The Greek mathematician Euclid worked in Alexandria, Egypt, 2,300 years ago. Few details of his life remain, but he is famous for writing Elements, a series of 13 books.

These contained geometric principles and theorems that were to form the basis of mathematics for more than 2,000 years. In fact, these books were so clearly written that updated versions were still in use in schools in the early 1900s. Although some of Euclid's theorems still hold good today, mathematician and physicist Albert Einstein (1879–1955) later proved that Euclid's geometry was not valid throughout space and time. Euclid also wrote on music and other subjects.

The ideas of the Greek mathematician and philosopher Pythagoras contributed to the development of modern mathematics and Western philosophy. His aim was to explain all natural phenomena in terms of mathematics. Pythagoras is best known for his formula for the proportions of the sides of a right-angled triangle. However, many other concepts and notations (such as arithmetic and geometric sequences and square numbers) fundamental to modern mathematics are based on Pythagoras's ideas. He and his followers worked out the mathematics of the harmonics that form the basis of Western music today.

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