Glass, Philip (1937-...), is an American composer. His works combine elements of rock music, the music of Africa and India, and classical Western music. In the late 1960's, Glass and fellow American composers Steve Reich, La Monte Young, and Terry Riley began to compose in a style called Minimalism, which uses repeated short patterns of music with simple harmonies and occasional variation. Typical is Glass's repetitious, hypnotic Music in 12 Parts (1974), which lasts four hours.