Finally, Descartes presented an account of the origin of bodily movements. He thought that there are two types of bodily movement. First, there are movements which are caused by movements of the pineal gland. The pineal gland may be moved in three ways: (1) by “the force of the soul,” provided that there is a soul in the machine; (2) by the spirits randomly swirling about in the ventricles; and (3) as a result of stimulation of the sense organs. The role of the pineal gland is similar in all three cases: as a result of its movement, it may come close to some of the valves in the walls of the ventricles. The spirits which continuously flow from it may then push these valves open, with the result that some of the animal spirits in the pressurized ventricles can escape through these valves, flow to the muscles by means of the hollow, spirit-filled nerves, open or close certain valves in the muscles which control the tension in those muscles, and thus bring about contraction or relaxation of the muscles. As in perception, Descartes applied the term ‘idea’ again to the flow of animal spirits from the pineal gland: “And note that if we have an idea about moving a member, that idea—consisting of nothing but the way in which spirits flow from the gland—is the cause of the movement itself” (AT XI:181; Hall 1972, p. 92). Apart from the just-mentioned type of bodily motions, caused by motions of the pineal gland, there is also a second kind, namely reflexes. The pineal gland plays no role with respect to them. Reflexes are caused by direct exchanges of animal spirits between channels within the hemispheres of the brain. (Descartes did not know that there are “spinal reflexes”.) They do not necessarily give rise to ideas (in the sense of currents in the ventricles) and are not brought about by motions of the pineal gland.