[Music: score] FIGURE X. "Sequence" from Bach's Invention in F-Major.
The difference in texture between this piece and any folk-song or dance will best be appreciated by playing over the bass part alone, when it will be seen that, far from being mere "filling" or accompaniment, it is a delightful melody in itself, almost as interesting as its more prominent companion. Indeed, in the whole invention there are only two tones (the C and the A in the final chord) which are not melodically necessary. Such is the splendid economy and clearness of Bach's musical thinking.
Before going further, the reader should examine for himself several typical inventions, as, for example, No. I, in C-major; No. II, in C-minor; No. X, in G-major, and No. XIII, in A-minor, in this set by Bach, noting in each case: (1) the individuality of the motives used, (2) the imitations from voice to voice, (3) the sequences, (4) the modulations, (5) the polyphonic character, as evidenced by the self-sufficiency and melodic interest of the bass, and (6) the structural division of the entire invention into more or less distinct sections.
The same general method of composing that is exemplified in the inventions we see applied on a larger scale in the fugues of Bach.
The definition of a fugue given by some wag--"a piece of music in which one voice after another comes in, and one listener after another goes out"--is true only when the listeners are uneducated. For a trained ear there is no keener pleasure than following the windings of a well written fugue. It is, at the same time, true that a fugue presents especial difficulties to the ear, because of its intricately interwoven melodies. In a folk-song there is not only but one melody, with nothing to distract the attention from it, but it is composed in definite phrases of equal length, like the lines in poetry, with a pause at the end of each, in which the mind of the listener can take breath, so to speak, and rest a moment before renewing attention. Not so in the fugue, where the bits of tune occur all through the whole range of the music, are of varying lengths and character, and overlap in such a way that there are few if any moments of complete rest for the attention. Perhaps this is the chief reason why fugues have the reputation of being "dry."