Vedic sacrifices—called yajñas and yāgas—are an ancient institution. One of its varieties is ‘iṣṭi,’ a sacrifice performed with the four priests adhvaryu, āgnīdhra, hotṛ and brahman. (See under each title for details.) The Darśapūrṇamāsa is a prakṛti (an archetype) in this iṣṭi group and is obligatory.

The words ‘darśa’ and ‘pūrṇamāsa’ actually stand for the new-moon and the full-moon days. Hence, the Vedic rites to be performed on these days have also been named ‘Darśa’ and ‘Pūrṇamāsa’. The two are identical in almost all respects except for some minor variations. Consequently, they are often clubbed together and called, ‘Darśapūrṇamāsa.’

The Darśa sacrifice is done on the new-moon day and the day next to it (pratipad). The Pūrṇamāsa is performed on the full-moon day and the following day.

The only difference in the procedure between these two sacrifices is that the puroḍāśa (rice-cake) is offered to Indra and Agni in the Darśa whereas the same is offered to Agni-Soma in the Pūrṇamāsa.

The preliminaries like shaving, bathing and fasting are done by the sacrificer on the day called ‘upavasaha’ (= fasting and living near the fire). This is followed by anvādhāna (offering of three pieces of sacrificial wood into the fire). The other rites to follow are: piṇḍapitṛyajña (obsequial rites for the forefathers up to three generations); usual daily Agnihotra; preparing the curdled milk for offering on the next day; preparing the puroḍāśa (rice-cakes) for offering; repetition of the sāmidhenī verses (eleven verses from the Ṛgveda, mostly from the third Maṇḍala, aimed at kindling the fire); āghāra libation (wherein the adhvaryu pours ghee into the fire moving the spoon all over, with appropriate mantras) and five prayāja and two ājyabhāga oblations (preliminary offerings).

Then, the principle offerings are made with puroḍāśa (rice-cakes) to the accompaniment of puro’nuvākyas (call or invitation to the deities by the hotṛ priest) and yājyās (technical formulae of consecration chanted by the hotṛ priest while the adhvaryu priest offers a libation of ghee).

In the Darśa, eleven offerings of Puroḍāśa kept in small earthen plates are offered to Indra and Agni. In the Pūrṇa-māsa, the offerings are made to Agni and Soma.

This is followed by the sviṣṭakṛt offering (a secondary offering to Agni by whose goodwill the sacrifice has been successfully done) and iḍābhakṣaṇa (eating the portions cut off from all the main offerings) by the priests.

Then comes anuyāja (three supplementary offerings) followed by sūktavāka (speech of adoration by the hotṛ priest) and śaṁyuvāka (formula of benediction, also by the hotṛ priest).

After a few more minor rites like the patnīsaṁyāja (offerings to the consorts of the deities), removal of the yoktra (a belt of muñja grass), prāyaścittas (expiatory rites) and viṣṇukrama (ceremonially taking four steps with appropriate mantras, by the yajamāna or the sacrificer) the whole sacrifice comes to a close.