Pythagoras was a Greek mathematician born on the island of Samos in the 6th century BC. He traveled to Egypt to study with priests and may have learned geometric principles there that inspired his theorem. Pythagoras founded a religious cult in Croton, Italy based on principles of reincarnation and moderation. He is most famous for the Pythagorean theorem which states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.