Devanagari Pa प

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.

With the fifth class the twenty-five stops are complete, and it is worth reading the arrangement as a single object rather than as five rows learned one after another. Sanskrit closes the vocal tract at five points. At each point, two independent features, whether the vocal folds vibrate during the closure and whether breath is released after it, generate four stops. At each point there is exactly one possible nasal, made by lowering the soft palate so the air escapes through the nose, and that nasal closes the class. Five places times five members gives twenty-five, with nothing left over and no letter that fails to fit.

What follows in the table is described by different criteria: four semivowels that correspond to four of the vowels, and three sibilants with the breath h, grouped as the sounds made with continuous air rather than a closure. The whole of it is an analysis of the sound system of one language, presented in the order that the analysis implies. That is what makes the varnamala a different kind of object from the Greek, Hebrew and Roman alphabets covered elsewhere in this atlas, whose order preserves an inherited Phoenician sequence and carries no phonetic information at all. It is also why a Sanskrit dictionary is alphabetised by articulation and why a grammatical rule can name a class of sounds in two syllables.