Agni
Agni — fire — is one of the five mahābhūtas (great elements), typically listed as the third in the sequence: ākāśa (space), vāyu (wind), agni (fire), āpaḥ (water), pṛthivī (earth). In the cumulative account of the gross elements, tejas possesses sound, touch, and form; rūpa (form/color) is its distinctive sensible quality. Thus it is especially apprehended through sight; rūpa is distinctive to tejas, while sound and touch are also present in the gross element. Agni is the universal principle of transformation: wherever heat converts one substance into another — whether fuel into flame, raw food into digestible nutrition, or offering into divine acceptance — Agni is at work.
In Vedic tradition and Śrī Vaiṣṇava ritual, Agni holds a central place. The entire Vedic sacrificial system (yajña) is predicated on Agni as the divine intermediary: fire is the divine priest (ṛtvij, literally 'worshipper at the right time') who receives offerings (āhuti) poured into it and transmits them to the gods. The very first verse of the Ṛgveda opens with the invocation of Agni: 'agniṃ īḷe purohitaṃ yajñasya devam ṛtvijam / hotāraṃ ratnadhātamam' — 'I praise Agni, the household priest, the divine minister of the sacrifice, the invoker, the greatest bestower of treasure.' In Śrī Vaiṣṇava practice, agni-kārya (homam/fire ritual) precedes significant sacraments: temple rituals, saṃskāras, the installation of divine images, and pañcasaṃskāra ceremonies.
Within the body, Agni appears as jāṭharāgni — the digestive fire in the stomach and small intestine that transforms food into prāṇa and sustains the living body. The Bhagavad Gītā declares: 'ahaṃ vaiśvānaro bhūtvā prāṇināṃ deham āśritaḥ / prāṇāpāna-samāyuktaḥ pacāmy annaṃ catur-vidham' (15.14) — 'I have become the cosmic fire (Vaiśvānara) and, dwelling in the bodies of living beings, combined with prāṇa and apāna, I digest the four types of food.' The Bṛhadāraṇyaka Upaniṣad's Antaryāmī Brāhmaṇa similarly identifies Bhagavān as the antaryāmin (inner controller) of Agni, making Agni Bhagavān's body and instrument.