Joseph Liouville (1809–1882) was a French mathematician who worked across an astonishing range of subjects and had a knack for asking the questions nobody else thought to ask. He also founded a famous journal and became one of the great talent-spotters of his century.
Liouville's theorem in complex analysis is a real showstopper: it says that a function that is
Years earlier, a young hothead named Évariste Galois had scribbled revolutionary ideas about the solvability of equations and then died in a duel at twenty, his work dismissed and ignored. Liouville, sifting through the neglected manuscripts, realised they were the work of a genius — and he published and championed them until the whole mathematical world understood. Without Liouville's patient reading, one of the deepest theories in algebra might have been lost for good. A great mathematician, and an even greater rescuer of one.