We have already mentioned (Vol. I. p. 448) that, after Socrates was put to death, Plato, like many other philosophers, fled from Athens, and betook himself to Euclides at Megara. Leaving Megara before long, he travelled first to Cyrene in Africa, where he turned his attention specially to mathematics, under the guidance of the celebrated mathematician Theodoras, whom he introduces as taking part in several of his dialogues. Plato himself soon attained to high proficiency in mathematics. To him is attributed the solution of the Delian or Delphic problem, which was proposed by the oracle, and, like the Pythagorean dogma, has reference to the cube. The problem is, to draw a line the cube of which will be equal to the sum of two given cubes. This requires a construction through two curves. The nature of the tasks then set by the oracles is very curious; on this particular occasion application had been made to the oracle in a time of pestilence, and it responded by proposing an entirely scientific problem; the change indicated in the spirit of the oracle is highly significant. From Cyrene Plato went to Italy and Egypt. In Magna Græcia he made the acquaintance of the Pythagoreans of that day, Archytas of Tarentum, the celebrated mathematician, Philolaus and others; and he also bought the writings of the older Pythagoreans at a high price. In Sicily he made friends with Dion. Returning to Athens, he opened a school of Philosophy in the Academy, a grove or promenade in which stood a gymnasium, and there he discoursed to his disciples.[4] This pleasure-ground had been laid out in honour of the hero Academus, but Plato was the true hero of the Academy who did away with the old significance of the name, and overshadowed the fame of the original hero, whose place he so completely took that the latter comes down to after ages only as connected with Plato.
Plato’s busy life in Athens was twice interrupted by a journey to Sicily, to the Court of Dionysius the younger, ruler of Syracuse and Sicily. This connection with Dionysius was the most important, if not the only external relation into which Plato entered; it had, however, no lasting result. Dion, the nearest relative of Dionysius, and other respected Syracusans, his friends, deluded themselves with vain hopes regarding Dionysius. He had been allowed by his father to grow up almost without education, but his friends had instilled into him some notion of and respect for Philosophy, and had roused in him a desire to make acquaintance with Plato. They hoped that Dionysius would profit greatly by his intimacy with Plato, and that his character, which was still unformed, and to all appearance far from unpromising, would be so influenced by Plato’s idea of the constitution of a true state, that this might, through him, come to be realized in Sicily. It was partly his friendship with Dion, and partly and more especially the high hopes he himself cherished of seeing a true form of government actually established by Dionysius, that induced Plato to take the mistaken step of journeying to Sicily. On the surface it seems an excellent idea that a young prince should have a wise man at his elbow to instruct and inspire him; and on this idea a hundred political romances have been based; the picture has, however, no reality behind it. Dionysius was much pleased with Plato, it is true, and conceived such a respect for him that he desired to be respected by him in turn; but this did not last long. Dionysius was one of those mediocre natures who may indeed in a half-hearted way aspire to glory and honour, but are capable of no depth and earnestness, however much they may affect it, and who lack all strength of character. His intentions were good, but the power failed him to carry them out; it was like our own satirical representations in the theatre, of a person who aspires to be quite a paragon, and turns out an utter fool. The position of affairs represented thereby can be nothing but this, seeing that lack of energy alone allows itself to be guided; but it is also the same lack of energy which renders impossible of execution even a plan made by itself. The rupture between Plato and Dionysius took place on personal grounds. Dionysius fell out with his relative Dion, and Plato became involved in the quarrel, because he would not give up his friendship with Dion. Dionysius was incapable of a friendship based on esteem and sympathy in pursuits; it was partly his personal inclination to Plato, and partly mere vanity, which had made him seek the philosopher’s friendship. Dionysius could not, however, induce Plato to come under any obligation to him; he desired that Plato should give himself up to him entirely, but this was a demand that Plato refused to entertain.[5]