The evolution of twentieth century American music involves much more than the continuation of European tradition. The music of black Americans before and after the turn of the century had a profound impact on the musical sensibility of American culture in general. Additionally, the fledgling popular music publishing industry had a dramatic effect on the course of "classical" tradition. Nowhere was this more apparent than in the music of George Gershwin. Gershwin's importance in the history of American art music is undisputed. Why his music sounds the way it does is less understood. This paper considers the popular and folk genres that most influenced the young caiposer, and traces specific stylistic elements through their various popular and folk incarnations of the previous thirty years into Gershwin's Rhapsody in Blue of 1924.

This dissertation focuses on the first Parable of Vincent Ludwig Persichetti, written for alto flute in 1965. Persichetti spent from 1965 to 1986 (almost the last twenty years of his life) composing twenty-four additional Parables for various solo instruments, instrumental combinations, and even one in the form of an opera.