Parsons' theory of societal evolution -- Primitive societies: the emergence of social stratification -- Archaic societies: legitimation by a literate priesthood -- The historic empires: further differentiation of the society from its legitimate cultural system -- Cultural legacies for later societies: the Hebrew and Greek concepts of a moral order -- The religious legitimation of secular society -- The emergence of national communities -- Further differentiations in the age of revolutions -- The central problem of modern societies: integration -- The differentiated system of modern societies -- Continuing evolution.