This passage illustrates the partiality of fugue writers for treating the third of the tonic as the sixth of the dominant, and the leading note as the third of the dominant. There is no necessity for a tonal change till (a), and the answer might have been
Here we have another example of what we haye already seen more than once, that it is sometimes possible for a subject to have two different answers, both correct. The student will learn by experience, in such cases, which is the better.
144. Though, as a general rule, the transposition of the subject a perfect fourth or fifth should be strictly carried out, we often find the position of the semitones disregarded, a semitone being answered by a tone, and a tone by a semitone. This is especially the case with the subdominant and leading note, as will be seen by the following passages, selected from a much larger number we had marked for quotation—
J. S. Bach. Fughetta on "Allein Gott in der Höh' sei Ehr'."
J. S. Bach. Mass in B minor.
Mozart. Litany in B flat.
