This paper attempts to clarify the growing process of the dynamic totality of K. Mannheim's social theory, and further, to show the effectiveness of his conception of the completed form of this totality, the “Principia Media”, employed in the explanation of social planning and the formation of human character. The term “principia media” has various meanings; among others, the most important one is that of mediating between the abstract (interpretation) and the concrete(practice).It will be showed that he tried to integrate nominalism and conservative substantialism on the epistemological level.