Brihadaranyaka Upanishad 6.1.11

6.1.11

mano hoccakrāma tatsaṃvatsaraṃ proṣyāgatyovāca kathamaśakata madṛte jīvitumiti te hocuryathā mugdhā avidvām̐so manasā prāṇantaḥ prāṇena vadanto vācā paśyantaścakṣuṣā śṛṇvantaḥ śrotreṇa prajāyamānā retasaivamajīviṣmeti praviveśa ha manaḥ

The mind went out. After staying a whole year out it came back and said, ‘How did you manage to live without me?’ They said, ‘We lived just as idiots do, without knowing through the mind, but living through the vital force, speaking through the organ of speech, seeing through the eye, hearing through the ear and having children through the organ of generation.’ So the mind entered.