How much of his philosophy Plato received from his master Socrates, how much he developed for himself cannot now be determined. Socrates left no writings; we know him only from the writings of others, and above all from the dialogues of Plato. There he is the chief spokesman, who leads his associates along various paths toward truth; and certainly no pupil ever built a nobler monument to his teacher than Plato did. Among modern scholars there are many views as to the extent of Plato’s debt to his master: one extreme wing, which has many adherents, would limit the Socratic elements in the Platonic doctrine to the ethical interest, the search for universals, and the dialectic method; the other wing, of which the eminent English Platonist Burnet is the chief representative, would attribute to Socrates practically everything found in the dialogues which Plato wrote before he began his teaching in the Academy. Indeed Burnet holds that Plato’s chief purpose in the earlier dialogues was to set forth the life and teaching of Socrates; he therefore claims that the “doctrine of ideas,” with all its consequences, and much besides, are purely Socratic, taken over by Plato in developed form. Few of us can accept either of these extreme views; it seems more probable that the truth lies between, that Plato learned much relating to “ideas” and their Pythagorean origins from his teacher, just as he derived from him his ethical interest and his method. But to reduce the brilliant pupil to a mere reporter of his master’s views with little philosophy of his own until he was past forty, is quite incredible, and such a procedure has no proper warrant. When speaking of Socrates in my previous lecture I avoided this question, for a discussion of it there would have been unprofitable and confusing; and even now for convenience I propose to treat that part of Plato’s philosophy which immediately concerns us as if it were wholly his own, begging you, however, to keep in mind always that undoubtedly much in germ or developed form was derived directly from Plato’s chief teacher. Furthermore I must ask you to remember that Plato had been given to poetry when a youth, and that although he renounced the practice of the art, he remained a poet in spirit to the end of his life; all his thoughts were touched with poetry, enlivened with humour, and fired with religious zeal. He was a consummate literary artist, and a man of many sides. It was natural therefore that he should nowhere set forth a crystallized system of philosophy such as a less imaginative and duller person might have done; he was apparently a man who grew through all his eighty years. The result is that in spite of the fact that we may properly speak of “the unity of Plato’s thought,” we find in his works variety, variation, and even contradiction. The requirements of our present situation, however, force us to consider our themes categorically, though that procedure is somewhat unfair to Plato.