Euclid (Greek: Εὐκλείδης — Eukleídēs), fl. 300 BC, also known as Euclid of Alexandria, was a Greek mathematician and's often referred to as the "Father of Geometry." He was active in Hellenistic Alexandria during the reign of Ptolemy I (323–283 BC). His Elements's the most successful textbook and one of the most influential works in the history of mathematics, serving as the main textbook for teaching mathematics (especially ge… (More on Euclid)