Page:Fugue by Ebenezer Prout.djvu/100

82 writers, though occasional exceptions, with which we need not now concern ourselves, are to be met with.

182. Our next question is, By which voice of the other pair (supposing the fugue to be for four voices) should the answer be given? If, for instance, the treble leads with the subject, should the alto or the bass have the answer? It is seldom difficult to decide this point, if we remember that it is generally best for the last entry in the exposition to be in an outer, rather than in a middle voice. The reason for this is that it is easier to distinguish the subject or answer when it is in an outer part, especially in fugues with four or five voices. In three-part fugues, owing to the thinner harmony, an entry in a middle part can be more clearly heard. In the forty-eight fugues of Bach's 'Wohltemperirtes Clavier,' the last entry is in an outer part in no fewer than forty-two—seven out of every eight.

183. In a two-part fugue, the exposition will be a very simple matter. One of the voices (it is indifferent which) leads with the subject; the other follows with the answer, which the leading voice accompanies with the counterpoint or countersubject, as the case may be, and the exposition is complete.

184. In a three-part fugue, the operation is somewhat longer. If one of the outer parts has the subject, the middle part usually has the answer, and the remaining outer part has the subject again. If the middle part commences, the answer may be equally well in either of the outer parts—it is quite immaterial which. Occasionally we find one outer part leading, and the other outer part following, the middle voice being the last to enter. This, however, is rare; out of twenty-six three-part fugues in the 'Wohltemperirtes Clavier' there are only two (Nos. 27 and 28) in which this method is adopted.

185. While the second entering voice gives the answer, the first continues with the countersubject, supposing there to be one; on the entry of the third voice with the subject, the second voice, which has just concluded the answer, continues with the countersubject, as the first voice did before. The countersubject, which previously accompanied the answer, must now be transposed a fourth or a fifth to serve as a counterpoint to the subject. It may also, in the case of a tonal fugue require some modification (§ 170). Meanwhile, the leading voice, having now completed the countersubject, adds a fresh counterpoint, which may also be a second countersubject; in this case the subject and the two countersubjects must be written in triple counterpoint. If the third part be a free part (as as mostly the case), triple counterpoint is not necessary.

186. Here the exposition of a three-part fugue may end; but, for a reason now to be shown, it is often continued a little further. It was said in the last chapter (§ 160) that a countersubject should be written in double counterpoint to the subject, so as to be able to be used both above and below it. But