that part of the countersubject which is written against the latter part of the subject can seldom be also made to fit the first part which, in a stretto, will be appearing in another voice; while, if all the voices are joining in the stretto, there will evidently be none left to give the countersubject. As the second subject in a double fugue is virtually a countersubject to the first, it is clear that the same reasoning will apply to it. Consequently the stretti, when there are any, in a double fugue are mostly made from one subject alone, and very often take the place of the episodes.
382. The general rules as to the order of entries, etc., given in § 325, apply also to double fugues, excepting that in the latter there should be no isolated entry for one of the subjects unaccompanied by the other. One entry of the two subjects together may, however, be divided by episodes from the preceding and following.
383. Our space will not allow us to give complete examples here of double fugues, as we did of simple fugues in Chapter IX. In the volume on Fugal Analysis, which will follow the present one, we shall insert some fine specimens of this kind. Meanwhile it is hoped that the explanations given in this chapter will enable the student to understand the construction of a double fugue, and, if necessary, to write one for himself.
384. We have now to speak of the second variety of double fugue—that in which each of the two subjects has its own separate exposition, and it is only in the latter part of the fugue that they appear together. Though some very fine examples of such fugues are to be found, they are far rarer than the kind of which we have been hitherto speaking, and they are constructed after a different plan.
385. It is, of course, just as necessary in this kind of fugue as in the other that the two subjects must be composed together in the first instance, and that they must be in double counterpoint with one another; otherwise it is in the highest degree improbable that it will be possible to combine them. The essential difference between this and the other class of double fugues is, that here the combination, instead of being shown at first, is reserved for the climax, whereby its effect is frequently much increased.
386. There is considerable difference in various fugues of this class as to the amount of separate treatment which each subject receives before they are brought together. Sometimes the first subject will have a regular exposition, and the second only a partial one, as in the following passage, which, to save space, we give in short score.
