This work comprises four books, each containing eight etudes. Cage used tracings of star charts to determine rhythm and pitch, and I Ching chance operations for all other parameters, i.e. bowing style, dynamics, durations, microtones, etc. The etudes are written in an extremely detailed way, with nearly every aspect of sound and sound production specified for each note. Thus, they are extremely difficult to perform. In performing them, Cage asked that the player simply try to play as many notes as possible. It was Cage’s purpose to make these etudes as difficult as possible in compliance with the dictum behind this composition, “Practicality of the impossible.” The first sixteen etudes were composed in collaboration with Paul Zukofsky between 1977 and 1980. Cage left them unfinished for nine years, but after hearing a performance of them by Irvine Arditti, he continued his work in 1989–90, greatly assisted by James Pritchett, who reconstructed the compositional process from Cage’s notes and worksheets.