No one who has not seen him at work can form any adequate notion of his extreme susceptibility to infinitesimal variations of color; it exceeded that of any painter of whom the Western world has sufficient record for comparison. A Frenchman has said: “Whistler’s works are dreams of color. The gray of them is unique. It is made of white, blue, green, of all the tints. It is the tender gray of England’s coasts, of the North Sea, and of the sky that in summer is above it; the horizon gray where the pale blue of the sky and the pale green of the sea unite and form one. “It is a subtle shade, in accord with the penumbras in which he delighted. He was the musician of the rainbow. No one understood as well as he the mysterious relations of painting and of music, the seven notes and the seven colors, and the way to play these with the sharps and flats of the prism. Even as a symphony is in D or a sonata is in A, his pictures were orchestrated according to a tone,--the ‘Lady with the Iris,’ for example, a mauve flower placed in the hand of the figure, as a note and signifying that the portrait was to be a colored polyphony of lilac and of violets. “More precision is lent to this curious æsthetic by the titles that he gave to certain small canvases representing twilights of Venice and of London, which he entitled ‘Nocturnes,’ in a parallel with those of Chopin, but of a Chopin serene and who dreams instead of a Chopin ill and who weeps. There, as in portraits, the gray of England’s coasts appears, but bluer. It has in portraits the tints of twilight in ashes. In all his works he reveals the land of his origin, the land that has produced Edgar Allan Poe.” Many stories are told illustrating his susceptibility to color. Some of them are pointless; but the fact they are told at all shows how this trait impressed both the artists and the public. “One morning he had an engagement at a banker’s, where he was to receive a large sum of money for a set of etchings, a sum that he happened to need very much at that time. He was busy chatting and showing some of his things to an appreciative visitor, who happened to know the circumstances, and considerately reminded him that he had far to go and that the American would probably be in a hurry and would not wait. “‘Yes,’ said Whistler; ‘but just look at this now,’ pulling forward another canvas. And so it went on, until his friend said: ‘Whistler, you really must go! That man will never wait for you.’ “‘What a nuisance you are!’ he exclaimed; but he got ready, and they started.