The Greek mathematician Euclid (330?-270? B.C.) is considered the “father of geometry.” He used axioms (accepted mathematical truths) to develop a deductive system of proof, which he wrote in his textbook Elements. This book proved to be a great contribution to scientific thinking and includes Euclid’s proof of the Pythagorean theorem.

Euclid’s first three postulates, with which he begins his Elements, are familiar to anyone who has taken geometry: 1) it is possible to draw a straight line between any two points; 2) it is possible to produce a finite straight line continuously in a straight line; and 3) a circle may be described with any center and radius.