Persian Surgery Dervishes represents the height of Riley’s 1970s style. The work is based on a drone on C around which the first five intervals of the C-minor scale sail windily. The basic riff was developed in the 1960s in his Keyboard Study No. 2. In Persian Surgery however it is set within a richer and more resonant aural landscape, partly the result of his beefy Vox Supercontinental Combo organ and partly because of his doubling of the musical lines. One of the things that marks this work out in the development of Minimalism is Riley’s use of melody, which is fertile and free-flowing and unfolds in rhythms that allow it to clash with the five-note figurations in the left hand. His study of the vocal music of the North Indian vocal master Pandit Pran Nath – to whom La Monte Young had introduced him - finds its fruits in this work.