Bonaventura Cavalieri

Bonaventura Francesco Cavalieri was born in 1598 and took vows as a Jesuate, a now-extinct religious order that blended devotion with scholarship. His mathematics broke ground on optics and motion, but the lever was his work on indivisibles: the idea that a figure could be treated as an infinite stack of lines or planes, each with no thickness. The principle that bears his name - comparing solids by comparing their cross-sections - gave geometers a powerful shortcut and foreshadowed the integral calculus Newton and Leibniz would formalize decades later. He also brought logarithms across the Alps into Italian mathematics. Cavalieri died on 30 November 1647, his indivisibles still controversial but quietly reshaping the field.