Kaṭha Upaniṣad 248

248

katham asau boddhavyaḥ kiṃ vā tadavabodhe prayojanam ity ucyate -- indriyāṇāṃ śrotrādīnāṃ svasvaviṣayagrahaṇaprayojanena svakāraṇebhya ākāśādibhyaḥ pṛthagutpadyamānānām atyantaviśuddhāt kevalāc cinmātrātmasvarūpāt pṛthagbhāvaṃ svabhāvavilakṣaṇātmakatām, tathā teṣām evendriyāṇām udayāstamayau cotpattipralayau jāgratsvāpnāvasthāpekṣayā nātmanas tāv iti matvā jñātvā vivekato dhīro dhīmān na śocati / ātmano nityaikasvabhāvatvāvyabhicārāc chokakāraṇatvānupapatteḥ / tathā ca śrutyantaraṃ "tarati śokam ātmavit" (ChU 7,1.3) iti ///2,3.6 //

Shankara’s Commentary:
Com.—How is he to be known and what avails it to know him are explained. Of the senses, such as the ear, etc., separately originating from their causes, the akasa, etc., for perceiving their respective objects, knowing their distinctness, i.e., dissimilarity of their nature to the nature of the atman extremely pure, untainted, and all intelligence; and also the rising and setting, i.e., the creation and absorption of the senses, to depend on the waking and sleeping states and that the atman has neither beginning nor end, the intelligent man does not grieve. The eternally identical nature of the atman never changing, there can be no cause of grief. So also another sruti says ‘The knower of the atman crosses grief.’