and dedicated to him a poem, of which we shall hear more in the sequel. About B.C. 343, when he was over forty years old, he was called to Macedonia, as tutor to Alexander, the thirteen-year-old son of King Philip, and grandson of his own father's old patron, Amyntas. This office he filled for about three years with distinguished success, and it may be safely said that never had so great a tutor so great a pupil. During the latter part of the time, at least, Aristotle and Alexander seem to have lived at Stagira. This town had been captured and destroyed by Philip, and its inhabitants scattered. With the permission of the conqueror, Aristotle reassembled the inhabitants, rebuilt the town, drew up its laws, and laid out near it, at Mieza, in imitation of the Academy, a gymnasium and park, which he called the _Nymphæum_. Hither he appears to have retired with his royal pupil and several other youths who were receiving education along with him, among them Theophrastus and the ill-fated Callisthenes. It was probably here that Aristotle adopted the habit of walking while imparting instruction, a habit which afterwards gave the name to his school. When Alexander, at sixteen, entered his father's army, Aristotle still continued to teach in the Nymphæum, which existed even in Plutarch's time, more than four hundred years afterwards. But this lasted only for about five years; for in 335, when Alexander, who in the previous year had succeeded his murdered father, was preparing to invade Persia, Aristotle moved to Athens. Finding that his old friend, Xenocrates, was director of the school in the Academy, he established himself, as a public teacher or professor, in the Lyceum, the Periclean gymnasium, used chiefly, it should seem, by the lower classes and by foreign residents, of whom he himself was one. As an alien, as the friend of the victorious Macedonians, who three years before had broken the power of Greece at Chæronea, and taken away her autonomy forever, as a rival of the Platonists, and as a wealthy, well-dressed gentleman, he had many enemies and detractors; but his conduct seems to have been so unobjectionable that no formal charge could be brought against him. His very numerous pupils were mostly foreigners, a fact not without its influence on the subsequent course of thought. He divided his days between writing and teaching, taking his physical exercise while engaged in the latter occupation. In the mornings he gave lectures to a narrow circle, in a strictly formal and scientific way, upon the higher branches of science; while in the afternoons he conducted conversations upon more popular themes with a less select audience. The former were called his esoteric, the latter his exoteric, discourses.