Born:c. 570 BC, Samos, Greece
Died:c. c. 495 BC, Metapontum, Italy
Famous for:Pythagoras' theorem

Biography of Pythagoras

Pythagoras was an ancient Greek philosopher, mathematician and founder of a religious movement. He is most famous for Pythagoras' Theorem.

Pythagoras' Life

Pythagoras lived from about 570-495 BC. He was born on the Greek island of Samos, but spent most of his life in Greek colonies in Sicily and southern Italy. He travelled widely, visiting Egypt and Babylon.

The Pythagorean School and Movement

Pythagoras set up a school, which was part a centre of learning, part a religious movement.

Pythagoras and his followers lived together in their own community, devoting their time to learning and living by a strict ethical code. His followers were vegetarians, didn't eat beans, wore their hair long, and weren't allowed personal possessions. Mathematics was not just a technical subject for the Pythagoreans, it had mystical importance. Numbers had personality and meaning. The Pythagoreans believed that they were behind everything in the Universe. A keen musician, Pythagoras discovered important mathematical patterns in music. For instance, when plucking a string, there are ratios of string lengths that give different harmonies. He also was interested in Astronomy, and would noticed the mathematical regularities in the movement of the stars in the heavens.

Pythagoras' Theorem

Pythagoras' theorem is a theorem in geometry concerning the three sides of a right triangle. Pythagoras' theorem (or the Pythagorean theorem) states that:
The square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two sides.
It is easier to remember Pythagoras' theorem as a formula:

In the formula, c is the length of the hypotenuse (the longest side, opposite the right angle) and a and b are the lengths of the other two, shorter sides. The image below shows what we mean:

Pythagoras' theorem was not invented by Pythagoras. The Babylonians and Indians were aware of it many centuries before he lived. But Pythagoras was the first to prove that it is true.

Lesson Slides

The slider below shows Pythagoras' Theorem. Open the slider in a new tab

What's in a Name?

Pythagoras' name was explained by the philosopher Aristippus: "He spoke (agor-) the truth no less than did the Pythian (Pyth-)". The Pythian refers to the Oracle at Delphi, a priestess who many came to see for her prophesies. According to another philosopher, Iamblichus, the Pythian prophesied to Pythagoras' mother, when she was pregnant with him, that she would give birth to a man supremely beautiful, wise, and beneficial to mankind.

Pythagorean Beliefs

Pythagoras' followers believed in the transmigration of the soul - that a person's soul would come back in another person, animal or vegetable after death. By leading a pure life, the soul could ascend until its ultimate purification. A story is told of how Pythagoras' stopped a man from beating a dog, because he thought he heard the voice of a recently deceased friend in the dog's cries.