He repaired to Athens at the age of seventeen, and soon after became a pupil of Plato. His uncommon acuteness of apprehension, and his indefatigable industry, early won the notice and applause of his master, who called him the "mind" of the school, and said, when he was absent, "Intellect is not here." On the death of Plato, Aristotle left Athens, and in 343 he repaired to Macedonia, on the invitation of Philip, and became the instructor of the young prince Alexander. In after years Alexander aided him in his scientific pursuits by sending to him many objects of natural history, and giving him large sums of money, estimated in all at two millions of dollars. In the year 335 Aristotle returned to Athens, and opened his school in the Lyce'um. He walked with his scholars up and down the shady avenues, conversing on philosophy, and hence his school was called the peripatetic. Aristotle nowhere exhibits the merits of Plato in the service of metaphysics, yet he was the most learned and most productive of the writers of Greece. He had neither the poetical imagination nor the genius of his teacher, but he mastered the whole philosophical and historical science of his age, and, more than Plato, his intellect has influenced the course of modern civilization. He was eminently a practical philosopher--a cold inquirer, whose mind did not reach the high and lofty teaching of Plato, concerning Deity and the destiny of mankind. We find the following just estimate of him in BROWNE'S Greek Classical Literature: "One cannot set too high a value on the practical nature of Aristotle's mind. He never forgot the bearing of all philosophy upon the happiness of man, and he never lost sight of man's wants and requirements. He saw the inadequacy of all knowledge, unless he could trace in it a visible practical tendency. But, beyond this one single point, he falls grievously short of his great master, Plato. All his ideas of man's good are limited to the consideration of this life alone. It is impossible to trace in his writings any belief in a future state or immortality."