Willem Pijper (1894–1947) is generally considered one of the most important figures in modern Dutch music. Between 1918 and 1922 he grew into one of the more advanced composers in Europe. In each successive work he went a step further and, from 1919, Pijper's music can be described as atonal. However, Pijper remained a composer of strong emotional character, to which his Third Symphony (1926) bears witness. In Pijper's later works the harmonic expression seems at times to approach monotonality. As a teacher Pijper had a great influence on modern Dutch music, teaching many prominent Dutch composers of the 1950s, 60s, and 70s. He was senior master of instrumentation in the Amsterdam Conservatoire, and from 1930 until his death in 1947 he was Head of the Rotterdam Conservatoire.