The Mukhya Upaniṣads

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

Passage 5

तच्चक्षुषाजिघृक्षत्तन्नाशक्नोच्चक्षुषा ग्रहीतुं स यद्धैनच्चक्षुषाग्रहैष्यद् दृष्ट्वा हैवान्नमत्रप्स्यत् ॥ ५ ॥

In plain words

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