and the last four furnish the beginnings or (in one case) the full development of five branches of science that flourished in the post-Vedic period. In the fourth and sixth group the name of the class has been applied to designate a particular work representing it.
Of kalpa we have already treated at length above. No work representing astronomy has survived from the Vedic period; for the Vedic calendar, called jyotisha, the two recensions of which profess to belong to the Rigveda and Yajurveda respectively, dates from far on in the post-Vedic age.
The Taittirīya Āraṇyaka (vii. 1) already mentions çikshā or phonetics, a subject which even then appears to have dealt with letters, accents, quantity, pronunciation, and euphonic rules. Several works bearing the title of çikshā have been preserved, but they are only late supplements of Vedic literature. They are short manuals containing directions for Vedic recitation and correct pronunciation. The earliest surviving results of phonetic studies are of course the Saṃhitā texts of the various Vedas, which were edited in accordance with euphonic rules. A further advance was made by the constitution of the pada-pāṭha, or word-text of the Vedas, which, by resolving the euphonic combinations and giving each word (even the parts of compounds) separately, in its original form unmodified by phonetic rules, furnished a basis for all subsequent studies. Yāska, Pāṇini, and other grammarians do not always accept the analyses of the Padapāṭhas when they think they understand a Vedic form better. Patanjali even directly contests their authoritativeness. The treatises really representative of Vedic phonetics are the Prātiçākhyas, which are directly connected with the Saṃhitā and
