The Mukhya Upaniṣads

Aitareya · Adhyāya 1 · Khaṇḍa 3 · The Search for Food, and the Discovery of Who Asks

Passage 2

सोऽपोऽभ्यतपत्ताभ्योऽभितप्ताभ्यो मूर्तिरजायत ।या वै सा मूर्तिरजायतान्नं वै तत् ॥ २ ॥

In plain words

He heated those waters; from them, heated, a form (mūrti) was born. That form which was born — that indeed is food.