Pythagoras was an ancient Ionian Greek philosopher. His political and religious teachings influenced the philosophies of Plato and Aristotle. Knowledge of his life is clouded by legend, but he appears to have been the son of a gem-engraver on the island of Samos. Modern scholars disagree regarding Pythagoras' education and influences, but they do agree that, around 530 BC, he travelled to Croton in southern Italy, where he founded a school in which initiates lived a communal, ascetic lifestyle. 

The teaching most identified with Pythagoras is the "transmigration of souls", which says that every soul is immortal and, upon death, enters into a new body. He may have also devised the doctrine of musica universalis, which holds that the planets move according to mathematical equations and thus resonate to produce an inaudible symphony of music. 

Pythagoras was credited with many mathematical and scientific discoveries, including the Theory of Proportions, the sphericity of the Earth, and the identity of the morning and evening stars as the planet Venus. It was said that he was the first man to call himself a philosopher (lover of wisdom). Pythagoras was regarded as a influential thinker throughout the Middle Ages and his respected authority had a major impact on scientists such as Nicolaus Copernicus, Johannes Kepler, and Isaac Newton.