Text:

तं दुर्दर्शं गूढमनुप्रविष्टं गुहाहितं गह्वरेष्ठं पुराणम् ।
अध्यात्मयोगाधिगमेन देवं मत्वा धीरो हर्षशोकौ जहाति ॥ १२ ॥

taṃ durdarśaṃ gūḍhamanupraviṣṭaṃ guhāhitaṃ gahvareṣṭhaṃ purāṇam |
adhyātmayogādhigamena devaṃ matvā dhīro harṣaśokau jahāti || 12 ||

12. Contemplating with a concentrated mind, weaned from all external objects on the atman, ancient, hard to see, lodged in the inmost recess, located in intelligence, and seated amidst miserable surroundings, the intelligent man renounces joy and grief.

Shankara’s Commentary:

The atman which you wish to know is hard to see, being extremely subtle, lodged in the inmost recess, being concealed by the modifications of consciousness, caused by worldly objects. Located in intelligence (being realised, as if there lodged) and seated amidst manifold miseries. Being lodged in the inmost recess and located in intelligence, he is seated amidst miseries; (being thus seated he is hard to see) dwelling on that ancient atman, with a mind weaned from all external objects and concentrated on the atman, the intelligent man renounces joy and grief, as there is neither superiority nor inferiority for the atman.