Béla Bartók’s earliest compositions offer a blend of late Romanticism and nationalist elements, formed under the influences of Wagner, Brahms, Liszt and Strauss, and resulting in works such as Kossuth, an expansive symphonic poem written when he was 23. Around 1905 his friend and fellow-composer Zoltán Kodály directed his attention to Hungarian folk music and, coupled with his discovery of the music of Debussy, Bartók’s musical language changed dramatically: it acquired greater focus and purpose – though initially it remained very rich, as his opera Duke Bluebeard’s Castle (1911) and ballet The Wooden Prince (1917) demonstrate. But as he absorbed more and more of the spirit of Hungarian folk songs and dances, his own music grew tighter, more concentrated, chromatic and dissonant – and although a sense of key is sometimes lost in individual passages, Bartók never espoused atonality as a compositional technique.

His interest is folk music was not merely passive: Bartók was an assiduous ethnomusicologist, his first systematic collecting trips in Hungary being undertaken with Kodály, and in 1906 they published a volume of the songs they had collected. Thereafter Bartók’s involvement grew deeper and his scope wider, encompassing a number of ethnic traditions both near at hand and further afield: Transylvanian, Romanian, North African and others.

In the 1920s and ’30s Bartók’s international fame spread, and he toured widely, both as pianist (usually in his own works) and as a respected composer. Works like the Dance Suite for orchestra (1923), the Cantata profana (1934) and the Divertimento for strings (1939), commissioned by Paul Sacher, maintained his high profile; indeed, he earned some notoriety when the Nazis banned his ballet The Miraculous Mandarin (1918–19) because of its sexually explicit plot. He continued to teach at the Academy of Music until his resignation in 1934, devoting much of his free time thereafter to his ethnomusicological research.

With the outbreak of the Second World War, and despite his deep attachment to his homeland, life in Hungary became intolerable and Bartók and his second wife, Ditta Pásztory, emigrated to the United States. Here his material conditions worsened considerably, despite initial promise: although he obtained a post at Columbia University and was able to pursue his folk-music studies, his concert engagements become very much rarer, and he received few commissions. Koussevitzky’s request for a Concerto for Orchestra (1943) was therefore particularly important, bringing him much-needed income. Bartók’s health was now failing, but he was nonetheless able virtually to complete his Third Piano Concerto and sketch out a Viola Concerto before his death from polycythemia (a form of leukemia) on 26 September 1945.