Shloka 231
अक्षरब्रह्मयोगः | Akṣara-Brahma-Yoga
The Yoga of the Imperishable Brahman
सुखमात्यन्तिकं यत्तद् बुद्धिग्राह्म॒मतीन्द्रियम् । वेत्ति यत्र न चैवायं स्थितश्षलति तत्त्वत:
sukham ātyantikaṃ yat tad buddhi-grāhyam atīndriyam | vetti yatra na caivāyaṃ sthitaś calati tattvataḥ ||
阿周那说：那至上的安乐——为清净之智所领受，超越诸根之境——在其中人真实了知（自我）；安住于彼时，此人不再从真实中动摇。
अर्जुन उवाच
Educational Q&A
The verse defines the highest happiness as a suprasensory realization: it is known by refined intellect (buddhi) rather than sense-contact, and when one is firmly established in that truth, one does not fall away or become shaken by changing circumstances.
Arjuna is speaking in the Bhishma Parva context, articulating (in a yogic-philosophical register) the nature of ultimate happiness and steadiness in truth—framing the ideal inner state that remains unmoved even amid the pressures of the impending war.