Pythagoras may not have discovered his own theorem, and his life is mostly legend
Every schoolchild learns the theorem named for Pythagoras, yet he left no writings, and historians doubt many of the discoveries pinned on him. The best-attested thing he taught was not geometry at all but the belief that souls are immortal and move into new bodies after death.
Ancient writers credited him with a startling list: the right-triangle theorem, a musical tuning system, the five regular solids, a round Earth, and the realisation that the morning and evening stars are both Venus. Some of these probably predate him or came from followers such as Hippasus and Philolaus. He was also said to be the first person to call himself a philosopher, a lover of wisdom.
The main biographies were written centuries later by Diogenes Laërtius, Porphyry and Iamblichus, and they grow more fantastic the further they are from his time. Earlier mentions are brief and often mocking. Later authors claimed he learned Egyptian from Pharaoh Amasis II, studied with Persian Magi, Chaldean astronomers and even Indian sages; one novelist said he got everything by interpreting dreams. Pherecydes of Syros is the teacher named most often, and the two shared a belief in reincarnation.
What can be pieced together: he was born on Samos around 570 BC, son of Mnesarchus, possibly a gem-cutter, in a trading hub famed for the Tunnel of Eupalinos. Around 530 BC, aged about forty, he left, perhaps objecting to the tyrant Polycrates, and settled at Croton in southern Italy. There he quickly became an adviser to the city's elite and founded a community whose members supposedly swore secrecy and lived simply. The wrestler Milo of Croton was said to have saved him from a collapsing roof, though that tale may confuse him with an athletics trainer of the same name.
After Croton defeated Sybaris around 510 BC, his followers clashed with democrats who set fire to their meeting houses; he was either killed or fled to Metapontum. His ideas shaped Plato's Timaeus, and centuries later Copernicus, Kepler and Newton. Ovid's portrait of him, meanwhile, fed the modern vegetarian movement.
Source: Pythagoras
