Tom Service considers whether Claude Debussy was an impressionist or not. He is often said to have composed Impressionist music - in such popular works as Claire de Lune and La Mer. But Tom argues that Debussy's music has quite a different character to that of the Impressionist painters - and to prove it he discusses the techniques of those painters with art historian Anthea Callen. Debussy, Tom argues, was a modernist, an abstract composer and also (in his opera Pelléas et Melisande) a creator of nightmares.