 This orientation brings along with it the importance of analyzing closely the social and natural environment in which actors frame their choices. A historian’s account of the flow of human action eventuating in historical change unavoidably needs to take into account the institutional and situational environment in which these actions take place. Part of the social environment of a period of historical change is the ensemble of institutions that exist more or less stably in the period: property relations, political institutions, family structures, educational practices, religious and moral values. So historical explanations need to be sophisticated in their treatment of institutions, cultures, and practices. It is an important fact that a given period in time possesses a fund of scientific and technical knowledge, a set of social relationships of power, and a level of material productivity. It is also an important fact that knowledge is limited; that coercion exists; and that resources for action are limited. Within these opportunities and limitations, individuals, from leaders to ordinary people, make out their lives and ambitions through action.