Kalpa is one of the six disciplines of Vedanga, treating ritual. Tradition does not single out any special work in this branch of the Vedanga; but sacrificial practice gave rise to a large number of systematic sutras for the several classes of priests. A number of these works have come down to us, and they occupy by far the most prominent place among the literary productions of the sutra-period. The Kalpa-sutras, or rules of ceremonial, are of two kinds: (1) the Shrautasutras, which are based on the shruti, and teach the performance of the great sacrifices, requiring three or five sacrificial fires; and (2) the Smartasutras, or rules based on the smrti or tradition. The latter class again includes two kinds of treatises: (1) the Grhyasutras, or domestic rules, treating the rites of passage