योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-136, verse-15

तदेकत्वं ययौ साम्याद्भूताकाशेन चेतनम् ।
तदास्पदेन तत्राथ वायुना चैकतां ययौ ॥ १५ ॥

tadekatvaṃ yayau sāmyādbhūtākāśena cetanam ,
tadāspadena tatrātha vāyunā caikatāṃ yayau 15

15. tat ekatvam yayau sāmyāt bhūtākāśena cetanam
tadāspadena tatra atha vāyunā ca ekatām yayau

15. tat cetanam bhūtākāśena sāmyāt ekatvam yayau
atha tatra tadāspadena ca vāyunā ekatām yayau

15. That consciousness (cetanam) attained unity with the elemental space (bhūtākāśa) by virtue of its similarity. Then, finding its foundation there, it achieved unity with the air.

Words meanings summery:

• तत् (tat) - that (consciousness) (that, it)

• एकत्वम् (ekatvam) - oneness, unity, singularity

• ययौ (yayau) - went, attained, reached

• साम्यात् (sāmyāt) - from similarity, due to equality

• भूताकाशेन (bhūtākāśena) - with elemental space

• चेतनम् (cetanam) - consciousness, conscious being

• तदास्पदेन (tadāspadena) - by that support, with that as a foundation

• तत्र (tatra) - there, in that place

• अथ (atha) - then, now, moreover

• वायुना (vāyunā) - by air, with air

• च (ca) - and, also

• एकताम् (ekatām) - oneness, unity, singularity

• ययौ (yayau) - went, attained, reached

Words meanings and morphology

तत् (tat) - that (consciousness) (that, it)

(pronoun)

Nominative, neuter, singular of tad

tad - that, it

Note: Refers to cetanam (consciousness).

एकत्वम् (ekatvam) - oneness, unity, singularity

(noun)

Accusative, neuter, singular of ekatva

ekatva - oneness, unity, singularity

Derived from eka (one) with suffix -tva (abstract noun forming suffix)

ययौ (yayau) - went, attained, reached

(verb)

3rd person , singular, active, perfect (liṭ) of yā

Perfect tense, 3rd person singular, active voice of root yā-

Root: yā (class 2)

साम्यात् (sāmyāt) - from similarity, due to equality

(noun)

Ablative, neuter, singular of sāmya

sāmya - similarity, equality, sameness

Derived from sama (equal) with suffix -ya (abstract noun forming suffix)

भूताकाशेन (bhūtākāśena) - with elemental space

(noun)

Instrumental, masculine, singular of bhūtākāśa

bhūtākāśa - elemental space, the subtle element of ether (ākāśa)

Compound of bhūta and ākāśa

Compound type : tatpurusha (bhūta+ākāśa)

• bhūta – element, being, past
  noun (neuter)
  Past Passive Participle
  Derived from root bhū (to be, to exist)
  Root: bhū (class 1)
• ākāśa – space, ether, sky
  noun (masculine)

चेतनम् (cetanam) - consciousness, conscious being

(noun)

Nominative, neuter, singular of cetana

cetana - consciousness, conscious, sentient

Derived from root cit (to perceive, understand)

Root: cit (class 1)

Note: The subject of the sentence, here referring to a subtle principle of awareness.

तदास्पदेन (tadāspadena) - by that support, with that as a foundation

(adjective)

Instrumental, neuter, singular of tadāspada

tadāspada - that which has that as its support/foundation

Compound of tad and āspada

Compound type : bahuvrihi (tad+āspada)

• tad – that, it
  pronoun (neuter)
• āspada – place, seat, support, foundation
  noun (neuter)

Note: Modifies or relates to 'it' (consciousness) having 'bhūtākāśa' as its support.

तत्र (tatra) - there, in that place

(indeclinable)

Locative adverb from tad

अथ (atha) - then, now, moreover

(indeclinable)

वायुना (vāyunā) - by air, with air

(noun)

Instrumental, masculine, singular of vāyu

vāyu - air, wind, vital breath

च (ca) - and, also

(indeclinable)

एकताम् (ekatām) - oneness, unity, singularity

(noun)

Accusative, feminine, singular of ekatā

ekatā - oneness, unity, singularity

Derived from eka (one) with suffix -tā (abstract noun forming suffix)

ययौ (yayau) - went, attained, reached

(verb)

3rd person , singular, active, perfect (liṭ) of yā

Perfect tense, 3rd person singular, active voice of root yā-

Root: yā (class 2)