Bhagavad Gita 8.17
Spoken by Krishna · Verse 17 of 28
सहस्रयुगपर्यन्तमहर्यद्ब्रह्मणो विदुः | रात्रिं युगसहस्रान्तां तेऽहोरात्रविदो जनाः ||१७||
sahasra-yuga-paryantam ahar yad brahmaṇo viduḥ | rātriṃ yuga-sahasrāntāṃ te'ho-rātra-vido janāḥ || 17 ||
Those who know Brahma's Day as a thousand yugas and his Night as a thousand yugas — they know day and night truly.
Word by word (3)
- sahasra-yuga-paryantam ahar yad brahmaṇaḥ viduḥ
- — The day of Brahma that they know extends to a thousand yugas · sahasra = one thousand (sahasra = 1,000). yuga = age, cosmic epoch (yuga = one of the four cosmic ages: Satya/Krita, Treta, Dvapara, Kali — together they form one mahāyuga; a mahāyuga = 4,320,000 human years). paryantam = extending to, reaching to (pari + anta = all the way to the end; paryanta = the extent, the limit). ahar = day (the daylight period — 'ahas' = day). yad = which. brahmaṇaḥ = of Brahma (Brahmā, the Creator — genitive). viduḥ = those who know (from √vid = to know — viduḥ = third person plural perfect, 'those who know'). So: those who know that one day (ahar) of Brahmā extends to a thousand yugas (sahasra-yuga-paryantam). A 'thousand yugas' as Brahmā's day = 1,000 × 4,320,000 = 4,320,000,000 human years. This is the Vedic concept of a 'kalpa' — one half of Brahmā's day (actually the day is called a 'dvi-parārdha' and the calculation varies by tradition, but the meaning is: an inconceivably vast span of time).
- rātriṃ yuga-sahasrāntāṃ / te aho-rātra-vidaḥ janāḥ
- — And the night ending in a thousand yugas / those people know day and night (truly) · rātriṃ = night (accusative). yuga-sahasrāntāṃ = ending in a thousand yugas (yuga-sahasra = thousand yugas; anta = end — 'of thousand-yuga extent'; same duration as the day). te = those (people). aho-rātra-vidaḥ = knowers of day and night (ahas = day; rātra = night; vit = knower; aho-rātra-vit = one who knows the (cosmic) day and night). janāḥ = people. The point: those who truly 'know day and night' are not those who know the 24-hour cycle but those who know Brahmā's cosmic day and night — each of 1,000-yuga duration. This expands the frame of reference to cosmic scale: what is 'day' and 'night' from the perspective of the entire cosmos? V17 gives the answer in numbers that dwarf human history by millions of times, making V16's 'even Brahma's realm returns' concrete: it returns because BRAHMA HIMSELF has a day and night — a cycle — and when his night comes, his realm dissolves (V18).
- V17 in context: cosmic time as a liberation teaching
- — The thousand-yuga teaching establishes the scale of the cosmic cycle, making V16's 'no-return with Me' the only option that is truly final · V17 serves a specific pedagogical function: it makes V16's cosmic claim concrete. 'All worlds return' — but HOW? V17 explains: even Brahma's day, which is an incomprehensibly vast span (4.32 billion years), still ends. His night is equally vast. When his night comes, his world dissolves (V18). When his day comes again, it re-emerges (V18). This is a teaching about the relative nature of even the highest cosmological realms. By establishing the scale of cosmic time (1,000 yugas = one day of Brahma), V17 makes the practitioner realize: even the highest aspirations within this framework are temporary. The yugas of human history — all the achievements, all the civilizations, all the spiritual realizations within a cosmic night — dissolve at Brahma's nightfall. Only the akṣara (V3, V11) beyond Brahma's cycle is truly final. V17's cosmic scale teaching is meant to shift the practitioner's aspiration from the 'long-lasting' to the 'eternal' — from seeking the best position within the cycle to seeking what is beyond the cycle.
Those who know that a day of Brahmā lasts a thousand ages and his night lasts a thousand ages — they truly know day and night.
A modern analogy
A geologist who 'knows' time is one who understands that what seems permanent on a human timescale (mountain ranges, continents) is temporary on a geological timescale. This verse asks for cosmic-scale temporal intelligence: the one who 'knows day and night' is one who understands that what seems permanent on even a cosmological timescale (Brahma's realm, the entire created universe) is temporary on an absolute timescale. The akṣara (Imperishable) is what remains permanent even on this absolute scale.
What it does NOT mean
This verse is not primarily a cosmological lecture about the age of the universe. Its purpose is liberation-oriented: by establishing that even Brahma's day is measured and ends, it makes concrete why the promise that those who attain Me are not reborn is uniquely valuable. If even Brahma's cosmos is temporary, the urgency of seeking what is beyond the cycle intensifies.
Take with you
- The thousand-yuga scale is a contemplative tool: sit with the fact that Brahma's Day = 4.32 billion years. In that span, human civilizations arise and dissolve thousands of times. In the scale of the cosmos, an individual human life is invisible. From this perspective, the urgency of 'remember Me constantly' intensifies: the brief window of this human birth is cosmically rare and cosmically brief — use it for the attainment that escapes rebirth.
- 'Those who know day and night' (aho-rātra-vidaḥ) — the ones who have truly internalized the cosmic scale — are the ones for whom the practice urgency is greatest. Not those who are anxious about mortality but those who have the cosmic perspective: within the vast cycles, this human opportunity is precious.
- This verse is a perspective-expander: when daily concerns feel overwhelming (the meeting, the deadline, the argument), the thousand-yuga frame is available as a perspective reset. 'This is within Brahma's Day — which is 4.32 billion years. Even THAT Day ends. What is truly permanent?' Not dismissal of daily concerns but cosmic perspective on them.
Public-domain translations (5) compare all →
They who know (the true measure of) day and night, know the day of Brahma, which ends in a thousand Yugas, and the night which (also) ends in a thousand Yugas. [4]
Those who know Brahmâ's Day, a thousand ages in extent, and Brahmâ's Night, a thousand ages in ending, they know Day and Night. [5]
Those who know that the day of Brahma is of a thousand ages' duration, and that his night also is of a thousand ages, they know day and night. [6]
If ye know Brahma's Day Which is a thousand Yugas; if ye know The thousand Yugas making Brahma's Night, Then know ye Day and Night as He doth know! [7]
Those who know a day of Brahman to end after one thousand ages, and the night to terminate after one thousand ages, are the persons who know day and night. [9]
This verse speaks to
Where this thread continues
All worlds up to Brahma's realm are subject to return — but those who attain Me, O Arjuna, are not reborn.
At Brahma's dawn, all beings emerge from the unmanifest; at his dusk, they merge back into that same unmanifest.
At the end of each cosmic age, all beings return to My prakriti — at the next dawn, I send them forth again.
Whoever does not turn the cosmic wheel of giving — living only for sense-pleasure — lives in vain.
I taught this imperishable yoga to the sun-god at the dawn of time — it has been passed down through kings ever since.
Whenever dharma declines and adharma rises — I project Myself forth. The divine responds to every crisis.
Verse 17 of 28 · back to Chapter 8