A secondary and subordinate advantage of music proceeds from the nature of its material. Tones, produced and controlled by man, are far more easily stamped with the unity he desires than the objects of external nature. These are stubborn outer facts, created without regard to the æsthetic sense, and in a thousand ways unamenable to it. The great dazzle of sunlight is too keen for human eyes, which perceive better on dim, gray days; many of nature's contours are larger than we can grasp. Every painter will tell you that there are inharmonious colors in the sunset, and one daring critic has gone so far as to impugn the «vulgarity of outline» of the American hills. It matters not whether the maladjustment indicate a fault in nature or a limitation in man; the point to note is that the representative arts deal with a material less pliable than tones. Words, the material of poetry, occupy in this respect a curious intermediate position. Like tones, they are man-made, but, like outer objects, they are «given,» fixed and indocile to man's æsthetic needs. (We remember the example of the «hatter.») Though made by man, in fact, they are made not by his æsthetic but by his practical energy. They were devised, not for beautiful adjustment, but to convey thoughts, and when the poet comes and uses them to make an art he finds them almost as perverse as the painter's trees and hills. Tones, however, have no practical utility whatever; not only do they not exist outside of music, but they would be of no use if they did. Hence they may be chosen and grouped by the free æsthetic sense alone, acting without let or hindrance, except what is imposed by the thing to be expressed. For hundreds of years man has been testing and comparing, accepting and rejecting, the elements of the tonal series, with the result that we have to-day the ladder or scale of ninety-odd definitely fixed tones, out of which all music is composed. And though the series has been developed wholly by instinct, and it is only within the last half-century that the natural laws underlying it have been discovered, yet it has been built up so slowly and tentatively, and with so sure and delicate a sense of its internal structure, that it is an unsurpassable basis for complex and yet perfectly harmonious tone-combinations. In a word, the material of music is by origin self-congruous, fitted to clear structure, preordained to an order at once rich and transparent.