There is not the slightest doubt among historians that the great Pythagoras was a son of Samos. He was born in the 50th Olympiad, that is, 580-574 BC. His father was Mnesarchus, who was from Etruria, but who settled , lived and died on Samos. His mother, Parthenia, was a descendant of Angaeus, the first King of Samos.
Pythagoras had two brothers, Eunomus and Tyrrhenus, and a sister, Themistocleia. There is a whole host of myths about the birth of Pythagoras. Porphyrius tells us that a Samiot poet was responsible for the myth that Pythagoras was the son of Apollo and the Pythian priestess of Delphi. The poet Iamblichus says that Mnesarchus, the father of Pythagoras, asked the Pythian priestess at the Delphic oracle if the journey which he was about to undertake would be pleasant and profitable. The oracle replied that his affairs would prosper; it also told him that his wife, Parthenia, who was pregnant at the time, would give birth to a son who "would never be exceeded in beauty and wisdom".

Mnesarchus, realizing that the child to be born was sent by the gods, renamed with his wife Pythaes and called his new-born son Pythagoras, because the Pythian priestess had made a prophecy about him. As Pythagoras grew up, he acquired wisdom. Pythagoras was the pupil of Pherecydes, who was then living on Samos, and took lessons from Hermadamas. At the age of 18, he visited Thales at Miletos and asked him to teach him more than the sages of Samos had. He was 60 years old when he returned to Samos. In the meantime, he had visited Athens, where he learned about the laws of Solon, and Sparta, where he learned about those of Lycurgus. He won two victories in the Olympic Games and offered sacrifice to Apollo on Delos. He also visited Crete.

On Samos he set up a school which was called the "Pythagorean Semicircle". He was prepared to teach anyone who came there to hear him. The philosopher Anaximander of Miletos did not approve of Pythagoras's philosophical and mathematical theories and accused him of being a trouble-maker and infidel. Pythagoras rejected these accusations, but was forced by his enemies to take refuge in a cave of Month Kerkis, and then to leave Samos.

He married a woman called Theano and had many children. At one stage he settled in the city of Croton in Lower Italy, where he set up a school which rapidly acquired a tremendous reputation. Pupils came from every quarter of the world to study under him and to make the personal acquaintance of this wise teacher. His method of teaching was known as "hairesis". In order to enroll his school, candidates had to undergo certain tests. Pythagoras himself would investigate their charter, habits, feelings, words, actions and their way of life in general. Only if they successfully passed all these test were they accepted as disciples. Then they would have to give all their property to the school, as everything was held in common. For three years, the disciples had no vote in proceedings and no medical treatment. After that they were required to observe silence for five years. Thus they were trained to tame their own selves, first to listen and then acquire wisdom.

For all this period, the disciple was regarded as a "novice" and was not allowed to present himself before Pythagoras. If after all this the pupil was considered unsuitable, he was expelled and his property returned. The Pythagoreans lived a common life together in one building and were divided into groups. Some of these studied geometry and some astronomy.

It was Pythagoras who discovered the planet Venus, which he called Hesperus and Phosphorus. The guest of the Pythagoreans was for the unity of the laws governing nature. They assigned great importance to the number four. To begin with, there was the single unit. From this they said, came the indefinite duality. From the single unit and the indefinite duality came the numbers. From numbers came points and from these lines, for lines came plane figures, and from these solid bodies, including the four elements; Earth, Air, Fire and Water.

The Pythagoreans ascribed a certain musical energy to everything to be found in the world (cosmos = order). Pythagoras was the first to call the heavens "cosmos", because they are adorned with life and were created by a kind of harmony, which was later imitated by the lyre. It was this harmony which gave sound to the revolving movement of the heavenly bodies.
As a first course of study Pythagoras recommended geometry in which he had made great advances, solving the famous problem of the hypotenuse of a right-angled triangle. It is dais that when he found the answer he scarified 100 oxen to the god.

Pythagoras developed the theory that animals are generated one from another by means of sperm, since sperm according to him is a drop of brain matter which contains hot steam. His doctrine of the transmigration of souls had its beginning in an attempt to find the perfection of human society; it is really the doctrine of the immortality of the soul mixed up with various speculations. Pythagoras's contemporaries did not accept these theories, and he was much ridiculed and frequently suffered persecution.

The philosopher was also a physician. His advice was to lead a simple life with a plain diet, eating uncooked foods and drinking cold water. This was, in his view, the way to give health and vigour to the body. The above is a brief summary of the teachings of this great philosopher, who was also the first to teach the Greeks to use weights and measures.

Historians differ as to the way in which Pythagoras met his death. Some say that he died at Croton in Italy at the age of between 90 and 100, and some that he perished when an angry mobset fire to his school.