In 1489, Leonardo obtained a human skull. He sectioned it to investigate its internal structure, recording his findings in exquisite drawings in a notebook annotated in his habitual mirror writing (Fig. 1). But the shape of the skull (and by implication of the brain) failed to provide Leonardo with any useful information about the relationship between mind and body. The gulf between Leonardo's ambitions and his achievements brought his first wave of anatomical research to a halt. In his mural The Last Supper, finished in the 1490s, the disciples' poses and expressions convincingly capture their varied emotions, but owe nothing to his anatomical investigations.