Śarīra-Śarīrī — The Doctrine of the Body-Soul Relationship
The śarīra-śarīrī sambandha ('body-soul relationship', śarīra = body, śarīrī = the one who possesses/ensouls the body) is the foundational metaphysical principle of Rāmānuja's Viśiṣṭādvaita Vedānta. It states: Bhagavān Nārāyaṇa is the śarīrī (the ensouling, controlling Self) of all cit (conscious souls, jīvātmans) and all acit (insentient matter/prakṛti), which in turn constitute His śarīra (body/modes). The entire universe — every soul and every particle of matter — is Bhagavān's body. This is not a metaphor. It is the literal ontological structure of existence.
Rāmānuja established this principle through his interpretation of the Antaryāmī Brāhmaṇa (Bṛhadāraṇyaka Upaniṣad 3.7), where Yājñavalkya declares that Brahman dwells within (antaryāmin) earth, water, fire, sky, wind, the sun, the directions, the moon and stars, ether, darkness, light — and within each individual soul — controlling all from within, unseen. Rāmānuja's reading: this pervasive inner-dwelling is the śarīra-śarīrī relationship. Brahman is the antarātman (inner self) of every being; every being is the body of Brahman.
This principle simultaneously explains two seemingly contradictory Upaniṣadic statements: sarvam khalv idaṃ brahma ('all this is indeed Brahman' — unity) and the Upaniṣadic descriptions of the real distinctions between Bhagavān, jīvas, and the world (diversity). In Viśiṣṭādvaita: the universe is non-dual with Brahman (everything is Brahman's body, nothing exists independently of Him) — yet genuinely differentiated (the body is not identical with the soul; jīvas retain their real individuality as Bhagavān's modes). This principle is the 'viśiṣṭa' (qualified/differentiated) in Viśiṣṭādvaita. All three — Bhagavān (Īśvara), souls (cit), and matter (acit) — form one integrated whole: Brahman as the viśiṣṭa (the qualified, differentiated whole of controller + controlled).