Mundaka 6.03

नायमात्मा प्रवचनेन लभ्यो न मेधया न बहुना श्रुतेन। यमेवैष वृणुते तेन लभ्यः तस्येष आत्मा विवृणुते तनूं स्वाम् ॥३॥

nāyamātmā pravacanena labhyo na medhayā na bahunā śrutena। yamevaiṣa vṛṇute tena labhyaḥ tasyeṣa ātmā vivṛṇute tanūṃ svām ॥3॥

[न (na) - not; अयम् (ayam) - this; आत्मा (ātmā) - Ātmān; प्रवचनेन (pravacanena) - by discourse; लभ्यः (labhyaḥ) - is obtained; न (na) - not; मेधया (medhayā) - by intelligence; न (na) - not; बहुना (bahunā) - by much; श्रुतेन (śrutena) - by hearing; यम् (yam) - whom; एव (eva) - only; एषः (eṣaḥ) - this; वृणुते (vṛṇute) - chooses; तेन (tena) - by him; लभ्यः (labhyaḥ) - is obtained; तस्य (tasya) - his; एषः (eṣaḥ) - this; आत्मा (ātmā) - Ātmān; विवृणुते (vivṛṇute) - reveals; तनूं (tanūṃ) - body; स्वाम् (svām) - own;]

The Ātmān cannot be attained through discourse, intelligence, or extensive hearing. It is attained by the one whom the Ātmān chooses; to such a person, the Ātmān reveals its own body, i.e. its true nature.