A statement which says that man's will is as directly based on the metabolic processes of the body, both inside and outside the muscles, as is his perceiving and thought-forming mind on a process in the nerves, is bound to cause surprise. Firstly, it seems to leave out the role commonly ascribed to the so-called motoric part of the nervous system in bringing about bodily action; and secondly, the acknowledgment of the dependence of consciousness on corporeal 'dying' implies that willing is an unconscious activity because of its being based on life processes of the body. The first of these two problems will find its answer at a later stage of our discussion when we shall see what entitles us to draw a direct connexion between volition and muscular action. To answer the second problem, simple self-observation is required. This tells us that, when we move a limb, all that we know of is the intention (in its conceptual form) which rouses the will and gives it its direction, and the fact of the completed deed. In between, we accompany the movement with a dim awareness of the momentary positions of the parts of the body involved, so that we know whether or not they are moving in the intended manner. This awareness is due to a particular sense, the 'sense of movement' or 'muscular sense' - one of those senses whose existence physiology has lately come to acknowledge. Nothing, however, is known to us of all the complex changes which are set into play within the muscles themselves in order to carry out some intended movement. And it is these that are the direct outcome of the activity of our will. Regarding man's psycho-physical organization thus, we come to see in it a kind of polarity - a death-pole, as it were, represented by the nerves including their extension into the senses, and a life-pole, represented by the metabolic and muscular systems; and connected with them a pole of consciousness and one of unconsciousness - or as we can also say, of waking and sleeping consciousness. For the degree of consciousness on the side of the life-pole is not different from the state in which the entire human being dwells during sleep. It is by thus recognizing the dependence of consciousness on processes of bodily disintegration that we first come to understand why consciousness, once it has reached a certain degree of brightness, is bound to suffer repeated interruptions. Every night, when we sleep, our nervous system becomes alive (though with gradually decreasing intensity) in order that what has been destroyed during the day may be restored. While the system is kept in this condition, no consciousness can obtain in it.