Arnold Schoenberg
. . . there is the proposition that the system of major-minor tonality is no necessity of music, no natural law -- even if it is partially founded upon the natural laws of harmonics; it is rather a convention, once viable, now exhausted, now undoubtedly to be modified or replaced by other conventions, perhaps by 'tonalities' of twelve tones.
Roy E. Carter, Translator's Preface, Arnold Schoenberg, Theory of Harmony, University of California Press, Berkeley, Los Angeles, 1911 by Universal Edition, Vienna as Harmonielehre, This translation, based on the Third Edition (1922), first published in 1978, page xv