Pythagoras (570?–495? B.C.), the most famous of the pre-Socratic Greek philosophers. He emigrated from the island of Samos (off Asia Minor) to Croton (southern Italy) in 530. There he founded societies based on a strict way of life. They had great political impact in southern Italy and aroused opposition that resulted in the burning of their meeting houses and, ultimately, in the societies’ disappearance in the fourth century B.C. Pythagoras’s fame grew exponentially with the pasage of time. Plato’s immediate successors in the Academy saw true philosophy as an unfolding of the original insight of Pythagoras. By the time of Iamblichus (late third century . .), Pythagoreanism and Platonism had become virtually identified. Spurious writings ascribed both to Pythagoras and to other Pythagoreans arose beginning in the third century B.C. Eventually any thinker who saw the natural world as ordered according to pleasing mathematical relations (e.g., Kepler) came to be called a Pythagorean. Modern scholarship has shown that Pythagoras was not a scientist, mathematician, or systematic philosopher. He apparently wrote nothing. The early evidence shows that he was famous for introducing the doctrine of metempsychosis, according to which the soul is immortal and is reborn in both human and animal incarnations. Rules were established to purify the soul (including the prohibition against eating beans and the emphasis on training of the memory). General reflections on the natural world such as ‘number is the wisest thing’ and ‘the most beautiful, harmony’ were preserved orally. A belief in the mystical power of number is also visible in the veneration for the tetractys (tetrad: the numbers 1–4, which add up to the sacred number 10). The doctrine of the harmony of the spheres – that the heavens move in accord with number and produce music – may go back to Pythagoras. It is often assumed that there must be more to Pythagoras’s thought than this, given his fame in the later tradition. However, Plato refers to him only as the founder of a way of life (Republic 600a9). In his account of pre-Socratic philosophy, Aristotle refers not to Pythagoras himself, but to the ‘so-called Pythagoreans’ whom he dates in the fifth century. See also ARCHYTAS, PHILOLAU. C.A.H.