The conclusion is emphasized by the finely rugged statement of the subject in Bass at measure 26.
The treatment of this fugue, for all its consummate skill, is comparatively simple. It does not employ the more subtle devices often employed in fugues, of which may be mentioned the following:
1. "Inversion:" The subject turned upside down, while retaining its identity by means of its rhythm.
FIGURE XIII. THE DEVICES OF "AUGMENTATION" AND "DIMINUTION."
2. "Augmentation and Diminution:" The length of the notes doubled or halved, while their _relative_ length, or rhythm, is carefully maintained. (Figure XIII.)
3. "Shifted rhythm:"[8] The subject shifted as regards its position in the measure, so that all the accents fall differently.
4. "Stretto:" The imitation of the subject by a second voice occurring prematurely, before the first voice has completed the subject, frequently with highly dramatic effect. (_b_) in Figure IX is an example of stretto.
These devices are mentioned here not only because they occur in many fugues, but because they are used in the symphonic music of Mozart and Beethoven, as we shall later have occasion to see.
Perhaps the most exacting of all tests applicable to music is the test of economy. Are there superfluous tones that do not enrich the harmony? Are there unnecessary subjects not needed to fill the scheme of design? If so, no matter how beautiful the music, it is defective as art. Bach bears this test victoriously. There is not a note of his writing which one would willingly sacrifice. There is not a melody that is not needed. Each subject is not merely introduced and dismissed, but is developed to the utmost, so that all that was implicit in its germ becomes explicit in its final form. There is no confusion of the outline, no overcrowding of the canvas, no blotchiness in the color. As Giotto proved his supremacy among draughtsmen by the apparently simple but really enormously difficult feat of drawing a complete, perfect circle with one stroke of the pencil, so Bach constantly proves his supremacy among musicians by making two voices satisfy the ear like an orchestra. And this purity of texture is quite compatible with the utmost richness. Indeed, Bach's polyphonic scores are inimitably rich, since each voice sings its own melody, and the melodies all interplay harmoniously like the lines of a well-composed picture. Those who call Bach's fugues dry make an astonishing confession of their own insensibility or crudity of taste. Bach's melodies are not, to be sure, like "Annie Laurie" or "Home, Sweet Home." But neither is daylight like candle light; yet we do not call it darkness because it is diffused through all the atmosphere instead of concentrated in a single visible ray.