Hailed by Dante as "the master of those who know," the Greek philosopher Aristotle (384???322 B.C.) surveyed every field of learning known to the ancient world and pioneered the sciences of psychology and logic. A disciple of Plato and the tutor to Alexander the Great, Aristotle was a prolific writer, although many of his works have been lost. His treatises, used by the students of his famous Athenian school, the Lyceum, exerted a profound and lasting influence on Western thought. Aristotle's Nicomachean Ethics is one of the world's great books. Identifying happiness as the goal of life, he rejects pleasure, fame, and wealth as means to it. The summit of human achievement is attainable only through the contemplation of philosophic truth, because this practice exercises the virtue peculiar to the human being, the rational principle.