The human being, like every living thing, is an instrument for the building up and discharge of energy. He takes in food, the food is digested (made over into certain substances) and these are built up into the tissues,--and then their energy is discharged as heat and as motion. The heat is the body temperature, the motion is the movement of the human body in all the marvelous variety of which it is capable. In other words, the discharge of energy is the play of our childhood and of our later years; it is the skill and strength of our arms, the cleverness of our hands, the fleetness of our feet, the joyous vigor of our love-making, the embrace; it is the noble purpose, the long, hard-fought battles of any kind. It is all that is summed up in desire, purpose, and achievement. Now all these things may be impeded by actual reduction of energy, as in tuberculosis, cancer, or in the lassitude of convalescence. In addition there are emotions, feelings, thoughts that energize,--that create vigor and strength of body and mind. Joy rouses the spirit; one dances, laughs, sings, shouts; or the more quiet type of person takes up work with zeal and renewed energy. Hope brings with it an eagerness for the battle, a zest for work. The glow of pride that comes with praise is a stimulus of great power and enlarges the scope of the personality. The feeling that comes with successful effort, with rewarded effort, is a new birth of purpose and will. And whatever arouses the fighting spirit, which in the last analysis is based on anger, achieves the same end. There are _deënergizing emotions and experiences_ as well, things that suddenly rob the victim of strength and purpose. Fear of a certain type is one of these things, as when one's knees knock together, the limbs become as it were without the control of the will, the heart flutters, and the voice is hoarse and weak. Fear of sickness, fear of death, either for one's self or some beloved one, may completely deënergize the strongest man. Then there is hope deferred, and disappointment, the frustration of desire and purpose, helplessness before insult and injustice, blame merited or unmerited, the feeling of failure and inevitable disaster. There is the unhappy life situation,--the mistaken marriage, the disillusionment of betrayed love, the dashing of parental pride. The profoundest deënergization of life may come from a failure of interest in one's work, a boredom due to monotony, a dropping out of enthusiasm from the mere failure of new stimuli, as occurs with loneliness. Any or all of these factors may bring about a neurasthenic, deënergized state with lowering of the functions of mind and body. We shall discover how this comes about farther on. What part does a subconscious personality take in all this and in further symptoms? Is there a subconsciousness, and what is it?