In the last years of his life, John Cage wrote a great many so-called ‘Number Pieces’ – the title indicating the number of performing musicians.

While most of these pieces indicate which instruments are to be played, as well as the sounds that are to be produced, other pieces offer only general tone descriptions or a framework for choosing the tones oneself. What these pieces do have in common is time-organisation: Cage designates the bar within which the tones must be played.

Should one play these sound-sequences within the interval quickly, then one must wait for the beginning of the next bar in order to continue; should one play with an even slowness, the separate intervals are joined without interruption.

And so, each performance of the same piece is different: in one instance an even flow of sounds, in another a pulsation of rapid responses accompanied by pauses (including all variations).

An exception is Two. Here the two pianists do not play according to a stopwatch, but rather by reacting to one another: although the piece indicates bars, it does not assign tempo or even pulse. While both interpreters play independently of each other, they may continue on to the next bar only when the other player has finished his. Cage decided on the number of tones within a bar by drawing upon the rules of Renga, Japanese linked poetry, in which the number of syllables per verse are set at 5, 7, 5, 7, 7.

As the pedal is continuously depressed, the notes sound into one another and this inner structure remains undetected.