The end of the Neolithic age betokens almost as universal a re-orientation of life, almost as profound a revolution of economy and society, as its beginning. Then the break was marked by the transition from mere consumption to production, from primitive individualism to co-operation, now it is marked by the beginning of independent trade and handicrafts, the rise of cities and markets, and the agglomeration and differentiation of the population.

The Social History of Art, Volume I. From Prehistoric Times to the Middle Ages, 1999 - Chapter II. Ancient Oriental Urban cultures