Pythagoras' wide-ranging interests in mathematics, music, and astronomy mark him as a seminal figure in early western civilization's intellectual development. In the realm of mathematics, he developed the Pythagorean theorem and discovered irrational numbers. Pythagoras also founded a philosophical and religious school steeped in mysticism and secrecy which left its mark on poets, artists, scientists, and philosophers down to the 20th century.

Pythagoras was born about 580 B.C., probably in Samos, Greece, where he grew up. His father, Mnesarchus, may have been an engraver of seals or a merchant. Living in a prosperous seaport that was the center of learning and art during the Golden Age of Greece stimulated Pythagoras' thirst for knowledge. However, conflicting reports and the lack of written records leave much of his early life a matter of conjecture. Some reports indicate that he had at least two elder brothers, was a champion athlete, and...