ninth contain the Dharma Sutra, and the thirtieth section, the Sulva Sutra, teaches the geometrical principles according to which the altars for the sacrifices had to be constructed. In addition to the Sutras, ancient writers enumerate five other Vedangas, or departments of Vedic study, which may be briefly enumerated here.
Siksha, or Phonetics, is the science of pronunciation, and there is reason to believe that rules on the subject were formerly embodied in the Aranyakas and even in the Brahmanas, but that they have disappeared in consequence of the appearance of more scientific works on the same subject in the Philosophic Period. These works are called Pratisakhyas, since they were collections of phonetic rules applicable to each Sakha, or recension, of each Veda.
Many of the Pratisakhyas, however, have been lost, and only one Pratisakhya for each Veda (except the Sama-Veda) has been preserved to us. The Pratisakhya of the Rig-Veda is ascribed to the renowned Saunaka. Similarly, a Pratisakhya of the White Yajur-Veda is also extant and is ascribed to Katyayana. A Pratisakhya of the Black Yajur-Veda and one of the Atharva-Veda are also extant, but the names of the authors are forgotten.
Chhandas, or Metre, is mentioned in the Vedas, and whole chapters in the Aranyakas and Upanishads are devoted to it. But as in the case of Siksha, so in the case of Chhandas, we have a clear scientific treatment of the subject for the first time in the Sutra literature.
