 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.

Hence we may plainly see that Aristotle probably did not see the incompatibility, supposed to be so glaring, upon which M. Boeckh’s argument is founded. To say the least, even if he saw it, he did not consider it as glaring and decisive. He would have put it in the foreground of his refutation, if he had detected the gross contradiction upon which M. Boeckh insists. But Aristotle does not stand alone in this dulness of vision. Among the various commentators, ancient and modern, who follow him, discussing the question now before us, not one takes notice of M. Boeckh’s argument. He himself certifies to us this fact, claiming the argument as his own, and expressing his astonishment that all the previous critics had passed it over, though employing other reasons much weaker to prove the same point. We read in M. Boeckh’s second ‘Commentatio de Platonico Systemate Cœlestium Globorum et de Verâ Indole Astronomiæ Philolaicæ,’ Heidelberg, 1810, p. 9, the following words:—

“Non moveri tellurem, Proclus et Simplicius ostendunt ex Phædone. Parum firmum tamen argumentum est ex Phædone ductum ad interpretandum Timæi locum: nec melius alterum, quod Locrus Timæus, quem Plato sequi putabatur, terram stare affirmat: quia, ut nuper explicuimus, non Plato ex Locro, sed personatus Locrus ex Platone, sua compilavit. At omnium firmissionum et certissimum argumentum ex ipso nostro dialogo sumptum, adhuc, quod jure mirere, nemo reperit. Etenim, quum, paulo supra, orbem stellarum fixarum, quem Græci ἀπλανῆ appellant, dextrorsum ferri quotidiano motu Plato statuebat, non poterat ullum terræ motum admittere; quia, qui hunc admittit, illum non tollere non potest.” (This passage appears again cited by M. Boeckh himself in his more recent dissertation ‘Untersuchungen über das kosmische System des Platon,’ p. 11). The writers named (p. 7) as having discussed the question, omitting or disregarding this most cogent argument, are names extending from Aristotle down to Ruhnken and Ideler.

It is honourable to the penetration of M. Boeckh that he should have pointed out, what so many previous critics had overlooked, that these two opinions are scientifically incompatible. He wonders, and there may be good ground for wondering, how it happened that none of these previous writers were aware of the incompatibility. But the fact that it did not occur to them, is not the less certain, and is of the greatest moment in reference to the question now under debate; for we are not now inquiring what is or is not scientifically true or consistent, but what were the opinions of Plato. M. Boeckh has called our attention to the fact, that these two opinions are incompatible; but can we safely assume that Plato must have perceived such incompatibility between them? Surely not. The Pythagoreans of his day did not perceive it; their cosmical system included both the revolution of the earth and the revolution of the sidereal sphere round the central fire, ten revolving bodies in all (Aristotel. Metaphysic. i. 35, p. 96 a. 10. De Cœlo, ii. 13, p. 293 b. 21). They were not aware that the revolutions of the one annulled those of the other as to effect, and that their system thus involved the two contradictory articles, or “mélange monstrueux,” of which Martin speaks so disdainfully. Nay, more, their opponent, Aristotle, while producing other arguments against them, never points out the contradiction. Since it did not occur to them, we can have no greater difficulty in believing that neither did it occur to Plato. Indeed, the wonder would rather be if Plato had seen an astronomical