The Art of Fugue develops as a symbol in the book as his quartet undertakes a recording of the complete work. The idea materializes after the quartet plays Contrapunctus I as an encore. Michael, the second violinist of the quartet in "An Equal Music" described how it happened:
"I have made a small adjustment to the Tononi backstage. I now check it almost silently, and tell it not to let me down.
Normally Piers would announce the encore. Instead, he and the others look at me and nod almost imperceptibly. I begin to play. I take my first two notes on open strings, almost as if they were a transition from tuning into music.
As I play the first few slow notes I hear from different points of the dark hall the indrawn breath of startled recognition. After my four lonely bars, Piers joins me [0:16], then Billy [0:24] and then Helen [0:31].
We play almost without vibrato, keeping the bow on the string, taking open strings where they fall naturally, even if that means our phrases do not exactly replicate one another's. [...]
As I move to the tiny quaver, the minuscule quibble of a note that was the source of all my anxiety, [1:16] Helen, who has a rest here, turns her head slightly and looks at me. I can tell she is smiling. It is the F below middle C. I have had to tune my lowest string down a whole tone in order to be able to play it."
Michael refers to the second 8th of the third measure in the second violin part.
