three last syllables was completed by these changes which did away with all the cases in which it had stood on the fourth syllable from the end.
Brevis Brevians
§ 95. Next must be mentioned another phonetic change, also dependent upon Accent, which had come about before the time of Plautus, the law long known as the Brevis Brevians which may be stated as follows: A syllable long by nature or position, and preceded by a short syllable, was itself shortened if the accent of the word fell immediately before or immediately after it,—that is, on the preceding short syllable or on the next following syllable. The set of syllables need not be in the same word, but must be as closely connected in utterance as if they were. Thus mŏ́dō became módŏ, ŏ́dōr became ŏ́dŏr, vŏluptā́tem became vŏlŭ’tā́tem, est in quĭ́d est? became a short syllable (either the s or the t or both being only faintly pronounced).
§ 96. It is clear that a great number of Inflexional syllables which had been shortened by this Phonetic Change, must have had their quantity immediately restored on the pattern of the same inflexion when it occurred in words not of this particular shape; thus, for instance, the long vowel of ắmā is due to that in other verbs (pulsā, agitā) not of iambic shape. So Ablatives like modō, sonō got back their -ō as we have seen (§ 15), though in Adverbs like modo ‘only,’ quōmodo ‘how’ the shortened form remained. Conversely the shortening of the final -a in the Nom. Sing. Fem. of the a-declension (contrast lūna with Gr, χώρᾱ)
