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**Euclid**

**Born Date:**Unknown

**Nationality:**Greek

**Influenced:**Stilpo, Thrasymachus of Corinth, Clinomachus, Eubulides, chthyas

**Teacher:**Archimedes

A Greek Socratic philosopher, Euclid of Megara founded the Megarian school of philosophy. He was a pupil of Socrates in the late 5th century BCE and was present at his death. He held the supreme good to be one, eternal and unchangeable and denied the existence of anything contrary to the good. Proclus introduces Euclid only briefly in his

*Commentary on the Elements*.

Although many results in

*Elements*originated with earlier mathematicians, one of Euclid's accomplishments was to present them in a single, logically coherent framework, making it easy to use and easy to reference, including a system of rigorous mathematical proofs which becomes the basics of mathematics after 23 centuries.
Although best known for its geometric
results, the

*Elements*also include number theory. It considers the connection between perfect numbers and Mersenne primes, the infinitude of prime numbers, Euclid's division lemma on factorization (which leads to the fundamental theorem of arithmetic), and the Euclidean algorithm for finding the highest common factor (HCF) of two numbers.
The geometrical system described in the

*Elements*was long known simply as*geometry*, and was considered to be the only geometry possible. Today, however, that system is often referred to as*Euclidean geometry*to distinguish it from other so-called*non-Euclidean geometries*which were discovered in the 19th century.