for the guidance of the student. We said in § 248 that a stretto might be at any interval; to this we now add that it may be in any number of parts. If a stretto is employed in a fugue at all, we generally find more than one; and in that case, in order that the interest of the music may gradually increase, we mostly find the later stretti either in more parts or at a shorter distance of entry, or both, than the earlier ones.
252. It is not always possible for the voices which enter first in a stretto to continue the subject after another voice has entered. This was shown in § 247 at (d), where the bass had to discontinue the subject on the entry of the treble. Though it is best to carry on the imitation as far as possible, it is always allowed to break off the subject, or to modify it after another voice has taken it up. But it should be remembered that the last entering voice in a stretto should have the subject complete. We of course use the words "subject" and "answer" indifferently here, as the entry may be at any interval.
253. From the same consideration—that of freedom of interval in the entries—we are allowed in a stretto of a tonal fugue to employ either subject or answer, as may be more convenient. The imitations in a stretto may also be by augmentation, diminution, or inversion, or (as we saw at (d) § 247) per arsin et thesin.
254. We will now write a subject and answer adapted for stretto, and then show some of the numerous stretti of which it is capable.
As there is here in the subject an implied modulation to the dominant, the answer will be tonal. In accordance with the rule given in § 121, we regard the modulation as being made as early as possible—here, after the first note of the subject. The answer enters at the beginning of the fifth bar.
255. We will first try to bring in the answer as near the end of the subject as we can. Clearly if we keep the tonal answer, we cannot introduce it in the fourth bar of the subject.
This is manifestly impossible, though the addition of thirds below the answer would render it practicable. But we said in § 253 that it was allowed to use either form of the subject
