Kaṭha Upaniṣad 253

253

na saṃdṛśe tiṣṭhati rūpam asya na cakṣuṣā paśyati kaścanainam /
hṛdā manīṣā manasābhikḷpto ya etad vidur amṛtās te bhavanti ///2,3.9 //

9. His form stands not within the fold of vision. None sees him with the eye. By the intellect controlling the mind, and by constant meditation is he revealed. Whoso knows that becomes immortal.