Text:

तदेतदिति मन्यन्तेऽनिर्देश्यं परमं सुखम् ।
कथं नु तद्विजानीयां किमु भाति विभाति वा ॥ १४ ॥

tadetaditi manyante’nirdeśyaṃ paramaṃ sukham |
kathaṃ nu tadvijānīyāṃ kimu bhāti vibhāti vā || 14 ||

14. They think of that as this—the indescribable highest bliss. How shall I know that, whether that which shines is seen clearly or not.

Shankara’s Commentary:

That bliss of the knowledge of the atman which is indescribable, highest and which, though beyond the speech and mind of men, under the sway of Prakriti, they, the Brahmins freed from all desire, describe as this, i.e., as something directly perceived; how; i.e., by what process shall I know that bliss: i.e., realise it as thus perceivable by my intelligence, as the sanyasins freed from desire, do? Is that which is luminous of itself an object clearly perceivable by our intelligence or not?