Four6 sounds radical, though it's late. There are no pitches and instruments specified in the score. The four performers are told to choose 12 different sounds with fixed characteristics (amplitude, overtone structure etc.) The score tells each performer when the performer should begin to play, and when he should end. Or rather, in this piece, he gives them a range of times to start and end. Here's the first page for the first performer

And here for the fourth

(The diagonals mean that the sounds should be close to each other.)
The first point I want to make is that this type of score seems to defy analysis and defy criticism. Cage appears to have constructed the score carefully, with some attention to details, but how? Are the composer's decisions made randomly or is there a system or what? And how are we to say whether this is a good piece of music? Or even one of the better number pieces?
And the second point I want to make is that
prima facie we see a huge demand on player creativity here - compared with the rails of
Music of Changes and
Variations II, where the chance operations result in a score which completely controls the sounds the performers make.
But things may not be so simple. How does each player decide what to play, when to play it and for how long? Cage is silent about this. Should the player use judgements of taste? Or should the performer also be guided by random processes as Cage was in the music constructed by chance processes? This is, after all, not a graphic score or a even a work like
Song Book.

The above recording of
Four6 is made using recording technology by one person, Sabine Liebner is
auteur. It's a one woman show. Is that a good idea? Or are these pieces a metaphor for anarchy, in the sense of an
ensemble where each person is free to do as he sees fit in the whole? Does she address this in the booklet? I don't have it (it's on Qobuz)
There are many other recordings of
Four6, and I certainly would be unable to pick out in any interesting way the salient features which make one different from another. All provide attractive meditative surfaces.