There is, then, a marvelous reserve power in men and women which can be used in emergencies and in times of severe strain, to enable men and women to accomplish what looks impossible and which has often contradicted the prognosis of the physician. History is full of applications of this law which, however, does not come into action, unless especially called. Men and women {93} may die simply because they give up the struggle. Men and women who _will not give up_ seem able to overcome severe illness that would take away ordinary people. It has often been said that tuberculosis takes only the quitters and that men of character constitute the typically favorable patients for tuberculosis sanatoria. Psychology is now getting at the explanation of many events that were formerly quite inexplicable. The science has come to recognize the reservoir of reserve energy in human nature which may be tapped under special favoring circumstances. The physicians of the past have often succeeded in tapping it deliberately as well as unconsciously. There is large room, however, for the further development of medicine along this line, to the great advantage of therapeutics and probably the most promising field at the present time in view in therapy lies in this direction. Hence the necessity for more deliberate conscious use of it in every possible suitable form. CHAPTER II UNFAVORABLE MENTAL INFLUENCE Much as may be accomplished by psychotherapeutics through favorable mental influence--the modifying of the mental attitude towards disease, diversions of mind from aches and pains, concentration of attention on subjects apart from ailments--much more may be done by removing any unfavorable mental influence. This of itself produces symptoms either by interfering with normal processes through surveillance of them, or by so exaggerating, through attention to them, slight symptoms that may be present that patients are made quite miserable, though there is no adequate physical cause for their condition. Perhaps the most striking example that we have of unfavorable mental influence as productive of the persuasion that disease is present, is familiar to every physician who is close to medical students when they are first introduced to the symptoms of disease. It is almost a rule that certain members of the class immediately conclude that they are suffering from one or more of the symptoms which they are studying, and that, therefore, they must have the diseases with which the symptoms are associated. If at this time they walk on the shady side of a street on an autumn day and have a little shivery feeling, or when they get into the sun they feel a glow, these two very normal feelings are exaggerated into chilliness and fever, and the student has to go to his professor to have his mental malaria or typhoid treated. To the student, his symptoms are for the moment very real, and unless someone in whom he has confidence