directed into the appropriate nerves. It was Descartes' articulation of this mechanism for automatic, differentiated reaction that led to his generally being credited with the founding of reflex theory. Although extended discussion of the metaphysical split between mind and body did not appear until Descartes' Meditationes, his De homine outlined these views and provided the first articulation of the mind/body interactionism that was to elicit such pronounced reaction from later thinkers. In Descartes' conception, the rational soul, an entity distinct from the body and making contact with the body at the pineal gland, might or might not become aware of the differential outflow of animal spirits brought about through the rearrangement of the interfibrillar spaces. When such awareness did occur, however, the result was conscious sensation -- body affecting mind. In turn, in voluntary action, the soul might itself initiate a differential outflow of animal spirits. Mind, in other words, could also affect body. ...