Leonardo da Vinci, the Renaissance artist, contributed to the early history of neuroscience. Two sketches1 particularly show that his understanding of the brain and sensorial perceptions developed over time. Figure 1 (c. 1490) demonstrates the importance of theoretical knowledge. The ventricles, the only cerebral structures depicted, appear as 3 connected spheres attached to the eye. This reflected medieval medical theory that associated the ventricles’ locations to specific functions, such as memory.2 In figure 2 (c. 1508), direct observation plays a greater role. Empirical investigations of the brain inspired these later and more anatomically accurate drawings—sometimes referred to as “Renaissance brain imaging.” In the accompanying notations, Leonardo concluded that mental functions were not housed in ventricular cavities.