CHOICE – in conventional composition (such as Cage's early Nocturne), the composer's task is primarily one of making choices – choosing the right pitch, the right harmony, the right rhythm. In Six Melodies, Cage was still making choices, although after the initial decisions of rhythmic STRUCTURE and pitch GAMUT were made, the composer's options were considerably more restricted.  In later works, the act of composition becomes one of creating macro-structures which accept MATERIAL determined largely by CHANCE (through techniques such as IMITATION or the DUCHAMP TRAIN) or by choices made by the PERFORMER, as in the late NUMBER pieces.