Leonardo's importance in the history of painting derives as much from his celebrated Treatise on Painting as from the touristic stampede to the ""Mona Lisa."" His prccetti for the painter transformed Renaissance art into a canon for a science of creative knowledge. The observations on human proportion, motion, perspective, light and shadow, color, and, in general, the pictorial art and its creators contributed principles that have since been taken for granted as the basis for visual representation. Now a highly competent scholar has reconstructed a lost book from the famous Treatise, and in doing it, has attained the highest level of textual analysis and historical compilation. Presented bilingually in Italian and English, hibro A gathers the material from the last part of Leonardo's life: a section on painting and a section on hydraulics, an area that intrigued da Vinci throughout his scientific works. Invaluable to art historians because of the detailed notes and new chronology for the Treatise, the book restores the order that Melzi, Leonardo's textual executor, failed to produce. Definitive modern scholarship and an obvious addition to the classical coda of pictorial art. For specialists only.