James McNeill Whistler (1834-1903), the American-born painter and etcher, became a crucial link between the Paris and London art worlds of the mid-nineteenth century. Influenced first by Courbet's realism, he evolved his own distinctive aesthetic, stressing 'an arrangement of line, form and colour first'. His Nocturnes are among the most highly-regarded of his works.

He wrote more than 5,000 letters which, with his published writing and conversations, illuminate his work and his contentious relations with the art world of the time. Whistler on Art includes seventy-five items: letters (many not published before) and material recording his disillusionment with English approaches to art and his response to the French, Scottish and American art worlds.

Whistler was a friend of the Pre-Raphaelites and enjoyed a fruitful dialogue with Swinburne and with Wilde (whom he later accused of plagiarism) and emerged at the centre of the Aesthetic Movement. Against Ruskin (who attacked him) he won a libel suit and a farthing's damages. The trial sharpened Whistler's polemical gifts, and he wrote stinging pamphlets and letters to the press. In his 'Ten O'Clock Lecture' he attacked Ruskin's view of the moral purpose of art. A friend of Mallarmé and other French writers and painters, he is (with Monet) one of the models Proust drew on for the character of the painter Elstir.