since wagner, the use of leitmotifs has been taken up by many other composers. richard strauss used the device in many of his operas and several of his symphonic poems. despite his sometimes acerbic comments on wagner, claude debussy utilized leitmotifs in his opera "pelléas et mélisande" (1902). arnold schoenberg used a complex set of leitmotifs in his choral work "gurre-lieder" (completed 1911). alban berg's opera "wozzeck" (1914–1922) also utilizes leitmotifs. the leitmotif was also a major feature of the opera "the immortal hour" by the english composer rutland boughton. his constantly recurrent, memorably tuneful leitmotifs contributed in no small way to the widespread popularity of the opera.