John Cage is one of the musicians who has always existed on the periphery of my little musical world. It was only during university in 20th Century Art Music class that I discovered his works and just how subversive they are.
I doubt that I have ever heard a musician whose works are both inspirational, confrontational and yet repellent all at once (except maybe Captain Beefheart). His music can be challenge the way you perceive music and musical ideas, and it can also make some people want to smash things.
The word that is largely associated with him is "visionary". Indeed, he tried hard to break the mold of conventional music concepts by breaking as many rules as possible. By working in areas of sonic territory that were previously uncharted, he'd made numerous advances in musical discovery, particularly in the field of electronic music. By also adding the previously unheard of element of "chance" to musical composition, he created music that is random and never predictable.
Visionary, in the sense that he changed the way a piano sounds in order to emphasise the percussive nature of the instrument. After all, a piano has hammers that strike strings, right? But instead of it being a melodic instrument in his mind, he brought out the percussive nature of it, by altering the tones of the strings by putting erasers and nails and screws and pieces of fabric in the strings, thus disallowing the strings to "ring out" as they normally would. This he called the prepared piano.
His most notorious piece, however, was 4'33. A piece that was complete silence. A person sits at the piano, and lifts the lid, puts the lid down, lifts the lid again, and then walks off.
How stupid, I hear you say. Well, really, the jokes on you. Because, so often we listen to music to hear a tune, or a beat. We don't really listen to the sounds around us, which, when they combine and collide together, can actually make some beautiful noises. Every time 4'33 is played, the music will be different, because of the different environment you are in at the time!
He experimented with radio sounds.
He used the orchestra in unusual ways. He played 2 or more pieces together, to create a colliding soundscape that would be different every time it is played.
He really turned the music world upside down and on its head. For that I am greatful. We need more people like that to challenge the status quo of the music world.