Kalpa-sutra, manual of Hindu religious practice, a number of which emerged within the different schools of the Veda, the earliest sacred literature of India. Each manual explains the procedures (kalpa) of its school as it applies to three different categories: the sacrificial ritual (Shrauta-sutras), the domestic ritual (Grihya-sutras), and the conduct of life (Dharma-sūtras; see Dharma-shastra). They are written in the short aphoristic style of the sutra (literally “thread”) so that they could be committed easily to memory. Kalpa is one of six fields of scholarly discipline known as Vedangas (“accessories to the Vedas”). As they are regarded to be of human origin, they are considered Smriti (“Tradition”; literally “Recollection”) as distinct from the earlier Vedic literature, which is Shruti (“Revelation”; literally “Which Is Heard”).