Page:Fugue by Ebenezer Prout.djvu/223

Chap. XI.] subjects. But the length to which the composition will extend will necessarily be so great that this kind of triple fugue is extremely rare. We have met with no other example of it than that which we have been analyzing, though Albrechtsberger mentions a similarly constructed fugue in G minor by Mattheson, from which he quotes a few short passages.

404. In the ordinary triple fugue, the three subjects are announced simultaneously, like the two subjects in the double fugues seen in §§ 370 to 377. But in a four-part fugue, it is evident that the method of exposition in the examples of §§ 370 to 374 will be impossible. After three of the voices have announced the three subjects (which, it must be remembered, should not begin exactly together, though they must all finish together), the fourth voice should enter with the answer to the first subject, two of the other voices giving the other two answers, while the remaining voice may either be silent or add a free part. The three subjects are then heard again, differently distributed between the voices, and then the three answers once more. The exposition is complete as soon as all the subjects have been heard (either as subject or answer) in each of the voices. It is important to remember that the same subject should not be heard twice in succession in the same voice.

405. The instructions given in the last paragraph will be now illustrated by the exposition of a triple fugue by Albrechtsberger.