Kaṭha Upaniṣad 3.13

3.13

prājñaḥ ātmā jijñāsuḥ puruṣaḥ vāk vāgādisarvendriyagaṇaṃ manasi sarvendriyāniyāmake saṃkalpavikalpaparūpe yacchet nirundhyāt manovyāpārātiriktendriyavyāpārābhāvaṃ kuryāditi yāvat | tat manaḥ jñāna ātmani niścalarūpāyāṃ vyaṣṭibuddhau yacchet nirundhyāt | vyaṣṭibuddhivyāpārātiriktamanovyāpārābhāvaṃ kuryāt | jñānaṃ vyaṣṭibuddhitattvaṃ ātmani mahati vyaṣṭibuddhīnāmātmabhūte mahattattve samaṣṭibuddhirūpe niyacchet vilāpayet | samaṣṭibuddhivyatiriktavyaṣṭibuddhīnīstīti cintayet | tat samaṣṭibuddhitattvaṃ śānte nirvikāre ātmani pratyagātmani sarvakaraṇavyāpārasākṣiṇi yacchet vilāpayet ātmātiriktasamaṣṭibuddhyacabhāvaṃ cintayedityarthaḥ |
evaṃ yogābhyāsena cittasyaikāgratāṃ sampādya yatrātmani samāhitaṃ stasyātmano jñāne prayatitavyamiti mātṛvaddhitaiṣiṇī śrutirāha--