Euclid, a Greek mathematician, wrote the book "Elements, " which presented the basic principles for what is now known as Euclidian geometry. Euclid established the system of postulates and proofs still in use today in geometry. His 13-volume work remained in use in classrooms for nearly 2,000 years.
Little is known about Euclid himself. He probably lived from about 330 B.C. to 260 B.C., residing in Alexandria, Egypt, during the years between 323 B.C. and 283 B.C. when Ptolemy I was the ruler of Egypt. Euclid compiled numerous theories and proofs posted by other mathematicians into a comprehensive system. His approach to geometry was the only recognized system until non-Euclidean geometries were postulated in the 19th century.
Euclid may have studied under Plato, and most historians believe he taught at the Library of Alexandria, where he wrote his masterwork.