Only a few people accepted Descartes’ pineal neurophysiology when he was still alive, and it was almost universally rejected after his death. Willis wrote about the pineal gland that “we can scarce believe this to be the seat of the Soul, or its chief Faculties to arise from it; because Animals, which seem to be almost quite destitute of Imagination, Memory, and other superior Powers of the Soul, have this Glandula or Kernel large and fair enough” (Willis 1664, ch. 14, as translated in Willis 1681). Steensen (1669) pointed out that Descartes’ basic anatomical assumptions were wrong because the pineal gland is not suspended in the middle of the ventricles and is not surrounded by arteries but veins. He argued that we know next to nothing about the brain. Camper (1784) seems to have been the very last one to uphold the Cartesian thesis that the pineal gland is the seat of the soul, although one may wonder whether he was completely serious. In philosophy, a position called “Cartesian interactionism” immediately provoked “either ridicule or disgust” (Spinoza 1677, part 4, preface), usually because it was seen as raising more problems than it solved, and it continues to do so to this day, but as we have already indicated, it is doubtful whether Descartes was a Cartesian interactionist himself.