Let's start with the first part of the Sonatas and Interludes for prepared piano, a piece a lot of commentors have said is their favorite Cage:
It's not Mozart! Sorry, couldn't resist. The thing is that I am not unsympathetic to Cage's aesthetic. There was a time, perhaps twenty years ago, when I was very much a Cage admirer. Though even then I found his writings ON music to be more interesting than his writing OF music. I contemplated giving a performance of some of his talks on music. I even wrote at least one piece very strongly influenced by his aesthetic. But as time went on, I'm afraid I have become an apostate of Cage's aesthetic as I don't believe it is a musical aesthetic at all. I can't quite agree with Daniel Asia when he says that "Sonatas and Interludes offers many movements that add up to no perceivable aural structure." The different movements each have a character that is largely rhythmic. Sonata IV, for example, is full of "fiveness" if I can call it that: a lot of quintuplets and time signatures involving 5.
Imagine you want a career as a modernist composer, but you have no real sense of harmony or melody. Your gifts, such as they are, lie in the area of rhythm. Writing for prepared piano, where screws and bolts alter the pitch to the point that it is really not possible to analyze the harmonic structure, is your way to avoid being evaluated in areas you are weak. It's brilliant, really! But it is a kind of aesthetic fraud. Is this what Cage did? I have no idea, I just present the possibility. Here is the second part of the Sonatas and Interludes:
When I was in my Cage phase, I can't say that I was thinking musical thoughts as such. Perhaps 'sound' thoughts or 'sonic' thoughts, but not musical thoughts as such. Cage presents, and intends to present, a huge challenge to aesthetics. But I think that the answer to the challenge is found by listening to his music. It is a simulacrum of music, to steal an idea from Baudrillard, a shadowy copy of music. One of the sonatas sounds like a horribly crippled prelude by Debussy, for example. You can listen to this music and enjoy it and have some kind of experience, but I have to agree with Daniel Asia, it is ultimately frustrating for the reasons he gives: "The emotional landscape is limited and proscribed, ultimately wan and shadowy."
The reasons for this are obvious: Cage was not writing music as such, he was creating a facsimile of music without harmony or melody, without anything but chance sounds within a rhythmic framework. Of course there is no narrative! For one of his talks, he wrote a talk, then cut it up and mixed the pieces randomly. There is not supposed to be a narrative in Cage. But writing music the way he did is to create, at best--at best--a private language, one that we are not privy to. For that reason, it fails as music. Here is part 3 of the Sonatas and Interludes:
But listen and make up your own mind, by all means. Just don't assume it is a musical success simply because everyone and his dog is putting on a John Cage concert for the centenary.