Atonality Out of Necessity

"The method of composing with twelve tones grew out of a necessity. In the last hundred years, the concept of harmony has changed tremendously through the development of chromaticism. The idea that one basic tone, the root, dominated the construction of chords and regulated their succession—the concept of tonality—had to develop first into a concept of extended tonality. ...[I]t became doubtful whether a tonic appearing at the beginning, at the end, or at any other point really had a constructive meaning. ...In this way, tonality was already dethroned in practise, if not in theory." (Style and Idea, Arnold Schoenberg, "Composition with Twelve Tones".)

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