I like to think of the Chord Catalogue as a sort of natural phenomenonæsomething which has always been present in the ordinary musical scale, and which I simply observed, rather than invented. It is not so much a composition as simply a list.
Tom Johnson , 1985

Extreme and, one would think, extremely simple. A lesser man would have arranged those 8178 chords in some symphonically meaningful, or else quasi-random order, but Johnson proceeded methodically up the chromatic scale from two notes at a time, three, four, so on to 13. Before each section he would disconcertingly inform us, "the 715 four-note chords... the 1287 five-note chords..." His modest promise that we would "get the idea of the piece" within a few minutes wasn't really true. Two-note chords were predictably dull, three-note ones little better.But four notes began to sound almost like functional tonality in this denuded context: five sounded noticeagbly lusher, and reminded one of the era in which harmony was enriched by ninth chords and similar possibilities. By the time we reached 10-note chords, the information overload was such that differences were hardly perceptible, a situation reminiscent of serial music. Far from being heavy-handed minimalism, the Chord Catalogue was a pointed lesson in musi!c history and the relativity of perception.
Kyle Gann, Village Voice (April 14, 1987)

Another transcendental experience was Tom Johnson's Chord Catalogue, which included all the 8178 chords possible in the octave c - c1, from the two-note chords to the complete cluster. Johnson, who required only one hour for this, is the only pianist who can make his way through the dizzying multiplicity of colors present in the equal-tempered scale. Resonances in the space, and excitations in the ears, caused sheer psychedelic perceptions, that well surpassed the simple combinations game.
Matthias Entress, Berliner Morgenpost. Nov. 24, 1998