Consider this geometrical drawing, portrayed with true perspective and a mastery of light and shadow. It comes from a treatise on art and mathematics by Luca Pacioli, yet it was not drawn by Pacioli. In the preface, Pacioli explained that Leonardo da Vinci provided the geometrical figures reproduced in the last section of the book. These drawings are the only material of Leonardo’s published in print form during his own lifetime. Pacioli’s treatise is a foundational work on the “divine proportion,” or golden mean, and the mathematical principles of artistic composition, including perspective drawing. Pacioli was a teacher of Dominico di Novarra in Bologna, who was a teacher of Copernicus.