6.21

सुखमात्यन्तिकं यत्तद् बुद्धिग्राह्यमतीन्द्रियम् ।
वेत्ति यत्र न चैवायं स्थितश्चलति तत्त्वतः ॥

sukham ātyantikaṃ yat tad buddhigrāhyam atīndriyam
vetti yatra na caivāyaṃ sthitaś calati tattvataḥ

Kṛṣṇa (कृष्ण) is still speaking. Another yatra (यत्र) in the chain that began at 6.20.

The verse

Where he knows that endless happiness, grasped by the understanding and beyond the senses, and, established there, he does not slip from the truth.

नेपालीमा

जहाँ ऊ त्यो अनन्त सुख चिन्छ, जुन बुद्धिले समातिन्छ र इन्द्रियभन्दा पर छ, र त्यहाँ अडिएर ऊ तत्त्वबाट चिप्लिँदैन।

Where it sits

Rest and contentment were 6.20. This verse adds what he knows there, and that he stays. The chain is still open.

Split: सुखम् + आत्यन्तिकम् + यत् + तत् + बुद्धि-ग्राह्यम् + अति-इन्द्रियम् + वेत्ति + यत्र + न + च + एव + अयम् + स्थितः + चलति + तत्त्वतः

sukham + ātyantikam + yat + tat + buddhi-grāhyam + ati-indriyam + vetti + yatra + na + ca + eva + ayam + sthitaḥ + calati + tattvataḥ

Sanskrit, in depth

The words

देवनागरीWordGrammarSense
सुखम्sukhamaccusative singularhappiness. What he knows.
आत्यन्तिकम्ātyantikamaccusative singularendless, going all the way. Agrees with sukham (सुखम्).
यत्yatnominative or accusative neuterwhich.
तत्tatnominative or accusative neuterthat.
बुद्धि-ग्राह्यम्buddhi-grāhyamaccusative singularto be grasped by the understanding.
अति-इन्द्रियम्ati-indriyamaccusative singularbeyond the senses.
वेत्तिvettipresent, 3rd singularhe knows. From vid (विद्).
यत्रyatraindeclinablewhere.
नnaindeclinablenot.
चcaindeclinableand.
एवevaindeclinableindeed.
अयम्ayamnominative singularthis one. The man.
स्थितःsthitaḥnominative singularstanding, once established.
चलतिcalatipresent, 3rd singularhe moves, he slips.
तत्त्वतःtattvataḥindeclinable, ablative adverbfrom the truth, in reality.

The phrases

सुखम् आत्यन्तिकम् यत् तत् sukham ātyantikaṃ yat tat is the happiness, and the two adjectives say what kind. Grasped by the understanding, beyond the senses. vetti yatra (वेत्ति यत्र) puts the knowing at the same "where" as 6.20.

na ca eva ayam sthitaḥ calati tattvataḥ (न च एव अयम् स्थितः चलति तत्त्वतः) is the second claim. Standing there, this man does not slip from the truth.

yat tat (यत् तत्) before the voiced b (ब्) is recited yattad (यत्तद्). ca eva ayam (च एव अयम्) is caivāyam (चैवायम्). sthitaḥ calati (स्थितः चलति) is sthitaścalati (स्थितश्चलति). ati indriyam (अति इन्द्रियम्) is atīndriyam (अतीन्द्रियम्), i (इ) plus i (इ) becoming ī (ई).

Sanskrit in this line

yat (यत्) and tat (तत्) are the neuter pair, "which … that," agreeing with sukham (सुखम्). Final t (त्) before a voiced consonant is recited as d (द्), so yat tat buddhi (यत् तत् बुद्धि) is yat tad buddhi (यत्तद् बुद्धि). tattvataḥ (तत्त्वतः) is an ablative used as an adverb. The ending --taḥ (तः) on a noun often means "from" and then freezes into "in respect of." Here, "from the truth," meaning he does not slip in reality.

Say it back

What he knows, and what he does not do once he is standing there. If calati (चलति) loses its na (न), the verse says the opposite.