Pythagoreanism

Pythagoreanism, founded by Pythagoras of Samos in the sixth century BCE, held that number is the fundamental principle of reality — that mathematical relationships underlie and explain the structure of the cosmos. Combined with a religious doctrine of the transmigration of souls and an ethical way of life, the Pythagorean communities were as much religious brotherhoods as philosophical schools. Their mathematical discoveries and cosmological speculations profoundly shaped Plato, who incorporated Pythagorean themes throughout the Timaeus and the Republic.