The eighteenth centuries are reasonably described as an era of musical common practice, when composers of different nationalities and temperaments nonetheless wrote music that was stylistically and structurally similar in important respects. however, in contrast, the twentieth century has been a period of great and increasing diversity of both style and structure. More specifically, music criticism has divided twentieth century music into two opposing groups; the neoclassical and the progressive.This view has remained influential up to the present day. It depicts the neoclassicists (especially Stravinsky) as attempting to restore and revive aspects of earlier music while the progressive (Schoenberg, Berg and Webern) pushed music forward in a direction determined by the historical developments of late nineteenth century chromaticism. Neoclassical music is seen as relatively simple, static,and objective as having revived the classical ideals of balance and proportion. But Progressive music is seen as relatively complex, developmental, and emotionally expressive as having extended the tradition of romanticism. Stravinsky realises and asks himself,"Was I merely trying to refit old ships while the other side - Schoenberg - sought new forms of travel?" the answer seems to be 'YES'. Schoenberg has found new forms of thravel which was the methode of composing with twelve tones, as we call it, 'Serial music'.
For Schoenberg, progress was what history requires. Music is in continuous process of evolution. It is the composer's task to comprehend the historical trend and to keep it going in the proper direction. Schoenberg mentions,"While composing for me had been a pleasure, now it became a duty. I knew I had to fulfil the task; I had to express what was necessary to be expressed and I knew I had the duty of developing my ideas for the sake of progree in music, whether I liked it or not." Webern spoke of a similar sense of compulsion and of the weight of the past pushing him: "and never in the history of music has there been such resistance as there was to.