Copland's brand of nationalism in his ballets differed from that of European composers such as Béla Bartók, who tried to preserve the folk tones they used as close to the original as possible. Copland enhanced the tunes he used with contemporary rhythms, textures and structures. In what could seem contradictory, he used complex harmonies and rhythms to simplify folk melodies and make them more accessible and familiar to his listeners. Except for the Shaker tune in "Appalachian Spring", Copland often syncopates traditional melodies, changes their metric patterns and note values. In "Billy the Kid", he derives many of the work's sparse harmonies from the implied harmonic constructions of the cowboy tunes themselves.