The, twentieth century has witnessed changes that in frequency and magnitude are unmatched in any previous musical history. The diversity of trends, styles, and techniques preclude the possibility of, studying art music as one coordinated whole, as historians have generally tried to do with it before this century. Further, we lack the necessary distance from the events to analyze fully our understanding of twentieth century musical history. Composers of art music out of the Western tradition are now to be found throughout the world, making discussion of the music against a backdrop of merely European history and society impossible.