"Popular art" has a number of meanings, impossible to define with any precision, which range from folklore to junk. The poles are clear enough, but the middle tends to blur. The Hollywood Western of the 1930's, for example, has elements of folklore, but is closer to junk than to high art or folk art. There can be great trash, just as there is bad high art. The musicals of George Gershwin are great popular art, never aspiring to high art. Schubert and Brahms, however, used elements of popular music – folk themes – in works clearly intended as high art. The case of Verdi is a different one: he took a popular genre – bourgeois melodrama set to music (an accurate definition of nineteenth-century opera) – and, without altering its fundamental nature, transmuted it into high art.