योगवासिष्ठः yogavāsiṣṭhaḥ - book-5, chapter-52, verse-58

मृगतृष्णाक्रमेणैषा भावना व्यर्थभाविनी ।
भावस्तस्यामसत्यायां यः सोऽयमिति संभ्रमः ॥ ५८ ॥

mṛgatṛṣṇākrameṇaiṣā bhāvanā vyarthabhāvinī ,
bhāvastasyāmasatyāyāṃ yaḥ so'yamiti saṃbhramaḥ 58

58. mṛgatṛṣṇākrameṇa eṣā bhāvanā vyarthabhāvinī bhāvaḥ
tasyām asatyāyām yaḥ saḥ ayam iti saṃbhramaḥ

58. eṣā vyarthabhāvinī bhāvanā mṛgatṛṣṇākrameṇa bhāvaḥ
tasyām asatyāyām yaḥ saḥ ayam iti saṃbhramaḥ

58. This conception (bhāvanā) is like a mirage, creating futility. The sense of reality ("this is that") that arises regarding that unreal conception is sheer delusion.

Words meanings summery:

• मृगतृष्णाक्रमेण (mṛgatṛṣṇākrameṇa) - by the method of a mirage, like a mirage

• एषा (eṣā) - Refers to bhāvanā. (this, this one)

• भावना (bhāvanā) - Refers to mental fabrication or mental state. (conception, imagination, thought, mental creation)

• व्यर्थभाविनी (vyarthabhāvinī) - Describing bhāvanā as futile. (futile, creating meaninglessly, having useless thoughts, producing useless results)

• भावः (bhāvaḥ) - The sense of reality or existence. (existence, state, being, idea, notion)

• तस्याम् (tasyām) - Refers to asatyāyāṃ. (in that, upon that)

• असत्यायाम् (asatyāyām) - Refers to the unreal nature of the "bhāvanā" or mental construct. (in the unreal, in the non-existent, in falsehood)

• यः (yaḥ) - Refers to bhāvaḥ. (who, which)

• सः (saḥ) - Correlative to yaḥ, referring to bhāvaḥ. (that, he)

• अयम् (ayam) - Part of the phrase "this is that" (saḥ ayam). (this, he)

• इति (iti) - Enclosing the "this is that" (saḥ ayam) statement. (thus, so, marking direct speech or quotation)

• संभ्रमः (saṁbhramaḥ) - confusion, delusion, bewilderment, agitation

Words meanings and morphology

मृगतृष्णाक्रमेण (mṛgatṛṣṇākrameṇa) - by the method of a mirage, like a mirage

(noun)

Instrumental, masculine, singular of mṛgatṛṣṇākrama

mṛgatṛṣṇākrama - the course/method of a mirage, like a mirage

Compound. mṛgatṛṣṇā (mirage) + krama (course, method).

Compound type : tatpuruṣa (mṛgatṛṣṇā+krama)

• mṛgatṛṣṇā – mirage (lit. deer's thirst)
  noun (feminine)
  mṛga (deer) + tṛṣṇā (thirst).
• krama – course, order, method, way
  noun (masculine)
  From root kram (to step, go).
  Root: kram (class 1)

एषा (eṣā) - Refers to bhāvanā. (this, this one)

(pronoun)

Nominative, feminine, singular of etad

etad - this, this one

Demonstrative pronoun, feminine nominative singular.

भावना (bhāvanā) - Refers to mental fabrication or mental state. (conception, imagination, thought, mental creation)

(noun)

Nominative, feminine, singular of bhāvanā

bhāvanā - conception, imagination, thought, feeling, cultivation, mental activity, producing, causing to be

From root bhū (to be) in the causative, + ana suffix.

Root: bhū (class 1)

व्यर्थभाविनी (vyarthabhāvinī) - Describing bhāvanā as futile. (futile, creating meaninglessly, having useless thoughts, producing useless results)

(adjective)

Nominative, feminine, singular of vyarthabhāvinī

vyarthabhāvin - causing futility, producing meaninglessly, having vain thoughts

Agent noun/adjective from vyartha + bhāvayat (causative present participle of bhū).

Compound of vyartha (futile) and bhāvin (being, causing to be). Feminine form.

Compound type : tatpuruṣa (vyartha+bhāvin)

• vyartha – futile, useless, vain, meaningless
  adjective
  vi + artha.
  Prefix: vi
• bhāvin – being, existing, causing to be, producing, contemplating
  adjective (masculine)
  Present active participle (from causative of bhū).
  From root bhū (to be) in causative form, with in suffix. Feminine bhāvinī.
  Root: bhū (class 1)

Note: Agrees with bhāvanā.

भावः (bhāvaḥ) - The sense of reality or existence. (existence, state, being, idea, notion)

(noun)

Nominative, masculine, singular of bhāva

bhāva - existence, being, state, nature, disposition, sentiment, idea, concept

From root bhū (to be).

Root: bhū (class 1)

तस्याम् (tasyām) - Refers to asatyāyāṃ. (in that, upon that)

(pronoun)

Locative, feminine, singular of tad

tad - that, that one

Demonstrative pronoun, feminine locative singular.

असत्यायाम् (asatyāyām) - Refers to the unreal nature of the "bhāvanā" or mental construct. (in the unreal, in the non-existent, in falsehood)

(adjective)

Locative, feminine, singular of asatyā

asatyā - unreal, false, non-existent, untruth

a (negation) + satyā (true). Feminine form.

Compound type : nañ-tatpuruṣa (a+satyā)

• a – not, un-, non-
  indeclinable
  Particle of negation.
• satyā – real, true, existent, truth
  adjective (feminine)
  Feminine form of satya. From sat (being, existing).
  Root: as (class 2)

Note: Agrees with tasyām.

यः (yaḥ) - Refers to bhāvaḥ. (who, which)

(pronoun)

Nominative, masculine, singular of yad

yad - who, which, what

Relative pronoun, masculine nominative singular.

सः (saḥ) - Correlative to yaḥ, referring to bhāvaḥ. (that, he)

(pronoun)

Nominative, masculine, singular of tad

tad - that, that one

Demonstrative pronoun, masculine nominative singular.

अयम् (ayam) - Part of the phrase "this is that" (saḥ ayam). (this, he)

(pronoun)

Nominative, masculine, singular of idam

idam - this, this one

Demonstrative pronoun, masculine nominative singular.

इति (iti) - Enclosing the "this is that" (saḥ ayam) statement. (thus, so, marking direct speech or quotation)

(indeclinable)

संभ्रमः (saṁbhramaḥ) - confusion, delusion, bewilderment, agitation

(noun)

Nominative, masculine, singular of saṃbhrama

saṁbhrama - confusion, delusion, error, bewilderment, agitation, haste

From root bhram (to wander, err) with upasarga sam.

Prefix: sam

Root: bhram (class 1)