The subject of human behavior may seem vague and indefinite to the man of science who is accustomed to dealing with specific phenomena. This is in large part due to the fact that human behavior is an expression of the most complex organization in the world. There are so many implications in human behavior that individual aspects of it have been developed into separate and distinct sciences, such as psychology, sociology, economics, etc. Moreover, the medical man entering this field is confronted with the necessity of considering facts and points of view which are more or less foreign to medicine. This gives rise to the appearance of disharmony if not of direct opposition among those who work on the problem. Fortunately, there is no real clash between the various departments of science. There need be no attempt to supplant the older professions which have dealt with the behavior problem; on