मनो ब्रह्मेति व्यजानात् ।मनसो ह्येव खल्विमानि भूतानि जायन्ते ।मनसा जातानि जीवन्ति ।मनः प्रयन्त्यभिसंविशन्तीति ।तद्विज्ञाय ।पुनरेव वरुणं पितरमुपससार ।अधीहि भगवो ब्रह्मेति ।तँ होवाच ।तपसा ब्रह्म विजिज्ञासस्व ।तपो ब्रह्मेति ।स तपोऽतप्यत ।स तपस्तप्त्वा ॥ १ ॥
In plain words
he knew that mind is Brahman; for from mind indeed are these beings born, by mind, being born, they live, and into mind, departing, they enter. Having known that, he came again to his father Varuṇa and said, "Sir, teach me Brahman." He said to him, "Seek to know Brahman by austerity; austerity is Brahman." So he performed austerity; and having performed austerity,