The Bṛhadāraṇyaka Upaniṣad (बृहदारण्यकोपनिषद्) — literally the "Great Forest Upanishad" — is the longest of the principal Upanishads and very likely the oldest. It is attached to the Śatapatha Brāhmaṇa of the Shukla Yajurveda and forms the concluding portion of that immense text. Composed mostly in prose with occasional verse, the contains some of the most sophisticated metaphysical dialogues, the most spirited debates, and the most personally affecting passages in the entire Upanishadic literature.
Structure
The Upanishad has six chapters (adhyāyas) divided into a total of forty-seven brāhmaṇas (sections). The opening chapter offers a series of allegorical meditations: the aśvamedha (horse sacrifice) is interpreted not as a literal rite but as a meditation on the cosmos as a horse. The second through fourth chapters contain the famous dialogues of the sage Yājñavalkya. The fifth and sixth gather diverse additional teachings.
The Cycle
The middle of the is dominated by Yājñavalkya — one of the most fully realized human characters in Sanskrit scripture. We meet him in three principal scenes:
The Dialogue with Maitreyī (2.4 and 4.5)
About to renounce household life and depart for the forest, proposes to divide his property between his two wives, Kātyāyanī and Maitreyī. Maitreyī replies with one of the great questions: If the whole earth filled with wealth were mine, would I be immortal through it? "No," he says, "your life would be like the lives of the wealthy; there is no hope of immortality through wealth."
She answers: What I cannot become immortal by, what shall I do with that? Tell me, sir, what you know.
The teaching that follows is among the Upanishad's most lyrical. Not for the sake of the husband is the husband dear, but for the sake of the self. Not for the sake of the wife is the wife dear, but for the sake of the self. In all relationships, in all that we love, what we truly love is the self that manifests through them. The self is the priyatamam, the most beloved, in everything.
The Court of King Janaka (3.1–3.9)
King Janaka of Videha holds a great philosophical contest, offering a thousand cows tied with gold to whichever Brahmin is wisest. immediately tells his pupil to drive the cows home. The other Brahmins protest, and a series of debates follows in which answers each interlocutor in turn — Aśvala the hotṛ priest, Ārtabhāga, Bhujyu, Uddalaka Aruni, the female philosopher Gārgī Vācaknavī, and others.
Gargi presses the hardest. She asks: On what is the warp and woof of the world woven? He answers: on the worlds, the gods, the moon, the heavens, the sun. And on what are those woven? On brahman. And on what is brahman woven? answers: Do not ask too many questions, Gārgī, or your head will fall off. But she persists, and he gives one of the most subtle teachings in the Upanishad — the doctrine of the akṣara, the imperishable, by whose command sun and moon stand apart and the world goes on.
The Teaching to Janaka in Private (4.3–4.4)
The longest single sustained dialogue concerns dream, sleep, and death. When a person sleeps and dreams, what is the light by which he sees? The light of the mind. When the mind is gathered into the ātman in deep sleep, what light remains? The light of the self alone. And at the moment of death, the self draws back its various breaths and faculties as a ripe mango from its stem; it takes a new body as a caterpillar moves from one leaf to the next; nothing of its desires is lost.
This passage is the most detailed and humane account of dying anywhere in the Vedic corpus, and it became the principal source for later Vedantic eschatology.
Aham Brahmasmi
The contains one of the four classical mahāvākyas, the great utterance assigned to the Yajurveda:
अहं ब्रह्मास्मि ।
ahaṃ brahmāsmi "I am brahman."
The phrase occurs in 1.4.10, in a passage describing how in the beginning brahman alone existed and, knowing itself, declared I am brahman. The verse adds that whoever knows this — I am brahman — knows all this. Whoever does not, becomes a paśu (a beast) for the gods.
The Famous Prayer
From 1.3.28 comes one of the most beloved Sanskrit prayers, the Pavamāna mantra:
ॐ असतो मा सद्गमय । तमसो मा ज्योतिर्गमय । मृत्योर्मा अमृतं गमय ॥
oṃ asato mā sad gamaya, tamaso mā jyotir gamaya, mṛtyor mā amṛtaṃ gamaya "From the unreal lead me to the real; from darkness lead me to light; from death lead me to immortality."
It is recited in temples, in school prayers, in interfaith gatherings worldwide, and constitutes for many the single most familiar fragment of Upanishadic scripture.
Significance
The is the great laboratory of Upanishadic thought. Within its 47 sections one finds the analysis of dream and sleep that the Mandukya would later compress, the doctrine of ātman as the most beloved that the Vivekachudamani would expand, the neti neti method of negation that all Advaita would inherit, and a portrait — through , Maitreyi, Gargi, Janaka — of a society in which deep philosophical inquiry was an honored pursuit. For Shankara and the entire Vedantic tradition, the is, with the Chandogya, the first place to which any serious student is sent.