The year 1996 marked the quattrocentenary of Descartes' birth. This paper reviews his pineal neuropsychology. It demonstrates that Descartes understood the true anatomical position of the pineal. His intraventricular pineal (or glande H) was a theoretical construct which allowed him to describe the operations of his man-like “earthen machine.” In theTreatise of Manhe shows how all the behaviors of such machines could then be accounted for without the presence of self-consciousness. Infrahuman animals are “conscious automata.” InPassions of the Soulhe adds, but only for humans, self-consciousness to the machine. In a modern formulation, only humans not only know but know that they know.