Impressionism, technically.
Emma Bardac was Claude Debussy's wife.
Actually, Claude is his middle name. His full name was Achille-Claude Debussy.
Emma Debussy died of diptheria. Diptheria is a bacterial, infectious disease that affects the throat and nose. It can be life threatening, and in Emma's case, it ended her life.
This piece is based on an ancient Breton myth in which a cathedral, which is submerged underwater off the coast of the Island of Ys, rises up from the sea on clear mornings when the water is transparent. Sounds can be heard of priests chanting, bells chiming, and the organ playing, from across the sea.
Many opinions, so here's mine: Claude-Achille Debussy was experimenting with a new tonality, the whole-note scale, where every step is a whole note (the major scale runs whole, whole, half, whole, whole, whole, half). It's a marvellous effect. Pieces that come quickly to mind are: Prelude to the Afternoon of a Faun Claire de Lune (Moonlight) the Girl with the Flaxen Hair la Mer (the Sea) a string quartet Two close contemporaries exploring similar kinds of sound were Maurice Ravel and Gabriel Fauré.