It appears to me that the subject of music, from Machaut to Boulez, has always been its construction. Melodies of 12-tone rows just don't happen. They must be constructed.... To demonstrate any formal idea in music, whether structure or stricture, is a matter of construction, in which the methodology is the controlling metaphor of the composition... Only by 'unfixing' the elements traditionally used to construct a piece of music could the sounds exist in themselves—not as symbols, or memories which were memories of other music to begin with.

quoted in Classic Essays on Twentieth-Century Music, ISBN 0028645812