योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-94, verse-84

याति तेजस्यनोजस्त्वं तमस्योजःप्रधानताम् ।
उलूकवत्पिशाचाद्या आश्चर्यं तत्स्वभावतः ॥ ८४ ॥

yāti tejasyanojastvaṃ tamasyojaḥpradhānatām ,
ulūkavatpiśācādyā āścaryaṃ tatsvabhāvataḥ 84

84. yāti tejasi anojastvam tamasi ojaḥpradhānatām
ulūkavat piśācādyāḥ āścaryam tat svabhāvataḥ

84. tejasi anojastvam yāti tamasi ojaḥpradhānatām
ulūkavat piśācādyāḥ tat āścaryam svabhāvataḥ

84. One becomes devoid of vigor in light, but achieves dominance of vigor in darkness. Beings such as owls and ghosts (piśācādyāḥ) exhibit this; it is astonishing, as it is simply their intrinsic nature (svabhāva).

Words meanings summery:

• याति (yāti) - becomes, obtains (goes, moves, becomes, obtains)

• तेजसि (tejasi) - in light, in brightness (daylight) (in light, in brilliance, in energy, in power)

• अनोजस्त्वम् (anojastvam) - devoid of vigor (powerlessness, lack of vigor, weakness)

• तमसि (tamasi) - in darkness (in darkness, in ignorance)

• ओजःप्रधानताम् (ojaḥpradhānatām) - dominance of vigor (predominance of vigor/energy, dominance of strength)

• उलूकवत् (ulūkavat) - like an owl (like an owl, similar to an owl)

• पिशाचाद्याः (piśācādyāḥ) - ghosts (piśācādyāḥ) and similar beings (ghosts and others, spirits etc.)

• आश्चर्यम् (āścaryam) - astonishing (wonder, surprise, astonishing)

• तत् (tat) - it (referring to the preceding statement) (that, it)

• स्वभावतः (svabhāvataḥ) - due to their intrinsic nature (svabhāva) (by nature, naturally, by one's own intrinsic nature)

Words meanings and morphology

याति (yāti) - becomes, obtains (goes, moves, becomes, obtains)

(verb)

3rd person , singular, active, present indicative (laṭ) of √yā

Present active 3rd singular

Parasmaipada, Present tense, Indicative mood

Root: √yā (class 2)

तेजसि (tejasi) - in light, in brightness (daylight) (in light, in brilliance, in energy, in power)

(noun)

Locative, neuter, singular of tejas

tejas - light, brilliance, energy, power, semen

अनोजस्त्वम् (anojastvam) - devoid of vigor (powerlessness, lack of vigor, weakness)

(noun)

Accusative, neuter, singular of anojastva

anojastva - powerlessness, lack of vigor, weakness

Formed with suffix tā (abstract noun) from anojas. anojas = a (privative) + ojas (vigor, power).

Compound type : tatpuruṣa (a+ojas+tva)

• a – not, non-
  indeclinable
  privative prefix
• ojas – vigor, energy, power, strength
  noun (neuter)
• tva – suffix for abstract noun (denoting state or condition)
  indeclinable
  taddhita suffix

तमसि (tamasi) - in darkness (in darkness, in ignorance)

(noun)

Locative, neuter, singular of tamas

tamas - darkness, gloom, ignorance, quality of inertia

ओजःप्रधानताम् (ojaḥpradhānatām) - dominance of vigor (predominance of vigor/energy, dominance of strength)

(noun)

Accusative, feminine, singular of ojaḥpradhānatā

ojaḥpradhānatā - state of having vigor as primary, predominance of vigor

Formed with suffix tā (abstract noun) from ojaspradhāna. ojaspradhāna = ojas (vigor) + pradhāna (predominant).

Compound type : tatpuruṣa (ojas+pradhāna+tā)

• ojas – vigor, energy, power, strength
  noun (neuter)
• pradhāna – chief, principal, predominant, important
  adjective
  From pra-dhā (to place before)
  Prefix: pra
• tā – suffix for abstract noun (denoting state or condition)
  indeclinable
  taddhita suffix

उलूकवत् (ulūkavat) - like an owl (like an owl, similar to an owl)

(indeclinable)

Formed with suffix vat (like, similar to) from ulūka.

पिशाचाद्याः (piśācādyāḥ) - ghosts (piśācādyāḥ) and similar beings (ghosts and others, spirits etc.)

(noun)

Nominative, masculine, plural of piśācādi

piśācādi - ghosts etc., starting with ghosts

ādi (beginning, etc.) after piśāca.

Compound type : tatpuruṣa (piśāca+ādi)

• piśāca – ghost, demon, goblin
  noun (masculine)
• ādi – beginning, and so on, et cetera
  noun (masculine)

Note: Also used as an adjective, meaning 'headed by X'.

आश्चर्यम् (āścaryam) - astonishing (wonder, surprise, astonishing)

(noun)

Nominative, neuter, singular of āścarya

āścarya - wonder, surprise, miracle, astonishing

From ā-ścar (to move towards).

Note: Predicative use.

तत् (tat) - it (referring to the preceding statement) (that, it)

(pronoun)

Nominative, neuter, singular of tad

tad - that, it, he, she

स्वभावतः (svabhāvataḥ) - due to their intrinsic nature (svabhāva) (by nature, naturally, by one's own intrinsic nature)

(indeclinable)

Formed with suffix tas (from, by way of) from svabhāva (intrinsic nature).

Note: Used to express 'by nature'.