It was fun to puzzle through Cage's mystical tone of writing, as well as through why I feel opposed to certain of his claims. Moreover, at some parts, Cage articulates what he sees is the heart of new/experimental music. (A disclaimer: I'm no musician or composer, but enjoy listening to new music. So my sense-making of Cage's work is limited by my lack of background knowledge of his field.) This is what I took away from this positive side: Before new music, composers have worked within sound, making pieces that are beautiful, without concern or perhaps awareness of the fact that their works consist in solely sounds, and thereby without inquisitiveness into the possibilities of sound. New music is founded on precisely this awareness and inquisitiveness. Music, noise, and silence are all equally sounds, and recognizing this brings one closer to getting a grip on the phenomenon of sound itself. What is sound itself, and why does this matter? Cage has a fun thing to say: sound "is Buddha," or a Western version of this might be that sound "is Christ." What the heck is that supposed to mean? Cage is never direct about this, but a reader may pick up that "Buddha," in this context, for Cage stands in for the (simplified) Buddhist idea that everything is empty (i.e., all possible things we encounter are always mediated by our conceptual repertoires and cognitive systems, so nothing is truly as it appears; moreover, everything we encounter constitutionally depends on everything else, via a metaphysics of interconnectedness, so the appearance that things are self-standing individuals is illusory, too), and with this realization, one may go about all that one usually experiences with a newfound distance or lightness of touch. I've studied a bit of Buddhist philosophy, and it is interesting to see an American composer so devoted to this school of thought, and to make sense of the power of the artist/composer in light of it. So I guess Cage's obsession with the sound 'itself' is connected to his spiritual practice of forgetting about the imaginings and thoughts that one typically projects upon sound, when one senses it to be music v. noise for example, so that one can have a double book keeping on both that meaning-based projection realm, and the realm of the bare sound.
There's one more positive point that Cage gives, which I found particularly helpful for approaching new music. Much of new music is atonal: its sounds don't flow according to any particular key, of the traditional 12-tone system, but constantly slides between potential keys. Music must have structure in order to be engaged with as music (I don't know how to elaborate on / defend this point, but Cage presupposes it). So the tasks of the contemporary composer is to find other ways to structure a piece, other than the tone of a key. In other words, the composer is freed from the structure of tonality, and so now has the chance to find new ways that may structure sounds, as to push the horizons of the possibilities of music.
I usually don't like obscure writing that aims to be mystical (i.e., it is purposefully confusing or obscure in order to convey some higher spiritual truth, that purportedly simply could not be given to the reader if language were used straightforwardly), but I found quite a lot of what Cage had to say, under this style, interesting and fun to think through. I get the impression that he is indeed a deep thinker, which allows him to write successfully in this way.
In one essay, Cage writes about his piece "Music for Piano 21-52." Like other pieces, he uses a method to randomize his compositional choices, and moreover the finished manuscript only specifies for the performers/conductor the timbre and rhythmic structure of the piece. Other crucial variables that are usually specified in a composition (e.g., architecture of the room in which the performance is given, placement of the instruments, how many instruments) are omitted. Cage then asks "All these elements, evidently of paramount importance, point the question: What has been composed?" I had fun thinking about this. It seems to me that such a piece would serve to bring people together, and to give them just enough infrastructure to allow for performers to be coordinated with one another. Perhaps this could be an analogy: induce some overall bodily/affective state in everyone of a group, like making them excited, so they are affectively attuned to one another, and see what communication flows from that, and what particular emotions each ends up in. Moreover, this makes explicit or leans into the fact that music is always temporal, singular to the moment. There will be differences between each performance of any composition, no matter how detailedly specified it is. Cage's piece here seems to allow for the unique conditions of the present to create the piece. I guess all of this would hold for musical improvisation as well, however, so I'm unsure how this piece relates to improv. At least it deviates from improv in offering performers a score that is supposedly free from all human intention, culture, and tradition (Cage tries to achieve this through his randomization methods, such as by using the I-Ching).
This leads me to the point of disagreement I have with Cage. Cage believes that new/experimental music ought to break ties with all history of aesthetics/music, and aim at transcending any influence that the composer's individual character or psychology might bring. Why? Cage thinks that the present goal of music should be to create new sounds, qua sound itself; it's a particularly fertile time to do this, in light of the invention of computer technologies. Cage believes that this is more readily achieved in a naivete or disregard of history. He even explicitly says that budding composers need not listen to Bach or Beethoven. This seems horribly wrong. All of us, composers and music-listeners alike, are embedded in history. History will inevitably shape what choices a composer makes, and how a listener will hear and interpret a sound. So in order to most powerfully express something musically, one must know about this history, e.g., this enables one to know how listeners will receive something one marks out, or to see the significance of a particular choice, in light of its contrast or relation to other things done in the past.
This brings me back to thinking about what is meant in that music should aim to deliver sound itself (e.g., music, noice, and silence), and to explore the possibilities of sound. However Cage meant this, he must've thought that a disregard for history would be conducive towards this goal. This suggests that he thinks that "sound itself" is a-cultural and a-historical; perhaps he thinks of it as a pure sensory phenomenon, like color sensations, which are universally experienced (as opposed to some perceptual experience that involves more than just sensations, but also the work of the imagination; bringing in interpretation, meaning, symbolism, etc.) But it'd be quite odd for an artist to think that all of music ought to aim at such a narrow goal, to eliminate humanly imposed meaning, and to bring us back to conceptless bodily sensation. That seems restrictively ideological, to say the least.
I'd be curious to hear from someone who knows more the extent to which Cage has influenced new music, and whether his ideology has been taken up, or how people have responded to or challenged it. I can imagine that his ideology could be useful for people to challenge, for inspiring new thought: maybe there are new ways to aim to express oneself, or to disclose culturally-relevant meaning, after some naive way of doing so has been razed to the ground.