Whistler explained his artistic philosophy and his reason for including musical terms in his works’ titles in his famous “Ten O’Clock Lecture,” a part of which was published in his book The Gentle Art of Making Enemies :
“Why should not I call my works ‘symphonies,’ ‘arrangements,’ ‘harmonies,’ and ‘nocturnes’? I know that many good people think my nomenclature funny and myself ‘eccentric’… The vast majority of English folk cannot and will not consider a picture as a picture, apart from any story which it may be supposed to tell…
As music is the poetry of sound, so is painting the poetry of sight, and the subject-matter has nothing to do with harmony of sound or of colour [sic]… Art should be independent of all clap-trap – should stand alone, and appeal to the artistic sense of eye or ear, without confounding this with emotions entirely foreign to it, as devotion, pity, love, patriotism, and the like. All these have no kind of concern with it and that is why I insist on calling my works ‘arrangements’ and ‘harmories…”
James McNeill Whistler, “The Red Rag,” in The Gentle Art of Making Enemies (London: William Heinemann, 1890), pp. 126-7.