Claude Debussy
Prelude to the Afternoon of a Faun (1892)

A tone poem in one movement
2018 is the centenary of the death of Claude Debussy (1848–1918), who is said to have been the first truly twentieth century composer. It is with this work that most commentators say that musical impressionism began, for in its evocation of the Stéphane Mallarme poem, Debussy avoids the conventional syntax of music of the nineteenth century in favor of a continuous flow of musical ideas linked only by their ability to evoke the mood of the poem. Like the poem, there are no regular periods of musical ideas, no clear divisions of the music into sections, no cadences where the music rests before beginning again. The harmonies are chosen for their color alone; the melodies, although beautiful, seem to emerge out of the mist of the music and fade away. It is, quite deliberately, the musical  equivalent of a Monet landscape.
Debussy came to this musical revolution slowly; his early works from 1880-1890 are very much in the style of the more conservative French composers of his time. But he always had a rebellious streak and felt that the rules of harmony were hamstringing his creatively. He loved to shock his fellow students by playing beautiful disconnected chord that violated all the rules and to exclaim “see how beautiful they are?” These chords infiltrated his music, but their big coming out party was this 1892 score, which shocked the musical establishment. However, its beauty and lyricism was a hit with the public, and the “Afternoon of a Faun” quickly became an orchestral repertoire staple.
“It is here that the twentieth century begins” said the conductor and composer Pierre Boulez, whose debt to Debussy can be heard in everything he ever wrote. Ironically, Debussy died just before the end of the Great War, which most commentators feel was the end of the culture and order represented by the 19th century.