by two journeys to Sicily, he continued to teach for about forty years, dying in 347 B.C. at the age of eighty. To this school came pupils from almost every part of the Greek world. The chief subjects studied were the various branches of mathematics—including of course astronomy and harmonics,—and dialectics, by which is meant “the art of question and answer, the art of giving a rational account of things and of receiving such an account from others.” The distinctive methods employed were those of analysis and division which Plato seems to have developed so far that the invention of the former was actually, but erroneously, attributed to him. The purpose of analysis was to secure an explanation or proof of a proposition; that of division was to arrive at a proper classification or division of the object under consideration. Plato’s instruction was evidently given in considerable part by lectures, of which his hearers took notes; there was also scientific research on the part of the pupils who worked out the problems or difficulties set them by their master. Nor were these researches wholly mathematical and astronomical, for there is good reason to believe that studies in natural history were also pursued. Indeed, Aristotle, for twenty years a member of the Academy, must have had opportunities here to carry on those researches which interested him most in the early part of his life. But whatever the studies, the purpose was to lead the pupils to the discovery and contemplation of Reality, of Being, of the fundamental and permanent as against the individual and transitory phenomenon. Of Plato’s lectures we know virtually nothing; his Dialogues represent those parts of his doctrine which he wished to give to the outside world; it is probable that they in no sense adequately reproduce his teachings to his disciples.