This chapter shows that psychic causes may play and the prevention a great role in the occurrence of disease. It also shows that without the presenceof a psychic component which invokes the disease hardly a single case of nervous disease could occur. The psychological study of disease is still a very young and immature science. The influence of emotional disturbance upon "nervous" diseases has only recently received careful study. Inordinate ambition, which foolish parents kindle in their children's hearts, is often the cause of an early breakdown. Human beings sicken so often, and madness increaseswith such uncanny rapidity, because our most secret wishes are never gratified, because in these dull times the miraculous has died, and becauselife demandsso much renunciation and yields so little happiness.