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In page Angst:

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Existential angst makes its appearance in classical musical composition in the early twentieth century as a result of both philosophical developments and as a reflection of the war-torn times. Notable composers whose works are often linked with the concept include Gustav Mahler, Richard Strauss (operas Elektra and Salome), Claude Debussy (opera Pelléas et Mélisande, ballet Jeux), Jean Sibelius (especially the Fourth Symphony), Arnold Schoenberg (A Survivor from Warsaw), Alban Berg, Francis Poulenc (opera Dialogues of the Carmelites), Dmitri Shostakovich (opera Lady Macbeth of Mtsensk, symphonies and chamber music), Béla Bartók (opera Bluebeard's Castle), and Krzysztof Penderecki (especially Threnody to the Victims of Hiroshima).[citation needed]