योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-155, verse-54

वामावामशिरःपादविपर्ययविधौ यथा ।
पुंसो न विद्यते शक्तिस्तथा भाव्यन्यथास्थितौ ॥ ५४ ॥

vāmāvāmaśiraḥpādaviparyayavidhau yathā ,
puṃso na vidyate śaktistathā bhāvyanyathāsthitau 54

54. vāmāvāmaśiraḥpādaviparyayavidhau yathā puṃsaḥ
na vidyate śaktiḥ tathā bhāvyanyathāsthitau

54. yathā puṃsaḥ vāmāvāmaśiraḥpādaviparyayavidhau
śaktiḥ na vidyate tathā bhāvyanyathāsthitau

54. Just as a person lacks the power (śakti) to reverse the left and right positions of their head and feet, similarly, there is no power (śakti) to alter the destined (bhāvya) state of things to be otherwise.

Words meanings summery:

• वामावामशिरःपादविपर्ययविधौ (vāmāvāmaśiraḥpādaviparyayavidhau) - in the act of reversing the left and right positions of one's head and feet (in the reversal/arrangement of left and right head and foot)

• यथा (yathā) - just as (just as, as, in which way)

• पुंसः (puṁsaḥ) - for a person (of a man, for a man)

• न (na) - not (not, no)

• विद्यते (vidyate) - exists (exists, is found, is)

• शक्तिः (śaktiḥ) - power (śakti) (power, ability, energy, faculty)

• तथा (tathā) - similarly (similarly, so, thus, in that way)

• भाव्यन्यथास्थितौ (bhāvyanyathāsthitau) - in the state of altering the inherent (destined) condition (in the state of what is destined being otherwise)

Words meanings and morphology

वामावामशिरःपादविपर्ययविधौ (vāmāvāmaśiraḥpādaviparyayavidhau) - in the act of reversing the left and right positions of one's head and feet (in the reversal/arrangement of left and right head and foot)

(noun)

Locative, masculine, singular of vāmāvāmaśiraḥpādaviparyayavidhi

vāmāvāmaśiraḥpādaviparyayavidhi - the act or manner of reversing the left, right, head, and foot

Compound type : tatpuruṣa (vāma+avāma+śiras+pāda+viparyaya+vidhi)

• vāma – left, reverse, adverse, beautiful
  adjective (masculine)
• avāma – not left, right, not adverse, favorable
  adjective (masculine)
• śiras – head, top, peak
  noun (neuter)
• pāda – foot, leg, quarter, ray of light
  noun (masculine)
• viparyaya – reversal, inversion, contrary, error
  noun (masculine)
  derived from pari-i + vi (prefix) + aya
  Prefixes: vi+pari
  Root: i (class 2)
• vidhi – rule, method, ordinance, act, manner, fate
  noun (masculine)
  from dhā (to place) + vi (prefix)
  Prefix: vi
  Root: dhā (class 3)

Note: Compound of several nouns and adjectives ending in 'vidhi' in locative singular.

यथा (yathā) - just as (just as, as, in which way)

(indeclinable)

पुंसः (puṁsaḥ) - for a person (of a man, for a man)

(noun)

Genitive, masculine, singular of puṃs

puṁs - man, person, male, spirit (puruṣa)

Note: Also could be ablative singular. Genitive fits better with 'power of a man'.

न (na) - not (not, no)

(indeclinable)

विद्यते (vidyate) - exists (exists, is found, is)

(verb)

3rd person , singular, ātmanepada, present (laṭ) of vid

present passive/ātmanepada

Root vid (to be, 4th class) or vid (to know, ātmanepada, 7th class, or passive of 2nd/6th class vid to know). Here, 'to exist'.

Root: vid (class 4)

Note: Used in the sense of 'to exist'.

शक्तिः (śaktiḥ) - power (śakti) (power, ability, energy, faculty)

(noun)

Nominative, feminine, singular of śakti

śakti - power, strength, ability, faculty, divine energy, goddess (śakti)

From root śak (to be able).

Root: śak (class 5)

Note: One of the specific terms from the list.

तथा (tathā) - similarly (similarly, so, thus, in that way)

(indeclinable)

भाव्यन्यथास्थितौ (bhāvyanyathāsthitau) - in the state of altering the inherent (destined) condition (in the state of what is destined being otherwise)

(noun)

Locative, feminine, singular of bhāvyanyathāsthiti

bhāvyanyathāsthiti - the state of what is destined or intended being otherwise

Compound type : tatpuruṣa (bhāvya+anyathā+sthiti)

• bhāvya – to be, future, destined, proper
  adjective (neuter)
  Gerundive/Future Passive Participle
  Formed from root bhū (to be).
  Root: bhū (class 1)
• anyathā – otherwise, in a different manner
  indeclinable
• sthiti – state, condition, stability, existence
  noun (feminine)
  From root sthā (to stand).
  Root: sthā (class 1)

Note: Compound ending in locative singular.