**Pythagoras**lived in **5th century BC. C.**was one of the main Greek philosophers and mathematicians of the**pre-Socratic era**. Born in**island of** **Samos**moved to Magna Graecia and gathered around him a group of disciples, together with whom he developed a new **philosophical system based on numbers**. Pythagoras, however, was interested in all fields of human knowledge. In his time scholars were dealing with various sciences and Pythagoras, in addition to being a philosopher and a mathematician, was interested in **astronomy **and of **anatomy**. Although he is best known for his **theorem** which bears his name, he was most likely not the first scholar to discover it.

## Who was Pythagoras, the philosopher who gave birth to the Pythagorean school

Of the life of a Greek philosopher and mathematician **very little is known**, because all ancient sources present it in rather enigmatic terms. According to most historians, Pythagoras was born on the island of **Samos**, in the Aegean Sea, in the first half of the 6th century BC. probably **between 580 BC and 570 BC**

He got married to a certain woman **Theano** and had five children with her. At an unspecified time in her life he moved to **Crotone**a Greek city in southern Italy, perhaps because it had come into conflict with **Polycrates**, the “tyrant” (in the sense of monarch) of Samos. In Croton, Pythagoras gathered a group of followers and towards the **530 BC** gave birth to a philosophical current, the **Pythagorean school**. He died around 495 BC **Metaponto**a Greek city in Basilicata, where he moved following the outbreak of a revolt in Crotone.

**Pythagoras’ ideas: philosophical thought**

Pythagoras never wrote down his theories (or, if he did, his works are lost), but explained them orally to his disciples. His ideas are rather obscure, but we know that he developed a philosophical system based on numbers: he believed that **all existing realities were composed of numbers**, understood not as abstract concepts, but as real quantities. More precisely, the number one represented the point, two the line, three the surface, four the solid. The first four numbers, arranged in a pyramid, constituted the * tetraktys,* which for the Pythagoreans had a religious value.

The universe, being based on precise numerical proportions, was an ordered system for Pythagoras. You owe him the concept * kosmos,* which in Greek means “orderly” and is the same word from which Italian terms such as cosmetic, cosmesi, etc. derive. Furthermore, the philosopher was one of the first to put forward the idea that the Earth was not at the center of the universe: he believed that at the center there was a fire, around which our planet and other celestial bodies, including the Sun, revolve. .

Pythagoras was also a supporter of **reincarnation **and he thought that the soul was reincarnated after death in other bodies. However, while supporting theories of this kind, he made an important contribution to**human anatomy **and he was the first to hypothesize that the “engine” of sensations was not the heart, as was generally believed at the time, but the brain.

Some ancient sources report that Pythagoras was the inventor of the word “philosophy”, understood as love of wisdom, but many modern scholars believe that the word already existed before him.

**What the philosopher discovered: the Pythagorean theorem**

The interest in numbers pushed Pythagoras and his followers to become interested in mathematics, to the progress of which they made an important contribution. Although it is not easy to define the discoveries of the Pythagoreans, it is probable that they discovered the **irrational numbers**the ratio between even and odd numbers, the characteristics of **regular solids **and various properties of geometric figures.

Pythagoras’ best-known “discovery” is the theorem that bears his name, the formulation of which can be summarized in these terms: “In every right-angled triangle, the square constructed on the hypotenuse is equivalent to the union of the squares constructed on the cathetes” . It follows that, knowing the measurement of two sides, the third can be calculated.

The theorem **it was not “invented” by Pythagoras**, but it was already known to the Babylonians, Egyptians, and the Indian and Chinese civilizations. The Greek philosopher, however, was most likely the first to give one **indisputable proof** or at least the first to do so in the current West.

**The rules of the Pythagoreans and the fear of beans**

The school of Pythagoras adhered to one **set of rules**, handed down to us from some ancient sources that are not easily understandable today. Among them were the prohibitions on touching white roosters, walking on main roads and letting swallows into the house. The best known rule was the **ban on eating broad beans**, on which Pythagoras was very rigorous. An anecdote tells that, chased by his enemies, he preferred to be killed rather than cross a field of beans to escape. Modern scholars have proposed various interpretations to explain the philosopher’s hostility to broad beans. It has been suggested that he believed them **endowed with a soul **or that he was worried about the **favism**a hereditary disease that prevents you from eating broad beans and other foods.