Pythagoras was an influential Greek mathematician and philosopher, best known for the theory to which he gave his name.
Very little is known about Pythagoras's life. He is thought to have been born on the Greek island of Samos, and travelled widely in his youth, visiting Egypt and Persia. He settled in the city of Crotone in southern Italy. There he began teaching and soon had a clutch of students who lived a structured life of study and exercise, inspired by a philosophy based around mathematics. This circle came to be known as the Pythagoreans.
The early Pythagoreans were upper middle class and politically active. They formed a moral elite who strove to perfect their physical form in this life in order to gain immortality in the next. To free the soul and achieve immortality, the mortal body had to be rigorously disciplined to keep it morally pure and free of the base nature. Until this could be achieved the soul would be repeatedly reincarnated, or 'transmigrated', until released by accumulated merit.
Pythagoreans also believed in the cosmos, which at that time referred to an idea of a clockwork order and beauty in the whole universe. While probably believing in classical Greek polytheism, they maintained a superior divinity, the one, above all others. They had a number of taboos, including the avoidance of meat and beans, and lived by a series of rules governing all aspects of life. In approximately 500 BC, there appears to have been an uprising against the power of the Pythagoreans. Pythagoras fled and is thought to have been killed or died shortly afterwards.