Instincts are the natural resources of human behavior,the raw materials of action,feeling,and thought.They are the primary motives and the indispensable instruments of action.But like other natural resources,men"s original tendencies must be controlled and redirected,if they are to be frurtfully utilized in the interests of human welfare.There are a number of conditions that make imperative the control of native tendencies.The first of these is intrinsic to the organization of instincts themselves:impulses are stimulated at random and collide with one another.（46）Often one impulse,be it that of curiosity or aggression,can be indulged only at the expense or frustration of many others just as natural,normal,and inevitable.A life is a long-time enterprise and it contains a diversity of desires.If all of these are to receive any measure of fulfillment there must be compromise and adjustment between them;they must all be subjected to some measure of control.A second cause for the control of instinct lies in the fact that people live and have to live together.The close association which is so characteristic of human life is partly attributable to a specific gregarious instinct,partly to the increasing need for cooperation which marks the increasing complexity of civilization.But whatever be its causes,group association makes it necessary that men regulate their impulses and actions with reference to one another.Endowed as human beings are with more or less identical sets of original native desires,the desires of one cannot be freely fulfilled without frequently coming into conflict with the similar desires of others.Still another imperative reason for the control of our instinctive equipment lies in the fact that instincts as such are inadequate to adjust either the individual or the group to contemporary conditions.They were developed in the process of evolution as useful methods for enabling the human animal to cope with a radically different and incomparably simpler environment.While the problems and processes of his life and environment have grown more complex,man"s inborn equipment for controlling the world he lives in has,through the long history of civilization,remained practically unchanged.And,finally,so vastly complicated have become the physical and the social machinery of civilized life that it is literally impossible to depend on instincts to adjust us to an environment far different from that to which they were in the process of evolution adapted.In the light of these conditions men have found that if they are to live happily and fruitfully together,certain original tendencies must be stimulated and developed,others weakened,redirected,and modified,and still others,within limits possibly,altogether repressed.