Most innovations discussed in the preceding chapters stemmed from composers outside the Viennese School. The division thus arising in this book between (extended) tonal and atonal music is not a matter of principle. There are two reasons for discussing atonality separately. On the one hand, the movement presented a fairly closed entity, and its line of development in the first half of the twentieth century is clearer to follow than that of any other trend. On the other hand, and here lies the main reason, the innovations of atonality were not only more radical but also more comprehensive. In the light of more recent developments, the question even arises whether this development did not offer the greatest opportunity for a future synthesis of all innovations of the first half of the twentieth century. Whatever the case may be, this tendency was evident, and the fact that many composers consequently hovered on the edge of a (musical) abyss is a side effect that can only disturb those who are too cautious.

THE DEVELOPMENT TOWARDS FREE ATONALITY. The disintegration of the sense of tonality, and the corresponding dispersal into elements, brought the following aspects to the fore:

• 1. Musical elements that were once secondary, subordinated to tonal form categories of a higher order, became autonomous;

• 2. The lack of tonal coherence called for the pursuit of a unity that could bind the dissociated musical language in another manner;

• 3. New concepts of form arose, partly due to the replacement of diatonic principles of structure by chromatic ones.

• 1. Autonomy. The manner in which rhythm became autonomous has already been sufficiently discussed. Released from its metrical context, it developed into the floating rhythm and autonomous rhythmic structures of Stravinsky and Messiaen.

In the Viennese School, however, the emphasis lay on pitch structure. With regard to melody and harmony, the disintegration of the classical diatonic scale created a whole new range of problems. That Vienna formed the stage for this was largely thanks to expressionism, which viewed chromaticism in particular as a powerful means of expansion.