A trance music piece (1974) made up of repeating 4/4 cells in which an absolutely steady eighth-note motion predominates. Often several cells are going on simultaneously, and one cell frequently mutates into another through the addition or subtraction of a note or two. One has to step back far enough to get a perspective on the large-scale shifts in density and tonality before the impact of An Hour For Piano can be felt. Frederic Rzewski plays very percussively throughout, giving the piece an intense forward motion.