योगवासिष्ठः yogavāsiṣṭhaḥ - book-1, chapter-19, verse-16

शैशवं च मनश्चैव सर्वास्वेव हि वृत्तिषु ।
भ्रातराविव लक्ष्येते सततं भङ्गुरस्थिती ॥ १६ ॥

śaiśavaṃ ca manaścaiva sarvāsveva hi vṛttiṣu ,
bhrātarāviva lakṣyete satataṃ bhaṅgurasthitī 16

16. śaiśavaṃ ca manaḥ ca eva sarvāsu eva hi vṛttiṣu
bhrātarau iva lakṣyete satataṃ bhaṅgurasthitī

16. śaiśavaṃ ca manaḥ ca eva hi sarvāsu vṛttiṣu
satataṃ bhaṅgurasthitī bhrātarau iva lakṣyete

16. Indeed, childishness and the mind, in all their activities, always appear like two brothers with unstable dispositions.

Words meanings summery:

• शैशवं (śaiśavaṁ) - childishness, childhood

• च (ca) - and

• मनः (manaḥ) - mind

• च (ca) - and

• एव (eva) - indeed, certainly

• सर्वासु (sarvāsu) - in all

• एव (eva) - indeed, only

• हि (hi) - indeed, for

• वृत्तिषु (vṛttiṣu) - in activities, in dispositions, in modes of being

• भ्रातरौ (bhrātarau) - like two brothers

• इव (iva) - like, as if

• लक्ष्येते (lakṣyete) - appear, are perceived

• सततं (satataṁ) - constantly, always

• भङ्गुरस्थिती (bhaṅgurasthitī) - having an unstable state, unstable, perishable

Words meanings and morphology

शैशवं (śaiśavaṁ) - childishness, childhood

(noun)

Nominative, neuter, singular of śaiśava

śaiśava - childishness, childhood, infant state

Derived from 'śiśu' (child)

च (ca) - and

(indeclinable)

मनः (manaḥ) - mind

(noun)

Nominative, neuter, singular of manas

manas - mind, intellect, thought, heart

च (ca) - and

(indeclinable)

एव (eva) - indeed, certainly

(indeclinable)

सर्वासु (sarvāsu) - in all

(pronoun)

Locative, feminine, plural of sarva

sarva - all, every, whole

एव (eva) - indeed, only

(indeclinable)

हि (hi) - indeed, for

(indeclinable)

वृत्तिषु (vṛttiṣu) - in activities, in dispositions, in modes of being

(noun)

Locative, feminine, plural of vṛtti

vṛtti - activity, mode of being, disposition, function, livelihood

From root vṛt (to exist, to turn)

Root: vṛt (class 1)

भ्रातरौ (bhrātarau) - like two brothers

(noun)

Nominative, masculine, dual of bhrātṛ

bhrātṛ - brother

इव (iva) - like, as if

(indeclinable)

लक्ष्येते (lakṣyete) - appear, are perceived

(verb)

3rd person , dual, passive, present (lat) of lakṣ

Root: lakṣ (class 10)

सततं (satataṁ) - constantly, always

(indeclinable)

Note: Adverbial usage, typically neuter accusative singular.

भङ्गुरस्थिती (bhaṅgurasthitī) - having an unstable state, unstable, perishable

(adjective)

Nominative, masculine, dual of bhaṅgurasthiti

bhaṅgurasthiti - whose state is perishable, unstable disposition

Compound type : bahuvrihi (bhaṅgura+sthiti)

• bhaṅgura – perishable, fragile, breaking easily
  adjective (masculine)
  Derived from root bhañj (to break)
  Root: bhañj (class 7)
• sthiti – state, condition, existence, firmness
  noun (feminine)
  From root sthā (to stand)
  Root: sthā (class 1)

Note: Qualifies 'śaiśavaṃ ca manaś ca' treated as a dual pair, like bhrātarau.