Considered the most important mechanician of medieval Europe, Jordanus de Nemore is an enigmatic 13th-century figure: no biographical record survives, and all that is known comes from his own works. His Elementa Jordani super demonstrationem ponderum offered the first rigorous demonstration of the lever principle via virtual work, combining Aristotelian dynamics with Archimedean mathematical physics — influential in medieval and Renaissance statics. He also wrote the Liber philotegni on triangles, the Arithmetica in ten books, and De numeris datis on algebraic problem-solving.