Arnold Schönberg (13 September 1874 – 13 July 1951) was an Austrian composer and painter, associated with the expressionist movement in German poetry and art, and leader of the Second Viennese School. After his move to the United States in 1934, he altered the spelling of his surname from Schönberg to Schoenberg. Schönberg's approach, both in terms of harmony and development, has been one of the most influential of 20th-century musical thought.