Page:Fugue by Ebenezer Prout.djvu/81

Chap. IV.] 147. Sometimes, though very seldom, we find a final modulation to the dominant answered by one to the supertonic, as in the example (f) of § 107, where, however, Mendelssohn harmonizes the last notes of the answer in F minor, instead of F major, so as not to leave the circle of nearly related keys. In the following passage there is a distinct modulation to A major in the answer—

148. Our last illustration of this point is instructive.

Notice, in passing, the minor third at the end of the subject answered by a major third (§ 69). We see here the only example in all Bach's works of a real answer given to a subject that closes in the key of the dominant; but here it can be not only explained but justified. We have already spoken (§ 139) of the importance of retaining augmented and diminished intervals as far as possible in the answer. Had Bach given a tonal answer here,

he would have had to sacrifice the diminished fifth in the second bar, and the harmonic framework of the bar would have been entirely changed. But there is a further reason here. We said, in § 116, that a tonal answer was required when the subject modulated to the dominant, in order to get back to the tonic for the entry of the third voice. But the fugue we are now discussing is for two parts only; and after the first entry of the answer, the exposition (§ 11) is complete, and we reach the first episode, where, as we shall see later, modulation usually begins. There is, therefore, here no occasion to return to the tonic key. The same reason may probably explain the putting the second answer into the key of the subdominant, noticed in § 111. Students should always keep to the regular rule, and answer a subject modulating to the dominant by a return to the tonic.