The idea of the present study is basically a simple one. It attempts to reconcile the concept of social evolution with that of the structural unity of Man, an idea that is becoming increasingly dominant in the exact as well as in the social sciences. The idea of structure as it emerges from the social field is applied to the human mind as the ultimate cause of society. While pragmatism interpreted the mind as reacting as a whole, the concept of structure places the relation of Man versus his Environment in a different light, and attempts to determine the possible limits of social development. These problems are analyzed in a number of introductory chapters while the basic approach is illustrated by an analysis of some aspects of the growth of Western civilization. Some fictitious "case-studies" have been added in order to leave room for an imaginative interpretation which sometimes can bring out points which are more difficult to explain in "objective" language.