The pineal neurophysiology of the passions or emotions is similar to what is occurring in perception: “the ultimate and most proximate cause of the passions of the soul is simply the agitation by which the spirits move the little gland in the middle of the brain” (AT XI:371, CSM I:349). However, there are some new ingredients which have no parallel in the Treatise of man. For example, in a chapter on the “conflicts that are usually supposed to occur between the lower part and the higher part of the soul,” we read that “the little gland in the middle of the brain can be pushed to one side by the soul and to the other side by the animal spirits” and that conflicting volitions may result in a conflict between “the force with which the spirits push the gland so as to cause the soul to desire something, and the force with which the soul, by its volition to avoid this thing, pushes the gland in a contrary direction” (AT XI:364, CSM I:345).