McNeill wishes to "demonstrate the feasability as well as the importance of explicitly seeking an overall interpretive scheme for European history." Such an "architectonic vision" already permeates the conventional view in the form of the growth of liberty. McNeill offers an apologia for the "grand design" approach to history and sketches an alternative "cultural pattern," his model being "metropolitan centers"; he says, "Successful innovations tend to cluster in time and space," producing a "cultural slope" of developments in technology and economics. Such centers (McNeill particularly stresses the impact of the Italian city-states) are emulated by neighboring peoples, characteristically as they — the centers — begin their own cultural decline. It is a model which has tacitly informed his work for some time; its explicit enunciation is enlightening.