Note 25 — Chapter V · LIFE OF PLATO.

Respecting Eudoxus, see Diog. L. viii. 86-91. As the life of Eudoxus probably extended from about 406-353 B.C., his first visit to Athens would be about 383 B.C., some three years after Plato commenced his school. Strabo (xvii. 806), when he visited Heliopolis in Egypt, was shown by the guides certain cells or chambers which were said to have been occupied by Plato and Eudoxus, and was assured that the two had passed thirteen years together in Egypt. This account deserves no credit. Plato and Eudoxus visited Egypt, but not together, and neither of them for so long as thirteen years. Eudoxus stayed there sixteen months (Diog. L. viii. 87). Simplikius, Schol. ad Aristot. De Cœlo, p. 497, 498, ed. Brandis, 498, a. 45. Καὶ πρῶτος τῶν Ἑλλήνων Εὔδοξος ὁ Κνίδιος. ὡς Εὔδημός τε ἐν τῷ δευτέρῳ τῆς Ἀστρολογικῆς Ἰστορίας ἀπεμνημόνευσε καὶ Σωσιγένης παρὰ Εὐδήμου τοῦτο λαβὼν, ἅψασθαι λέγεται τῶν τοιούτων ὑποθέσεων· Πλάτωνος, ὡς φησι Σωσιγένης, πρόβλημα τοῦτο ποιησαμένου τοῖς περὶ ταῦτα ἐσπουδακόσι — τίνων ὑποτεθείσων ὁμαλῶν καὶ τεταγμένων κινήσεων διασωθῇ τὰ περὶ τὰς κινήσεις τῶν πλανωμένων φαινόμενα. The Scholion of Simplikius, which follows at great length, is exceedingly interesting and valuable, in regard to the astronomical theory of Eudoxus, with the modifications introduced into it by Kallippus, Aristotle, and others. All the share in it which is claimed for Plato, is, that he described in clear language the problem to be solved: and even that share depends simply upon the statement of the Alexandrine Sosigenes (contemporary of Julius Cæsar), not upon the statement of Eudemus. At least the language of Simplikius affirms, that Sosigenes copied from Eudemus the fact, that Eudoxus was the first Greek who proposed a systematic astronomical hypothesis to explain the motions of the planets — (παρ’ Εὐδήμου τοῦτο λαβών) not the circumstance, that Plato propounded the problem afterwards mentioned. From whom Sosigenes derived this last information, is not indicated. About his time, various fictions had gained credit in Egypt respecting the connection of Plato with Eudoxus, as we may see by the story of Strabo above cited. If Plato impressed upon others that which is here ascribed to him, he must have done so in conversation or oral discourse — for there is nothing in his written dialogues to that effect. Moreover, there is nothing in the dialogues to make us suppose that Plato adopted or approved the theory of Eudoxus. When Plato speaks of astronomy, either in the Republic, or in Leges, or in Epinomis, it is in a totally different spirit — not manifesting any care to save the astronomical phenomena. Both Aristotle himself (Metaphys. A. p. 1073 b.) and Simplikius, make it clear that Aristotle warmly espoused and enlarged the theory of Eudoxus. Theophrastus, successor of Aristotle, did the same. But we do not hear that either Speusippus or Xenokrates (successor of Plato) took any interest in the theory. This is one remarkable point of divergence between Plato and the Platonists on one side — Aristotle and the Aristotelians on the other — and much to the honour of the latter: for the theory of Eudoxus, though erroneous, was a great step towards improved scientific conceptions on astronomy, and a great provocative to farther observation of astronomical facts.