Leonardo da Vinci (1452-1519) spent over twenty-five years investigating the workings of the human body. While his paintings were widely known in his day, only a few friends and associates had any intimation of the extent of his medical research. Leonardo's Anatomical Manuscript A, created over the winter of 1510-11, is the only group of such drawings in which he approached complete coverage of the human form, and it represents his finest work in...