योगवासिष्ठः yogavāsiṣṭhaḥ - book-1, chapter-20, verse-37

तावदेव विवल्गन्ति रागद्वेषपिशाचकाः ।
नास्तमेति समस्तैषा यावद्यौवनयामिनी ॥ ३७ ॥

tāvadeva vivalganti rāgadveṣapiśācakāḥ ,
nāstameti samastaiṣā yāvadyauvanayāminī 37

37. tāvadeva vivalganti rāgadveṣapiśācakāḥ na
astam eti samastā eṣā yāvat yauvanayāminī

37. rāgadveṣapiśācakāḥ tāvadeva vivalganti,
yāvat eṣā samastā yauvanayāminī na astam eti.

37. The demons of attachment (rāga) and aversion (dveṣa) leap and rage only so long; as long as this entire night of youth (yauvanayāminī) has not yet passed, they do not go to rest.

Words meanings summery:

• तावदेव (tāvadeva) - only so long, just so long, exactly that much

• विवल्गन्ति (vivalganti) - leap, bound, dance, rage, become rampant

• रागद्वेषपिशाचकाः (rāgadveṣapiśācakāḥ) - demons of attachment and aversion

• न (na) - not, no

• अस्तम् (astam) - goes to rest, sets (when combined with 'eti') (setting, disappearance, going home)

• एति (eti) - sets, disappears (when combined with 'astam') (goes, comes, approaches)

• समस्ता (samastā) - entire, whole, complete, all

• एषा (eṣā) - this, this one

• यावत् (yāvat) - as long as, as far as, until

• यौवनयामिनी (yauvanayāminī) - night of youth

Words meanings and morphology

तावदेव (tāvadeva) - only so long, just so long, exactly that much

(indeclinable)

tāvat (so much) + eva (only)

विवल्गन्ति (vivalganti) - leap, bound, dance, rage, become rampant

(verb)

3rd person , plural, active, present (laṭ) of vivalg

Present Tense, Parasmaipada

root: valg, class: 1 (bhvādi), upasarga: vi

Prefix: vi

Root: valg (class 1)

रागद्वेषपिशाचकाः (rāgadveṣapiśācakāḥ) - demons of attachment and aversion

(noun)

Nominative, masculine, plural of rāgadveṣapiśācaka

rāgadveṣapiśācaka - demons of attachment and aversion

Compound type : dvandva-tatpuruṣa (rāga+dveṣa+piśācaka)

• rāga – attachment, passion, desire
  noun (masculine)
• dveṣa – aversion, hatred, dislike
  noun (masculine)
• piśācaka – a demon, an evil spirit, fiend
  noun (masculine)

Note: Refers to the personification of attachment and aversion as demons.

न (na) - not, no

(indeclinable)

अस्तम् (astam) - goes to rest, sets (when combined with 'eti') (setting, disappearance, going home)

(indeclinable)

Note: Used with 'eti' to form the idiom 'astam eti' meaning 'to set' or 'to disappear'.

एति (eti) - sets, disappears (when combined with 'astam') (goes, comes, approaches)

(verb)

3rd person , singular, active, present (laṭ) of i

Present Tense, Parasmaipada

root: i, class: 2 (adādi)

Root: i (class 2)

समस्ता (samastā) - entire, whole, complete, all

(adjective)

Nominative, feminine, singular of samasta

samasta - entire, whole, complete, all

Past Passive Participle (sometimes used as adjective)

root: as (to be), upasarga: sam, suffix: -ta

Prefix: sam

Root: as (class 2)

Note: Agrees with 'yauvanayāminī'.

एषा (eṣā) - this, this one

(pronoun)

Nominative, feminine, singular of etad

etad - this, this one

Note: Agrees with 'yauvanayāminī'.

यावत् (yāvat) - as long as, as far as, until

(indeclinable)

यौवनयामिनी (yauvanayāminī) - night of youth

(noun)

Nominative, feminine, singular of yauvanayāminī

yauvanayāminī - night of youth

Compound type : tatpuruṣa (genitive) (yauvana+yāminī)

• yauvana – youth, youthfulness
  noun (neuter)
  derived from yuvan (young) with suffix -a
• yāminī – night
  noun (feminine)

Note: Metaphorical usage.