So far we have followed the evolution of Plato’s philosophy as it may have been effected under the impulse of purely theoretical motives. We have now to consider what form was imposed on it by the more imperious exigencies of practical experience. Here, again, we find Plato taking up and continuing the work of Socrates, but on a vastly greater scale. There was, indeed, a kind of pre-established harmony between the expression of thought on the one hand and the increasing need for its application to life on the other. For the spread of public corruption had gone on _pari passu_ with the development of philosophy. The teaching of Socrates was addressed to individuals, and dealt chiefly with private morality. On other points he was content to accept the law of the land and the established political constitution as sufficiently safe guides. He was not accustomed to see them defied or perverted into instruments of selfish aggrandisement; nor, apparently, had the possibility of such a contingency occurred to him. Still less did he imagine that all social institutions then existing were radically wrong. Hence the personal virtues held a more important place in his system than the social virtues. His attacks were directed against slothfulness and self-indulgence, against the ignorant temerity which hurried some young men into politics before their education was finished, and the timidity or fastidiousness which prevented others from discharging the highest duties of citizenship. Nor, in accepting the popular religion of his time, had he any suspicion that its sanctions might be invoked on behalf of successful violence and fraud. We have already shown how differently Plato felt towards his age, and how much deeper as well as more shameless was the demoralisation with which he set himself to contend. It must also be remembered how judicial proceedings had come to overshadow every other public interest; and how the highest culture of the time had, at least in his eyes, become identified with the systematic perversion of truth and right. These considerations will explain why Greek philosophy, while moving on a higher plane, passed through the same orbit which had been previously described by Greek poetry. Precisely as the lessons of moderation in Homer had been followed by the lessons of justice in Aeschylus, precisely as the religion which was a selfish traffic between gods and men, and had little to tell of a life beyond the grave, was replaced by the nobler faith in a divine guardianship of morality and a retributive judgment after death—so also did the Socratic ethics and the Socratic theology lead to a system which made justice the essence of morality and religion its everlasting consecration.