This instinctive urge toward action arouses in the individual an organic response that is felt as a tension or craving and is mainly dependent upon its own chemical constitution at the moment.  Hunger is the sensation caused by the little muscular contractions in the stomach when the body is low in its food supply.  Sudden fright is felt as an all-gone sensation “at the pit of the stomach.”  What really happens is a tightening up of the circular muscles of the blood-vessels lying in the network of the solar plexus, and a spasm of the muscles of the digestive tract.  The hungry stomach impels to action until satisfied; the physical discomfort in fear impels toward measures of safety.  The apparatus that is made use of by the subconscious in carrying out this instinctive urge is called the autonomic nervous system.[19] It regulates all the functions of living, not only under the stress of emotion, but during every moment of waking or sleeping.

[Footnote 19:  Kempf:  “The Tonus of Automatic Segments as a Cause of Abnormal Behavior,” Journal of Nervous and Mental Diseases, January, 1921.]

=A Capable Manager.= The conscious mind could not possibly send messages to the numerous glands that fit the body for action, nor attend to all the delicate adjustments that enter into the process.  The conscious mind in most of us does not even know of the existence of the organs and secretions involved, but something sends the messages and it is something that has a remarkable likeness to mind as we usually think of mind,—­something which takes advantage of the past and gages means to an end with a nicety that excites our wonder.

=Take no Anxious Thought.= We take food into our stomachs and forget about it, if we are wise; and this subconscious overseer who through millions of years of experience has learned how to digest food does the rest.  As with digestion, so with our heart-action; we lie down at night fairly sure that there will be no break in the regular rhythm of its beat.  The subconscious overseer is “on the job” and he never rests.  No matter how hard we sleep, he never lets us forget to take a breath; and if we trust him, he is very likely to wake us up at the appointed time in the morning.  Also, if we trust him, he carries us off to sleep as though we were babies.  Has he not had long practice in the days before insomnia was invented?

=First Aid to the Injured.= In times of infection or injury, this subconscious manager is better than any doctor.  The doctors say with truth that they only assist nature.  If the infection is internal, antitoxins are produced within the body.  If the injury is external, like a cut, the messages fly, and white blood-corpuscles are marshaled to take care of poisons and build up the tissue.  If the injury is of the kind that needs rest, the subconscious doctor knows it.  He therefore causes pain and rigidity, in order to induce us to hold the injured part still until it is restored.