175. Some theorists speak of a fugue with a regular countersubject as "a fugue with two subjects," or "a double fugue." It is best, however, not to apply this name to fugues such as those we have been speaking of, unless the countersubject, as is sometimes the case, does not appear in the first exposition, but has later an independent exposition of its own, and is not at first used as an accompaniment to the subject, with which it is not combined till its own separate exposition is completed. We shall treat of fugues of this kind, as well as of the other variety of double fugue, in which the second subject first appears not against the answer (as in the examples here given), but against the first subject, later in this volume (Chapter XI.).
176. It is by no means necessary that every fugue should have a regular countersubject. Of the forty-eight fugues in the 'Wohltemperirtes Clavier' there are seventeen which have none; and the question naturally arises, When it is desirable to write a countersubject to a fugue, and when can it be suitably dispensed with? It is impossible to lay down a hard and fast rule on the matter; but a careful examination of those fugues which have no countersubject shows that, in a large majority of cases, it is unnecessary, if the subject is intended to be elaborately combined with itself. The exact meaning of this will be better understood when we come to speak of the middle section of a fugue, and of stretto; but one or two illustrations will help to make the matter clearer. In fugues Nos. 1, 22, 26, 29, and 31, we find no countersubject, because the subject itself is so largely treated in stretto (§ 16) that a countersubject would only have been in the way. In fugues 8 and 20, the subject is treated by inversion and in canon, and in No. 27 extensive use is made of inversion and diminution. On the whole it may be said that, when there is no countersubject, we mostly find the more scientific devices of fugue writing applied to the subject itself. This, however, must not be taken for more than an attempt at generalization. There is no form of composition in which there is so much liberty of treatment and variety of detail as that of fugue.
177. The student should now compose countersubjects to all the fugue subjects given at the end of Chapter IV. He should try to write at least two or three, differing in character, to each subject. For this purpose he should write the subject on one staff, following it on a second by the answer, above or below which, according to its position, he should write his countersubject as the continuation of the subject. He may always introduce a short codetta, if necessary, between the end of the subject and the beginning of the countersubject, but it is best not to leave a rest between the two. The first voice should go on continuously to the end of the countersubject.[1]
- ↑ We occasionally find exceptions to this sound general principle, e.g., in Nos. 16 and 30 of the 'Forty-Eight' in both of which the entry of the countersubject is preceded by a rest, probably to call attention to it more strongly. We shall see later that a rest is generally advisable before the re-entry of the subject.
