"As John Cage has insisted, 'there is no such thing as silence. Something is always happening that makes a sound.' (Cage has described how, even in a soundless chamber, he still heard at least two things: his heartbeat and the coursing of the blood in his head). Similarly, there is no such thing as empty space. As long as a human eye is looking there is always something to see. To look at something that's 'empty' is still to be looking, still to be seeing something — if only the ghosts of one's own expectations. In order to perceive fullness, one must retain an acute sense of the emptiness which marks it off; conversely, in order to perceive emptiness, one must apprehend other zones of the world as full. (In Through the Looking Glass,Alice comes upon a shop "that seemed to be full of all manner of curious things — but the oddest part of it all was that whenever she looked hard at any shelf, to make out exactly what it had on it, that particular shelf was always quite empty, though the others round it were crowded full as they could hold.")
'Silence' never ceases to imply its opposite and to demand on its presence. Just as there can't be "up" without "down" or "left" without "right," so one must acknowledge a surrounding environment of sound or language in order to recognize silence. Not only does silence exist in a world full of speech and other sounds, but any given silence takes its identity as a stretch of time being perforated by sound. (Thus, much of the beauty of Harpo Marx's muteness derives from his being surrounded by manic talkers.)
A genuine emptiness, a pure silence, are not feasible — either conceptually or in fact. If only because the art-work exists in a world furnished with many other things, the artist who creates silence or emptiness must produce something dialectical: a full void, an enriching emptiness, a resonating or eloquent silence. Silence remains, inescapably, a form of speech (in many instances, of complaint or indictment) and an element in a dialogue."
As I've tried to say before, Sontag's conception is eloquent, yet I'm not sure whether I subscribe to it or not. Silence is unsettling - this, at least, seems important. Silence is unsettling precisely because it is never purely silence. But she seems to speak of 'speech' as something nearly self-evident in itself. Might there be a 'will to silence' that resists any dialectic more rigorously than Sontag would have it?