Pa: The Last of the Five Classes

Pa is the twenty-first consonant of the varnamala and the head of the fifth and last varga, the labial class, made by closing the lips. With it the progression that organises the whole consonant table reaches the front of the mouth, having begun at the soft palate with ka and moved forward through the hard palate, the crown behind the teeth ridge, and the teeth themselves.

The Sanskrit phoneticians named the class oshthya, from the word for lip, and set the labial vowels u and long u in the same articulatory family, so that the correspondence between vowels and consonants made at the same point holds here as it does for the velars and the palatals. That correspondence is not decorative. It is used in the rules, most visibly in the rule that turns u into the labial semivowel va when a dissimilar vowel follows, which is the exact counterpart of the rule turning i into ya. The letter opens a large body of central vocabulary in Sanskrit and in the modern languages, and its written form descends through the Nagari and Siddhamatrika hands from a Brahmi original of the same value, a descent traced through the inscriptional record in Richard Salomon's guide to Indian epigraphy. Sanskrit uses the letter as the first element of the name of its own class, since every varga is named after its first member, so the labial class is referred to by a compound formed on this letter. The convention holds for all five classes and is part of what allows a grammatical rule to identify a group of five sounds in a single word.