One of the innovations most responsible for the success of The Beggar’s Opera was Gay’s setting new lyrics to old tunes drawn largely from ballads—cheap songs circulating orally and through print on a dizzying range of topics, some of them centuries old (“Chevy Chase”) and others quite new (“The South Sea Ballads”). In one sense, Gay was following prior practice; new words for old tunes was built into ballad practice, sometimes simply to draw the audience in with a familiar bit of music and other times to add to the effect by setting lyrics that contrast with the reputation of the tune. For instance, religiously-minded authors adapted secular tunes in attempt to draw in potential converts. This section will contain examples and discussions of Gay’s musical sources—not only ballads but also Italian opera.
For more on ballad music, see this brief but informative essay on the University of California Santa Barbara’s excellent broadside ballads site.