Subaruguru: Historicity is not in the sense of sucessive events through time. But rather as a means in which within a specific tradition (ie Romanticism) an occurrence of the qualitatively new transpires; it is not a movement through time in which there is mere identity or reproduction of what has always been, but rather one in which the new occurs (ie chromaticism of Wagner or Mahler). Of course this is mediated by its opposite, the term "nature", which is being or "sein" as predetermined, in "essence" it is the "substance" within history. It is static, timeless and unchanging. However after reading the works of Adorno, the triple threat of musicologist, dialectical philosopher, and marxist sociologist, Nature or "natural" is not static or timeless as mediated through its opposite, history. If you take one of Adorno's pet topics: musical materials, and using his dialectical process you see that nature is nothing more than myth. If you take something that is "natural" within music say, tonality, one can dialectically say that it is myth, because historicity changed tonal systems because chromaticism changed it, serialism changed it, and atonality changed it, polystylism changed it. The tonal system is still here, it is used in the music culture industry(ie the inclusive term of popular music) but has lost its truth content, maybe 100 years ago. No contemporary classical composer worth his salt would ever use the tonal system other than as kitsch. As a pianist, you know one true and tried method of expression, is the use of the augmented or the diminished seventh as used by Beethoven. But by the middle of the century, no composer would ever dare use the seventh again because its truth content was musically nontruth. You could use this nontruth in a kitsch sort of way, like Schnittke, as a wink and a nod, or as satire or irony, but as an expressive musical material, as an "object in its self" it is relegated to the dust bin of music.
