You memorized his triangle equation in school, but what if the so-called father of mathematics never proved a single theorem? Meet the real Pythagoras: a charismatic mystic with a golden thigh who believed he was the reincarnation of a Trojan war hero, a fisherman, and a beautiful courtesan.

This deep dive peels back centuries of myth, much of it invented by later Neoplatonists trying to build a pagan icon, to reveal a man who ran a totalizing monastic cult in Croton. We trace how his strange teachings on reincarnation, ritual purity, and the harmony of the spheres shaped Western philosophy and science, even though the famous theorem was known to the Babylonians a thousand years earlier.

• Why almost nothing about Pythagoras is first-hand, and how the Neoplatonists Porphyry and Iamblichus built his legend
• The five-year vow of silence initiates endured and the split between the mathematikoi and the akusmatikoi
• His literal belief in metempsychosis, including begging a man to stop beating a dog he thought held a dead friend’s soul
• The strange daily rules, from right-sandal-first to the deadly prohibition on eating fava beans
• How the cult ended in a violent revolt led by the rejected initiate Cylon, and Pythagoras’s death at the edge of a bean field