摘要
In Classical Tibetan, y can occur in initial position (called ya) as well as in medial position (called ya btags). Initial y can be preceded by the prefix g, while y can follow initial g. Consequently there is a contrast between g-y and gy. From the difference in the way they are spelled in Tibetan writing system and from their divergent developments in modern Tibetan dialects, it can be inferred that there was an original phonetic distinction between them. As for the true nature of the difference, scholars differ in their interpretations.
Based on the evidence of some morphological peculiarities involving initial y in classical Tibetan, the author claims that initial y was originally preceded by a glottal stop, which was lost in the course of time when not preceded by any prefix. When, however, causative was formed through prefixing s to initial y preceded bya glottal stop, the morphophonemic rule requires the glottal stop be replaced by k. When the present tense was formed through prefixing a-chung('), kh occurs instead of k. The morphophonemic alternation of k and kh with "zero" is interpreted as the evidence of the lost glottal stop between the prefix g and the initial y, i.e. g-?y rather than simply g-y. As far as the medial y is concerned, there is some restriction on its distribution. It can only occur after velars and labials and can never occur after dentals and palatals. The morphophonemic alternation of dentals with palatals shows the development of dentals into palatals caused by infixation of medial y.
The function of medial y has been largely ignored in the literature. The author gives twenty pairs of examples to show that one of the functions of medial y is to form honorifics.