Descartes’ Theory

A woodcut from De homine by René Descartes, published in 1662. Descartes believed that the “soul” (what we would today call the mind ) controls the movements of the muscles through its influence on the pineal body. His explanation is modeled on the mechanism that animated statues in the royal gardens. According to his theory, the eyes sent visual information to the brain, where it could be examined by the soul. When the soul decided to act, it would tilt the pineal body (labeled H in the diagram), which would divert pressurized fluid through nerves to the appropriate muscles. His explanation is modeled on the mechanism that animated statues in the Royal Gardens near Paris.  (Courtesy of Historical Pictures Service, Chicago.)