Bhagavad Gita: Chapter 2/Verse 58

यदा संहरते चायं कूर्मोऽङ्गानीव सर्वशः ।
इन्द्रियाणीन्द्रियार्थेभ्यस्तस्य प्रज्ञा प्रतिष्ठिता ॥२- ५८॥

yadā saṃharate cāyaṃ kūrmo'ṅgānīva sarvaśaḥ ।
indriyāṇīndriyārthebhyastasya prajñā pratiṣṭhitā ॥2- 58॥

And when one withdraws all the senses from the objects of the senses like limbs of the tortoise.  Of that, understanding is established. 


Word-for-word translations

yadā (relative adverb) (indeclinable) = when 

saṃharate (present tense, 3rd person, singular) = one withdraws 

ca (conjunction) (indeclinable) = and

ayam (demonstrative pronoun, masculine, nominative, singular) = the

kūrmas (masculine, nominative, singular) = tortoise

aṅgāni (neuter, nominative, plural) = limbs

iva (preposition) (indeclinable) = like (follows word to which it refers) 

sarvaśas (adverb) (indeclinable) = all


indriyāṇi (neuter, accusative, plural) = senses 

indriyārthebhyas (indriya + arthebhyas) (compound) (masculine, ablative, plural) = from the object of the senses 

tasya (pronoun, 3rd person, masculine, genitive, singular) = of that

prajñā (feminine, nominative, singular) = understanding 

pratiṣṭhitā (feminine, nominative, singular) = established


Commentary 

Relative and correlative markers in this verse really help in the breaking down this verse into manageable parts. Just like the preposition "iva" meaning "like" in this verse. The conjunction "ca" meaning "and" in this verse is often left out in previous translations. The demonstrative pronoun often means "this" or "that", but in the verse it means "the".