Euclid

Euclid (fl. c. 300 BCE) was a Greek mathematician active in Alexandria during the reign of Ptolemy I Soter. He is best known for the Elements, a thirteen-book treatise that systematized geometry, number theory, and proportion through axioms, definitions, and deductive proofs, and which served as a foundational mathematics text for over two millennia. Beyond the Elements, he wrote works on astronomy and applied geometry, including the Phaenomena, a treatise on spherical astronomy, and the Data, which examines what can be inferred about geometric figures from given conditions. Almost nothing is reliably known about his life; the traditional date places his floruit around 300 BCE, with his work centered at Alexandria.