Pythagoras was a teacher of many things. He developed the theory that the soul passes into another body after death. He developed a whole way of life which would lead to salvation. He believed souls could be contained in animals. He said that have heard the voice of a dead friend in the howl of a dog being beaten.
He also believed that numbers could reveal the secrets of the universe. He had such great respect for theories about numbers that he swore his oaths by it. The mathematical knowledge carried out by Pythagoras and his followers made him important in the history of western thought. He presented the idea that life is controlled by opposite forces between limited and unlimited.