The biography of Pythagoras of Samos is embroidered with legend, and what the Neo-Pythagoreans tell us is interwoven with Platonic and Aristotelian ideas. His very name — he whose birth was foretold by the Pythian god, Apollo, or he who utters oracles as does Apollo — gives a hint of the mystery enveloping his personality. This at least is certain, that he was born about 580 B.C. as the son of a well-to-do merchant, Mnesarchus. Tradition has it that as a young man he spent a fairly long period in Egypt in order to familiarize himself with the cults of Isis and Osiris. There, too, so runs the tale, he acquired his mathematical knowledge from which he later developed his system of numbers. Upon his return to Greece, he visited first of all such religious centers as Delphi, Delos and Crete with a view to initiation in their mystic rites. In his native island, Samos, he then began to teach, but dissastisfied with the rule of Polycrates the tyrant, he soon resolved to seek out the Greek colonies of Southern Italy.