Maitri (Maitrāyaṇīya) Upaniṣad 6.11

6.11

paraṃ vā etadātmano rūpaṃ yadannamannamayo hyayaṃ prāṇo'tha na yadyaśnātyamantā'śrotā'spraṣṭā'draṣṭā'vaktā'ghrātārasayitā bhavati prāṇāṃścotsṛjatīti evaṃ hyāhātha yadi khalvaśnāti prāṇasamṛddho bhūtvā mantā bhavati śrotā bhavati spraṣṭā bhavati vaktā bhavati rasayitā bhavati ghrātā bhavati draṣṭā bhavatīti evaṃ hyāha annādvai prajāḥ prajāyante yāḥ kaścitpṛthivīśṛtāḥ | ato'nnenaiva jīvanti athaitadapi yanti antataḥ ||

11. This, verily, is the highest form of the Soul (Ātman), namely food; for truly, this life (prāṇa, breath) consists of food. For thus has it been said : ‘If one does not eat, he becomes a non-thinker, a non-hearer, a non-toucher, a non-seer, a non-speaker, a non-smeller, a non-taster, and he lets go his vital breaths.’ [And furthermore:] ‘If, indeed, one eats, he becomes well supplied with life; he becomes a thinker; he becomes a hearer; he becomes a toucher; he becomes a speaker; he becomes a taster; he becomes a smeller; he becomes a seer.’ For thus has it been said :—

From food, verily, creatures are produced,
Whatsoever [creatures] dwell on the earth.
Moreover by food, in truth, they live.
Moreover into it also they finally pass.