More than 350 years ago, Rembrandt painted Anatomy Lesson of Dr. Deijman. This group portrait, featuring important members of the Amsterdam Guild of Surgeons, belongs to the series of paintings of the guild. Rembrandt’s masterpiece is one of the most famous historical images of a dissection of the brain. Unfortunately, a large part of the original painting was destroyed by a fire. Still visible, however, is how Dr Deijman, doctor of medicine and reader in anatomy, performs a dissection of the cerebral membranes in the corpse of the executed criminal Joris Fonteijn. Because there is no consensus about the nature, accuracy, and symbolic significance of the anatomic structures depicted in the painting, we compared the painting with a real anatomic dissection of the skull of a cadaver to unravel the hidden messages behind this anatomy lesson.