The true analogy lies in the simple fact that the ear is susceptible to certain sounds produced by air-waves of certain frequencies, while the eye is susceptible to certain colors produced by ether-waves of certain frequencies, and it is possible to mechanically combine in one case the sounds so as to produce harmonies that please the ear, and in the other case the colors so as to produce harmonies that please the eye; and so far as pure sound and pure color is concerned, the harmonious compositions need have no relation, imitative or otherwise, to anything in nature. * * * * * The uneducated ear prefers melodies which are more or less suggestive of sounds heard in nature,--more or less realistic imitations of songs of birds, rippling of waters, falling of rain, rustling of leaves, crashing of thunder, etc.; or if familiar sounds are not imitated, the title of the composition must suggest some incident, place, or scene more or less familiar, so the deficient ear may be helped out by the imagination. The highly-trained ear, on the other hand, delights in abstract compositions of sound, in harmonies which have no perceptible relation to any sound in nature, and which do not suggest any person, scene, or incident in literature or history. The purer the taste in music the more abstract the compositions that satisfy. So far as the appreciation of color harmonies is concerned, the taste of the Western world is like unto that of the uneducated ear in music. We are not content with pure color compositions as we are with pure sound, but we demand either imitations of natural objects or representations of historical, literary, religious, or emotional subjects. We must have something besides pure line and color. A musician may strike a succession of notes, or a chord, and we are pleased, the ear is satisfied; but if the painter simply sweeps his brush several times across the canvas, we are not satisfied, though the combination of colors be something more beautiful and harmonious than anything ever seen. It is not a “picture” to us; it lacks the “subject” to which we are accustomed. And yet there are in existence certain canvases by Whistler which are little more than color-schemes, and which in color-effects are among the most beautiful things he ever painted; and in all the galleries of Europe there is nothing to compare with them in pure joyousness of color.