Luca Pacioli

An Italian mathematician of the early Renaissance who taught Leonardo da Vinci geometry. His vast textbook Summa de Arithmetica, Geometria, Proportioni et Proportionalita (1494) codified the symbols and methods of arithmetic, including the modern percent notation, for the next three centuries. He believed mathematics was the foundation of every careful craft (building, painting, the proportions of the human body) and devoted a whole later book, De Divina Proportione (1509), to the golden ratio.