Pythagoras, a celebrated Greek philosopher and founder of a school named after him Pythagoreans, born at Samos, and who seems to have flourished between 540 and 500 B.C.; after travels in many lands settled at Crotona in Magna Græcia, where he founded a fraternity, the members of which bound themselves in closest ties of friendship to purity of life and to active co-operation in disseminating and encouraging a kindred spirit in the community around them, the final aim of it being the establishment of a model social organisation. He left no writings behind him, and we know of his philosophy chiefly from the philosophy of his disciples.