There the eye does not go, nor speech, nor mind. We do not know, we cannot understand, how one would teach it.
Kena Upanishad
केनोपनिषद्
मूल श्लोकः
न तत्र चक्षुर्गच्छति न वाग्गच्छति नो मनो। न विद्मो न विजानीमो यथैतदनुशिष्यात्॥
na tatra cakṣur gacchati na vāg gacchati no mano na vidmo na vijānīmo yathaitad anuśiṣyāt
KeU 1.3