योगवासिष्ठः yogavāsiṣṭhaḥ - book-6, chapter-81, verse-20

दौःस्थित्यकारणं दोषाद्व्याधिर्देहे प्रवर्तते ।
नद्याः प्रावृण्निदाघाभ्यामिवाकारविपर्ययः ॥ २० ॥

dauḥsthityakāraṇaṃ doṣādvyādhirdehe pravartate ,
nadyāḥ prāvṛṇnidāghābhyāmivākāraviparyayaḥ 20

20. dauḥsthityakāraṇam doṣāt vyādhiḥ dehe pravartate
nadyāḥ prāvṛṭ nidāghābhyām iva ākāraviparyayaḥ

20. vyādhiḥ dehe pravartate,
dauḥsthityakāraṇam doṣāt.
nadyāḥ prāvṛṭ nidāghābhyām iva ākāraviparyayaḥ.

20. Disease (vyādhi) manifests in the body, originating from faults or imbalances and causing a state of disequilibrium, just as the appearance of a river undergoes transformation due to the rainy season and summer.

Words meanings summery:

• दौःस्थित्यकारणम् (dauḥsthityakāraṇam) - cause of a bad state, reason for disequilibrium, cause of distress

• दोषात् (doṣāt) - from fault, from defect, due to imbalance

• व्याधिः (vyādhiḥ) - disease, sickness, ailment

• देहे (dehe) - in the body

• प्रवर्तते (pravartate) - manifests, arises, proceeds, occurs

• नद्याः (nadyāḥ) - of the river

• प्रावृट् (prāvṛṭ) - rainy season

• निदाघाभ्याम् (nidāghābhyām) - by summer (and rainy season)

• इव (iva) - like, as, just as

• आकारविपर्ययः (ākāraviparyayaḥ) - change of form, transformation of appearance

Words meanings and morphology

दौःस्थित्यकारणम् (dauḥsthityakāraṇam) - cause of a bad state, reason for disequilibrium, cause of distress

(noun)

Nominative, neuter, singular of dauḥsthityakāraṇa

dauḥsthityakāraṇa - cause of a bad state, reason for disequilibrium

Compound type : tatpuruṣa (dauḥsthitya+kāraṇa)

• dauḥsthitya – bad state, disequilibrium, distress
  noun (neuter)
  Derived from duḥstha (in a bad state) with ṣyañ suffix.
  Prefix: dus
• kāraṇa – cause, reason, instrument
  noun (neuter)
  From root kṛ (to do) with lyuṭ suffix.
  Root: kṛ (class 8)

Note: Used here as predicate.

दोषात् (doṣāt) - from fault, from defect, due to imbalance

(noun)

Ablative, masculine, singular of doṣa

doṣa - fault, defect, imbalance, impurity (in medical context, refers to vāta, pitta, kapha)

From root duṣ (to be bad, to spoil)

Root: duṣ (class 4)

Note: Indicates the cause or origin.

व्याधिः (vyādhiḥ) - disease, sickness, ailment

(noun)

Nominative, masculine, singular of vyādhi

vyādhi - disease, sickness, ailment

From vi + root ādhā (to place upon, to trouble).

Prefix: vi

Root: ādhā (class 3)

देहे (dehe) - in the body

(noun)

Locative, masculine, singular of deha

deha - body

From root dih (to anoint, to grow, to collect).

Root: dih (class 4)

प्रवर्तते (pravartate) - manifests, arises, proceeds, occurs

(verb)

3rd person , singular, middle, present (laṭ) of vṛt

Prefix: pra

Root: vṛt (class 1)

नद्याः (nadyāḥ) - of the river

(noun)

Genitive, feminine, singular of nadī

nadī - river

प्रावृट् (prāvṛṭ) - rainy season

(noun)

Nominative, feminine, singular of prāvṛṣ

prāvṛṣ - rainy season, monsoon

From pra + root vṛṣ (to rain).

Prefix: pra

Root: vṛṣ (class 1)

निदाघाभ्याम् (nidāghābhyām) - by summer (and rainy season)

(noun)

Instrumental, masculine, dual of nidāgha

nidāgha - summer heat, hot season, summer

From ni + root dah (to burn).

Prefix: ni

Root: dah (class 1)

Note: Used in dual to refer to both prāvṛṭ and nidāgha in the simile.

इव (iva) - like, as, just as

(indeclinable)

आकारविपर्ययः (ākāraviparyayaḥ) - change of form, transformation of appearance

(noun)

Nominative, masculine, singular of ākāraviparyaya

ākāraviparyaya - change of form, transformation of appearance

Compound type : tatpuruṣa (ākāra+viparyaya)

• ākāra – form, shape, appearance
  noun (masculine)
  From ā + root kṛ (to do, to make).
  Prefix: ā
  Root: kṛ (class 8)
• viparyaya – change, reversal, inversion, contrary
  noun (masculine)
  From vi + pari + root i (to go).
  Prefixes: vi+pari
  Root: i (class 2)