Kaṭha Upaniṣad 90

90

naiṣā tarkeṇa matir āpaneyā proktānyenaiva sujñānāya preṣṭha /
yāṃ tvam āpaḥ satyadhṛtir batāsi tvādṛṅ no bhūyān naciketaḥ preṣṭā ///1,2.9 //

9. This idea cannot be reached by mere reasoning. This idea, Oh dearest, leads to sound knowledge, only if taught by another; thou hast reached it; Oh, thou art fixed in truth. May we find, Oh Nachiketas, a questioner like thee!