Gruppen ("Groups") for three orchestras (1955-57) is amongst the best-known works of German composer Karlheinz Stockhausen. In it, a large group of 107 players is divided into three orchestral units, each with its own conductor, which are deployed in a horseshoe shape to the left, front, and right of the audience. The spatial separation was principally motivated by the compositional requirement of keeping simultaneously played but musically separate passages distinct from one another, but led to some orgiastic passages in which a single musical process is passed from one orchestra to another.