Pythagoras was a Greek philosopher and mathematician. Born in what is modern-day Greece, Pythagoras migrated to southern Italy about 532 B.C., apparently in an effort to escape the merchant and territorial ruler Samos's tyrannical ways. After he arrived in southern Italy, Pythagoras proceeded to establish his ethical and political academy at Croton (now Crotone, Italy). At this academy, he founded the Pythagorean brotherhood, which, although religious in nature, formulated principles that influenced the thought of Greek philosophers Plato and Aristotle. In addition, it contributed to the development of mathematics and Western rational philosophy. Pythagoreans followed a very structured way of life. They believed that the human soul resided in a new human or animal body after a person died.

It is difficult to distinguish Pythagoras's teachings from those of his disciples. None of his writings have survived, and Pythagoreans invariably supported their doctrines by indiscriminately citing their master's authority. Pythagoras, however, is generally credited with the theory of the functional significance of numbers in the objective world and in music. Other discoveries often attributed to him (e.g., the incommensurability of the side and diagonal of a square, and the Pythagorean theorem for right triangles) were probably developed only later by the Pythagorean school. More probably the bulk of the intellectual tradition originating with Pythagoras himself belongs to mystical wisdom rather than to scientific scholarship. . .