Source: here.
From Jan Gonda’s ‘The Dual Deities in the Religion of the Veda’
Ritualistically, the so called dvandvas, that is copulative compounds indicating double divinities/deities, have significance in sacrificial roles. The grammatical manifestations of such are often multi-variegated: preservation of accents, case declensions, etc.
A critical gloss of certain panegyric or propitiatory hymns can be revealing.
Unitary identity
For example in ṚV 7.12.3, Agni is coordinated with Varuṇa-Mitra, functionally conveying the latter duality is a representation of the former, though this need not signify a functional devāta-dvandva.
Some double deities, ie Vedic Duality, can be conceived of as unities. We see KS 10.2.126 agnīṣomau vai brāhmaṇsya svā devatā, Agni-Soma are the Brahmin’s own deity. They are spoken of as if they are single divine persons due to which enumeration customs become prominent. For eg, at the sacrificial stake in the sanguinary+++(=bloody)+++ rite, at VS 24.1 the authors enumerate that single divinities are allotted 2 goats (even to the twin Aśvins) but the dual deity saumāpauṣnaḥ is allotted one goat (functionally a dualité-unité ie single victim to a double deity).
Roles and traits
We see an enumeration of gods with naturalistic features for the expedience of a successful ritual - in this case seasons. The Vājasaneyins say after the aśvamedha, seasonal sacrifices should take place to honor the gods, Indra-Viṣṇu in the cool season, Indra-Varuṇa in autumn, etc.. Liturgical arrangement of enumerated dualité-unité deities may show juxtaposition with their component members and the order of their combinations may differ for ritualistic expediencies. ŚB 1.8.3.1 says the full-moon offering goes to Agni-Soma, the new moon offering to Indra-Agni.
One may note that a double deity may have other functionary roles. Mitrāvaruṇau holds the office of the hotr, Bṛhaspati the udāgatr, the twin Aśvins, the adhvaryu. Combinatorial examples don’t always indicate natural affinities between the deities, nor do all appear in compounds.
The aforementioned affinities do sometimes manifest however in which case antipodal or complementary characteristics of each component deity in a duality may be looked at. Rudra is known to have also have ghorā tanu aspect and this twofold character manifests later in post-Vedic conceptions of Viṣṇu and Śiva with the theme of protector and destroyer a vestigial remnant of ‘ambivalence’ in the co-ordination of Vedic gods.+++(really?)+++ One eg is that of Mitra-Varuṇa where the former is a benevolent maintainer while the latter is the punishing guardian.
A divine personnage can have a ‘double’ character ie Indra in ŚB 5.3.5.27 is seen as both a kṣatriya & a sacrificer (…indra bhavati yac ca kṣatriyo u ca yajamānaḥ). In ŚB 3.2.4.8, a pair can be seen as having the same source ie milk & gold derive from Agni’s seed agniretasa
We may see very rare dual deities like vāyusavitṛ or vāyosavitṛ invoked for ritual specificity and that perhaps a certain deity had a limited cult. There are instances of a deity being co-oridnated with a non-deity ie indrākutsā where Kutsa can be his charioteer ṚV 5.31.9.
Some extended commentary on the preservation of Vedic dual deities in post-Vedic pantheon/theophany.
Language markers
The Vedic ubhaya (of both kinds) is known to accompany pair-systems (widely attested in ancient IE enumerations such as symmetry in the human body, heaven & earth, day & night, land & sea, tribal/war parties) is cognate with the Greek ἄμφω meaning both emphasizing pair unity.
The particle ca can be used by the author to emphasize a form of association along with markers like dvau (Sāyaṇa explains Mitra-Varuṇa are called dvā-janā ie dvau because they are conjointed/united kings ie sahitau). Arrangement of entities in enumerated pairs is seen frequently.
Syntactic constructions like copulative asyndetons+++(=omission of the conjunctions that ordinarily join coordinate words or clauses)+++ and compounds show that the Vedic authors had a proclivity to explicate complementary pairs - ie both arms ubhāhyāṃ hastābhyām, hair and beard keśa-śmaśru, both testiscles ubhe āṇḍyau, 2 horses of a chariot dvayam agne rathino.
Two conflicting parties in the ṚV are indicated as ‘both battle-arrays’: ṚV 2.12.8 yaṃ krandasī saṃyatī vihvayete pare avara ubhayā amitrāḥ…nānā havete sa janāsa indraḥ ie Whom Indra the 2 battle arrays coming together call upon both foes, the farther and the nearer.
