# Euclid

**Euclid** (pronounced YOO klihd) was a Greek mathematician who lived approximately 330-270 B.C. Euclid compiled and systematically arranged the geometry and number theory of his day into the famous text "Elements." This text, used in schools for about 2000 years, earned him the name "the father of geometry." Even today, the geometries which do
not satisfy the fifth of Euclid's "common notions" (now
called axioms or postulates) are called non-Euclidean
geometries. When the Egyptian ruler Ptolemy (reports
Greek philosopher Proclus ) asked if there was a shorter
way to the study of geometry than the Elements, Euclid
told the Pharaoh that "there is no royal road to geometry."

Little is known of Euclid's life. Proclus wrote (c. 350 AD) that Euclid lived during the reign of Ptolemy and founded the first school of mathematics in Alexandria--the site of the most impressive library of ancient times (with perhaps as many as 700,000 volumes). He wrote books on other subjects such as optics and conic sections, but most of them are now lost.

**See Also:** EuclideanAlgorithm, TheElements

**Related pages** (outside of this work)