Germany's urban centers in the 1920s and '30s were buzzing with jazz clubs, cabaret houses and avant-garde music. In contrast, the National Socialist regime made concentrated efforts to shun modern music (which was considered degenerate and Jewish in nature) and instead embraced classical German music. Highly favored was music which alluded to a mythic, heroic German past such as Johann Sebastian Bach, Ludwig van Beethoven and Richard Wagner. Anton Bruckner was highly favored as his music was regarded as an expression of the zeitgeist of the German volk. The music of Arnold Schoenberg (and atonal music along with it), Gustav Mahler, Felix Mendelssohn and many others was banned because the composers were Jewish or of Jewish origin. Paul Hindemith fled to Switzerland in 1938, rather than fit his music into Nazi ideology. Some operas of Georg Friedrich Händel were either banned outright for themes sympathetic to Jews and Judaism or had new librettos written for them. German composers who had their music performed more often during the Nazi period were Max Reger and Hans Pfitzner. Richard Strauss continued to be the most performed contemporary German composer, as he had been prior to the Nazi regime. However, even Strauss had his opera "The Silent Woman" banned in 1935 due to his Jewish librettist Stefan Zweig.