Most of the details of Pythagoras’s early life are uncertain, dating to writers of much later date. Some things, however, seem to have a certain degree of reliability. There is no genuine description of his appearance although he is though to have had an unusual birthmark on his thigh. He probably had siblings, but the sources differ whether he had two or three brothers. It seems certain that his education was extensive. Besides the “mystical” Chaldaeans, he also was educated in Greek philosophy. Sources name Pherekydes, Thales, and Anaximander as his tutors. These last two lived at Miletus would have furthered Pythagoras’ education in mathematics (especially geometry) and astronomy.
Pythagoras returned home to Samos where he became friends with Polycrates, who had seized power at tyrant on the island. Carrying letters of introduction from Polycrates, Pythagoras visited Egypt in c535 BC, where he was allowed to visit a number of temples and be familiarized with many of the Egyptian mysteries. These seem to have brought him even greater enlightenment into the mysteries of mathematics.
In 525 BC, Pythagoras was still in Egypt when he was caught up in the Persian invasion under Cambysis II. Taken prisoner by the Persians, he was taken as a captive to Babylon. While there he made the best of his situation by learning all that he could about the religion, mysticism, arts and sciences of the Babylonians. It was here that he discovered much about the relationships of mathematics and music.
Having regained his freedom, Pythagoras returned to Samos in c520 BC. There is some conflict in the sources as to whether the island was still under the rule of Polycrates at this time or under Persian control. Soon after this Pythagoras visited Crete, where spent time studying law. Upon returning to Samos, he founded his first school, known as the Semicircle, in which he began to reveal some of the knowledge that he gained over the years.
The date and the reason for Pythagoras’s final departure from Samos are much debated. According to Iamblichus, his teachings were not well received by the Samians and he found himself constantly being imposed upon for civic duties. Whatever the causes, Pythagoras abandoned his school at Samos and relocated himself at Croton (modern Crotone) in Magna Graecia. There are a wide range of dates as to when Pythagoras moved to Italy. Sources put it as early as c530 BC to as late as c518 BC.
Pythagoras found Croton a most welcoming place and he was given unrestricted license in establishing his school there. Thanks to his influence, Croton was to enter a period of great economical prosperity and political dominance, and military strength. The Pythagorean School will spread throughout much of the Greek world and have a long-lasting effect on western thought for centuries thereafter. The school centered on an inner circle of male and female initiates known as mathematikoi. This group lived permanently within the Society under the direct control of Pythagoras, renouncing all personal possessions and subsisting on a strict vegetarian diet. The majority of the Society consisted of an outer circle known as the akousmatics. Members of the outer group lived in their own homes and had access to the Society only at in the daytime. Unlike the mathematikoi, the akousmatics had no restrictions on their diet or behavior and could own personal possessions.
Pythagoreanism was based particular principles:
1. True reality is based on mathematics.