14 Phonology [§ 3» the accent was predominantly stress. This difference in the system of accentuation is clearly seen in Old Greek and the old Germanic languages by the preservation of the vowels of unaccented syllables in the former and the weakening or loss of them in the latter. In the early period of the parent Indg. language, the stress accent must have been more predominant than the pitch accent, because it is only upon this assumption that we are able to account for the origin of the vowels ī, fi, a (§ 35, Note i), the liquid and nasal sonants (§§ 58-β), and the loss of vowel often accompanied by a loss of syllable, as in Greek gen. πα-τρ-os beside ace. πα-τέρ-α ; πέτ-ofiai beside έ-πτ-όμην ; Gothic gen. pi. auhs-nē beside ace. *aúhsa-ns. It is now a generally accepted theory that at a later period of the parent language the system of accentuation became predominantly pitch, which was preserved in Sanskrit and Old Greek, but which must have become predominantly stress again in prim. Germanic some time prior to the operation of Verner's law (§ 136). The quality of the accent in the parent language was partly 'broken' (acute) and partly 'slurred' (circumflex). This distinction in the quality of the accent was preserved in prim. Germanic in final syllables containing a long vowel, as is seen by the difference in the development of the final long vowels in historic times according as they originally had the'broken' or 'slurred'accent (§§87 (i), 89). In the parent language the chief accent of a word did not always fall upon the same syllable of a word, but was free or movable as in Sanskrit and Greek, cp. e. g. Gr. nom. πατήρ, father, voc. πάτερ, ace. ποτέρα; Skr. emi, I go, pi. imás, we go This free accent was still preserved in prim. Germanic at the time when Verner's law operated, whereby the voiceless spirants became voiced when the vowel immediately preceding them did not bear the chief accent of the word (§ 136). At a later period of the prim.