Though many of René Descartes’ anatomical and physiological assumptions were vastly off target, he was the first to make a convincing case for a purely physical, nonspiritual view of life. Instead of seeing the mind and body as intimately intertwined, Descartes viewed them as interacting but separate entities. Animals, he reasoned, did not have minds, but were still capable of functioning, much like machines. Performing dissections, often on live animals, Descartes theorized about visual perception, learning, and voluntary and involuntary motor skills. Sometimes he even got it right.
This illustration appears in the first French edition of Descartes’ Treatise on Man, which was published in 1664, 14 years after his death. It was drawn by Gerard van Gutschoven, a professor of medicine at the University of Louvain in Belgium.
1 - According to Descartes, when light from external stimuli reflected onto the retina, tubules behind the eye that connect to ...