He was about twenty years of age when he began to listen to Socrates. Eight years later came the death of the great teacher. Plato then left Athens and spent a number of years in travel and in study in different places. About 390 B. C., however, he returned to the city and set up a philosophical school in a garden called Academia. For forty years thereafter he was the acknowledged leader of philosophic thought and teaching in Athens.[135] His influence since his death has rested chiefly on his Dialogues, one of the most perfect literary treasures in the Greek language. The form of these beautiful compositions still reflects the question-and-answer method of Plato’s master; and the debt of the pupil is everywhere acknowledged; for in most of the Dialogues Socrates is the chief interlocutor.[136] Among the Dialogues the _Republic_ is universally recognized as the most precious; for it shows us not only his literary art at its highest, but the thought of his matured mind: it represents Plato in his strength.[137] The subject of the _Republic_ is “What is Justice?” It is thus the culmination of the ethical teaching of Socrates. Among the preliminary discussions in this book there occurs a very striking conversation between Glaucon and Socrates, in which the former gives two ideal portraits, one of a man consummately unjust, the other of a man altogether just. Here is the passage:— “But in actually deciding between the lives of the two persons in question, we shall be enabled to arrive at a correct conclusion by contrasting together the thoroughly just and the thoroughly unjust man,—and only by so doing. Well then, how are we to contrast them? In this way. Let us make no deduction either from the injustice of the unjust, or from the justice of the just, but let us suppose each to be perfect in his own line of conduct. First of all then, the unjust man must act as skilful craftsmen do. For a first-rate pilot or physician perceives the difference between what is practicable and what is impracticable in his art, and while he attempts the former, he lets the latter alone; and, moreover, should he happen to make a false step, he is able to recover himself. In the same way, if we are to form a conception of a consummately unjust man, we must suppose that he makes no mistake in the prosecution of his unjust enterprises and that he escapes detection: but if he be found out, we must look upon him as a bungler; for it is the perfection of injustice to seem just without really being so. We must, therefore, grant to the perfectly unjust man, without any deduction, the most perfect injustice: and we must concede to him, that while committing the grossest acts of injustice, he has won himself the highest reputation for justice; and that should he make a false step, he is able to recover himself, partly by a talent for speaking with