Rafello Bombelli was the last of a long line of Italian algebraists who contributed to the theory of equations during the Renaissance. He was the first to develop a consistent theory of imaginary numbers which included the rules for the four operations on complex numbers. Gottfried Wilheim von Leibniz complimented Bombelli years later referring to him as an "outstanding master of the analytical art."

Bombelli was born in 1526 in Bologna, Italy. His father, Antonio Bombelli, was a wool merchant. Bombelli choose not his father's profession but instead became an engineer. He never attended any university but instead was trained by Pier Francesco Clementi of Corinaldo, who as an engineer-architect was responsible for draining swamps. For the major part of his working life, Bombelli was employed as an engineer under the patronage of Monsignor Alessandro Rufini, who later became the Bishop of Melfi. Bombelli's engineering career included two major...