We note such dichotomies as classes of the lower & higher gods devair avaraiḥ paraiś ca in TS 6.4.6.2. ŚB 13.2.11.2 gives the dichtomy of those gods w/hails of svāhā either BEFORE or AFTER their names or soma vs non-soma drinkers, oblation eaters vs non oblation eaters, etc.
Likewise w/the gods & men, we have devas & asuras. Though antagonistic, the ŚB reminds us that they both sprang from Prajāpati & are fraternal. They both competed for the favor of the gāyatrī. Their realms: waxing-moon/heavens/mind-devas; waning-moon/earth/vāc-asuras.
This type of primordial religious dualism between dichotomies, complementary pairs underlies Vedic thought (ritual/spiritual pedigree; religious merits; sacrificial offerings) and in dual organization of regional & Vedic mythemes/deities, sociopolitical units, natural phenomena
Twins
Mention must be made of the problem of twins in IE mythemes as they should be distinguished from double deities. The rare occurrence of twins lends itself to notions of them being progenitors of cities, patrons of fertility and the rains. Co-ordiantion of twins with a solar deity - for eg, the Hellenic twins the Disoscuri with Helena & the twin Ásvins with Sūryā. Twins can be associated with medical powers, guardians of righteousness. Twins are spoken of in the singular case rather than the dual signifying their oneness (unlike deity dualities).
In dual deities & divine twins, the latter are distinguished by their common origin not common function. This may explain why the naming scheme of the twins of the Mithras and Romans were similar ie Cautes & Cautopates and Romulus & Remus / Mutunus & Tutunus / Picumnus & Pilumnus.
Mythic twins can be identified by certain taboos identified at their birth & with their mother - ie one twin is the product of mother’s intercourse with a man & other with an evil spirit (Polydecues son of Zeus vs Castor son of Tyndareos); purfication rites vs primogeniture rights, etc.
The author notes the ancient Iranian figure Nanhaithya corresponding to Vedic Nāsatya (epithet for the twin Aśvins) and postulates that notions transference of this ancient myth to the Vedic twins to be circumspect. One notes the epithet applied in the dual to them vasū rudrā. Yāska himself noted that the twin Aśvins are both praised though their deeds were identical. The theme of twins being endowed with medical powers is noted when he mentions they are physicians. Like the Greek Dioscuri, the Aśvins are said to be young, beautiful, and virile. The parentage of the twins is said to be from Dyauṣpitṛ - but elswhere they are said to be borne of the mother Sindhu or of Saraṇyu (daughter of Tvaṣṭr). Even Roman analogues feature inconsistency in parentage. Like the Dioscuri, they rescue those stranded in the sea.
One final comment on the co-ordination of the twins can be noted that within Vedic rite, these dvidevatagraha-s in the Soma sacrifice are juxtaposed with aindra-vāyava & maitra-varuṇa-grahas indicating some level of influence of twins with respect to double deities.
Divine triunes are much more rare than divine dualities.
General duality
The famous motif of a complementary group, the gods & men, are given extensive treatment by the authors with the ŚB 7.5.2.27 saying ubhayeṣāṃ haitad devamanuṣyāṇāṃ cakṣuḥ the sun is said to be the eye of both gods & men. The divine are borne from metres while humans the womb.
ṚV 8.38.1, interestingly conveys, Agni as being the intermediary of both the heavenly abode & sacrificial place respectively the spheres of the gods & men. Prajāpati represents both gods & men. ŚB doctrines expound that the north is quarter of men, the east that of the gods,… the north-east of BOTH gods & men. The complementary pair of both the gods & ’learned brahmaṇa-s’ explicated by ŚB 3.3.3.4.20 they are both TWO kinds of gods. A distinction is made in ṚV 6.19.13 btwn those of Āryan descent & foreign foes, ubhayāṃ amitrān dasā vṛtraṇy aryā ca
Such dichotomic and complementary combinatorial enumerations are said to have facilitated the compiling of exhaustive lists of qualities and came to be highly characteristic of traditional Indian thought- a highly preserved feature in liturgic Indian literature.
The twofold character of entities & the idea of a duality acting as a unity underlies Vedic thought. In the creation hymn of the ṚV asat & sat are co-oordinated to chaos & cosmos while in the BĀU, Yājñavalkya expounds that the body is one half of oneself (split-pea analogy).
