Luca Pacioli (1445-1514 or 1517) was an Italian mathematician and Franciscan friar who lived during the Renaissance. While he was the chairman of mathematics in Milan, he collaborated with and taught mathematics to Leonardo da Vinci. He published his second important book De divina proportione, in 1509. This book discussed topics including mathematical proportion, geometry, and architecture. Along with beautiful three-dimensional renderings by da Vinci, Pacioli included diagrams detailing the geometric construction of the Roman alphabet.