In an essay on popular music's history for "Collier's Encyclopedia" (1984), Robert Christgau explained, "Some sort of popular music has existed for as long as there has been an urban middle class to consume it. What distinguishes it above all is the aesthetic level it is aimed at. The cultural elite has always endowed music with an exalted if not self-important religious or aesthetic status, while for the rural folk, it has been practical and unselfconscious, an accompaniment to fieldwork or to the festivals that provide periodic escape from toil. But since Rome and Alexandria, professional entertainers have diverted and edified city dwellers with songs, marches, and dances, whose pretensions fell somewhere in between."