Wystan Hugh Auden (21 February 1907 – 29 September 1973), who published as W. H. Auden, was an Anglo-American poet, born in England, later an American citizen, and is regarded by many critics as one of the greatest writers of the 20th century. His work is noted for its stylistic and technical achievement, its engagement with moral and political issues, and its variety in tone, form and content. The central themes of his poetry are love, politics and citizenship, religion and morals, and the relationship between unique human beings and the anonymous, impersonal world of nature. Auden took a particular interest in writing opera librettos, a form ideally suited to direct expression of strong feelings. He wrote the libretto for Britten's operetta Paul Bunyan and with Chester Kallman co-wrote the librettos for Stravinsky's The Rake's Progress, Nicolas Nabokov's Love's Labour's Lost, and two operas by Hans Werner Henze—Elegy for Young Lovers and The Bassarids.