For John Cage: "Silence is all of the sound we don't intend. There is no such thing as absolute silence. Therefore silence may very well include sounds and more and more in the twentieth century does. The sound of jet planes, of sirens, et cetera."
"By silence, I mean the multiplicity of activity that constantly surrounds us. We call it 'silence' because it is free of our activity. It does not correspond to ideas of order or expressive feeling -- they lead to order and expression, but when they do, it 'deafens' us to the sounds themselves.