Morton Feldman is a pupil of Wallingford Riegger and Stefan Wolpe. Feldman was in a circle that revolved around John Cage during the ‘50s. Early in his career he developed a graphic notation that indicated relative durations but allowed the player to choose the pitches within a given register; or the pitches might be specified but the durations left to the performer. Later, he began to produce his very long works, often in one continuous movement, rarely shorter than half an hour in length and often much longer. These works include Violin and String Quartet (2 around hours), For Philip Guston (around four hours) and the String Quartet II (over six hours long without a break.) These pieces tend to be made up of very quiet sounds. Feldman said himself that quiet sounds had begun to be the only ones that interested him.