combines it with the first part of the subject of the fugue in the following manner—
It looks at first sight as if there were here a double fugue (§ 175), with an independent exposition of its second subject. That this is not really so, is shown by the fact that the episodical theme does not subsequently appear regularly as a counterpoint to the subject.
229. Sometimes in the same fugue some of the episodes will be made from material already used, while others will be constructed of entirely new matter. An excellent example of this will be met with in the 37th fugue of the 'Wohltemperirtes Clavier.' We have already quoted the subject and countersubject of this fugue at § 162 (b). There are altogether four episodes. Of these the first and third were quoted in § 256 of Double Counterpoint, as an example of triple counterpoint in all its possible positions. The second episode is made from a sequential treatment of the countersubject, and the fourth is a transposition of the second, with inversion of the upper parts. This is often met with: for instance, in the two-part fugue in E minor (No. 10 of the 'Wohltemperirtes Clavier') there are four episodes, of which the third is an inversion of the first, and the fourth of the second.
230. We could multiply examples to any extent, and have, in fact, noted far more for quotation than we have room to insert; but we have already given enough to allow us to deduce general principles from them as to the construction of episodes. The first, and one of the most important inferences to be drawn from our illustrations, is the essential part played by sequence in nearly all the episodes. If we were forced to restrict ourselves to giving the student only one rule in this matter, we should select, as the most valuable we could give him, "Construct your episodes sequentially." Sequences not only furnish a very easy and simple means of modulation, but they combine variety of detail with unity of design in a degree which perhaps no other artistic device can attain. It is not necessary that the sequential
