Did you know the most famous book in mathematics has no numbers at all? Euclid (Greek: Εὐκλείδης, fl. 300 BC), sometimes called Euclid of Alexandria, was a Greek mathematician, often referred to as the "founder of geometry" or the "father of geometry". He was active in Alexandria, Egypt during the reign of Ptolemy I (323–283 BC). His Elements is one of the most influential works in the history of mathematics, serving as the main textbook for teaching mathematics (especially geometry) from the time of its publication until the 20th century. In the Elements, Euclid deduced the theorems of what is now called Euclidean geometry from a small set of axioms.