When a composer admits that one of his more "famous" pieces has no identifiable content, you know you're in for an uphill climb whether you choose to study their works, perform them, or just listen to them.
John Cage replaces the comforting order of the cosmos with the recalcitrant, indecipherable organization of a part of the universe. Each sound, radically set off from the others, demands that we hear it in isolation.
If Nicholls can only describe the shadow of the event, the echo of the song, then it is to his credit that he succeeds. The book places these experimental pieces in a context outside of the assumed joke or prank.