Notwithstanding ritual function, that dualities can manifest sociologically and in natural phenomena was explained through presence of pairs. For example ŚB 1.6.3.30 explains that many creatures have teeth on either side since enunciate a ṛc via BOTH anuvākyā & yājyā.
In other texts, divine pairs are said to be guardians of a realm: Yama-Mṛtyu, South; Mitra-Varuṇa, West; Soma-Rudra, North; Bṛhaspati-Indra, zenith, etc. It is theorized that these parallel double invocations made orisons more effective in situations of exigency.
Whereas it has been seen that dual deities can act as unit, in some cases, via mithuna (completeness, here), component deities can reciprocally augment the other in a duality. Such efficacious pairings might be construed to remedy latent evils or assist in ritual techniques.
The TS 1.6.8.2 illustrates how exactly a pair can manifest in ritual: ‘weapons’ of sacrifice can make a yājñānuvakyā, thus when preparing the fire one should pronounce aloud one of the yaju-s when placing the kindling stick & set the other in silence. ‘Pairing’ in rites is common.
The significance of double occurrence, performance, doubling of various aspects in ritual activities is not lost on since they serve to duplicate the results of a sacrifice: bifurcate sacrificial post for Mitrāvaruṇau, coexistence of 2 sāmans rathantara & bṛhat, etc.
Stomas have a dual nature (even & odd) hence apt for procreation. In the ṚV the metre Gāyatrī (for the brahmaṇa) & Triṣṭubh (for the kṣatriya) are complementary pairs when if both recited confers vitality to the body (vitality via the former metre to the body via the latter)
The worship and activities done by a man are twofold in nature in order to maintain the universe: singing of praises & utterance of worship= sacrifice; sautrāmaṇī is both vegetarian & bloody; priests need both a post & wooden sword and noblemen, chariot & arrows (ŚB 1.2.4.1).
A note is made on a double sattra (dvayaṃ sattram), of whose performance confers commensurate merit/welfare, is co-oordinated to the Āditya-s and the Aṅgiras’ (both borne of Prajāpati ‘in the beginning’), the former who has a 21 day rite, while the latter has a 12 day rite.
The twofold natures of metre are given some treatment: the gāyatrī (composed gāyatra+ āmahīyava) & bṛhatī (composed of raurava+ yaudhaājaya) while Indra invoked the metres kakubh and uṣṇih when lifting the vajra to kill Vṛtra (both which arose from Indra’s feet).
The hotṛ and the hotṛaka-s follow a scheme during chanting: the former recites 2 ukthas of 1 hymn each, while the latter recites 1 uktha of 2 hymns each. The former is sad to be the sun, while the latter its rays because rays are said to be composed of 2 colors.
Ritual and explanatory use
Anatomical parts of the sacrificial horse too are co-oordinated with dual deities (among the 131 deities assigned to each part) for eg., Heaven-Earth, eyelashes; Agni-Soma, 6th rib; Mitra-Varuṇa, groins; Indra-Bṛhaspati, the thighs, and so on.
In times of war, it was thought by the Vedic Aryans that the invocation of Indra-Varuṇa would grant him favor against his foes: see the 2nd hemistitch of ṚV 7.83.1 ..dāsā ca vṛtrā hatam āryāṇi ca sudāsam indrāvaruṇāvasāvatam (slay the anti-Aryans & give favor to Sudās)
During the constriction of the fire-altar, the Vedic ancillaries say that the invocation of agnāvaiṣṇavyarcā (Agni-Viṣṇu) whilst ladling the ghee produces a stream of wealth since both deities are associated with this quality.
It seems ancient Indian physicians also adopted the scheme of double deities to explain some concepts ie Suśruta mentions that blood is of the nature of Agni-Soma.
Just as the trifunctional theory explains the different 3 estates in IE society, we note in Vedic dualities that the sacerdotes+++(=Rtviks)+++ belong to mitrāvaruṇau & the noblemen to Indrāvaruṇau KS 12.1.162 payasyayā yajetāmayāvī maitrāvaruṇī brāhmaṇasya syād aindrāvaruṇi rājanyasya
During the thread investiture initiation rite, the teacher conveys to the initiate a consignment of deities with ritual function and mentions the dual deity Indrāgnī as a preeminent divine entity. The ŚB 11.5.4.3 states that the student is committed to Prajāpati-Savitṛ.