Kalpa — The Vedāṅga of Ritual Procedure
Kalpa ('rule, regulation, prescribed method, proper form'; from kḷp = 'to be fit, to be in order') is the sixth Vedāṅga — the vast corpus of prescriptive texts (Kalpa Sūtras) that govern the precise execution of Vedic rituals, domestic rites, and social duties. Kalpa is the most practically significant of the Vedāṅgas for ritual life: it tells practitioners exactly how to perform every rite — the order of actions, the mantras to be recited, the materials required, the times, and the alternatives in case of error.
The Kalpa literature is organized into three main branches:
1. Śrauta Sūtras — Manuals for the major public Vedic sacrifices (yāgas) requiring three or more sacred fires: the Agnihotra (daily fire oblation), Darśapūrṇamāsa (new and full moon sacrifices), Soma sacrifices, and the grand Aśvamedha (horse sacrifice) and Rājasūya (royal consecration). Each Vedic śākhā (recension-school) has its own Śrauta Sūtra.
2. Gṛhya Sūtras — Manuals for the domestic (gṛhya) rites performed at the home fire: the saṃskāras (life-cycle rites from conception to death), śrāddha (ancestral offerings), and pākayajñas (simple domestic offerings). The Gṛhya Sūtras are the practical handbook for household Vedic religion.
3. Dharma Sūtras — Texts governing dharma: social duties, varṇāśrama obligations, legal procedures, penances, and the duties of kings. They evolve into the later Dharmaśāstras (law books) like Manu Smṛti.
For Śrī Vaiṣṇavas, the Āgamas (particularly the Pāñcarātra tradition) serve as the living kalpa tradition for temple worship — specifying in elaborate detail the procedures for abhiṣeka (bathing), arcana (flower-offering), naivedyam (food-offering), utsava (festival) procedures, and all other aspects of temple sevā.