Except in a vacuum, silence does not exist. Outside laboratory conditions, perfect sine tones and absolute white noise can't be found. The harmonic series is another elegant conceptual construction that we believe should exist. We hear portions of the harmonic series all the time, in our musical instruments and occasionally in the larger world around us. But we never hear it in full, mathematically pristine form.

The harmonic series, sine tones, white noise, absolute silence: these ideals of sound tantalize the mind's ear. But the world is richer, subtler, more nuanced and more complex than we imagine. Almost nothing we hear conforms to the patterns we construct.

-- John Luther Adams, from "A Composer's Journal, Part II–Studio Notes," February 9, 2005 The Place Where You Go to Listen