The Mukhya Upaniṣads

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

Passage 8

तन्मनसाजिघृक्षत्तन्नाशक्नोन्मनसा ग्रहीतुं स यद्धैनन्मनसाग्रहैष्यद्ध्यात्वा हैवान्नमत्रप्स्यत् ॥८॥

In plain words

He tried to seize it with the mind; he was unable to grasp it with the mind. Had he grasped it with the mind, i.e. merely by thinking of it, then merely by with the mind, i.e. merely by thinking of it, one would have been satisfied by food.