III. A FUGUE BY BACH.
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."
As is suggested by the derivation of the word "fugue," from the Latin "fuga," a flight, the characteristic peculiarity of the form is the entrance, one after another, of the several voices, which thus seem to pursue or chase one another, to go through a sort of musical game of "tag," in which first one and then another is "It." First one voice begins with the "subject" of the fugue, in the "tonic" key (key in which the piece is written). Next enters a second voice, "imitating" the first, but presenting the subject not in the "tonic," but in the "dominant" key. Then a third, once more in the tonic, and finally the fourth, again in the dominant. After these entrances all four voices proceed to play with the subject, transposing it in all sorts of ingenious ways, and straying off at times into episodes, generally in "sequence" form, but finally coming back, towards the end of the fugue, with renewed energy to the subject itself. All this may be seen in such an example as the Fugue in C-minor in Bach's "Well-Tempered Clavichord."