Culture has been distinguished from the other elements of action by the fact that it is intrinsically transmissible from one action system to another… - Talcott Parsons

The most promising lines of development of theory in the sociological and most immediately related fields, particularly the psychological and cultural, therefore, seem to be two-fold. One major direction is the theoretical elaboration and refinement of structural-functional analysis of social systems, including the relevant problems of motivation and their relation to cultural patterns. In this process, the structure of social action provides a basic frame of reference, and aspects of it become of direct substantive importance at many specific points. The main theoretical task, however, is more than a refinement of the conceptual scheme of the presently reprinted book — it involves transition and translation to a different level and focus of theoretical systematization.

A theoretical system does not merely state facts which have been observed and that logically deducible relations to other facts which have also been observed. In so far as such a theory is empirically correct it will also tell us what empirical facts it should be possible to observe in a given set.

A social system is a mode of organization of action elements relative to the persistence or ordered processes of change of the interactive patterns of a plurality of individual actors.