The Mukhya Upaniṣads

Aitareya · Adhyāya 3 · Khaṇḍa 1 · Who Is This Self? -- Consciousness Is Brahman

Passage 1

कोऽयमात्मेति वयमुपासमहे कतरः स आत्मा येन वा पश्यति येन वा शृणोति येन वा गन्धानाजिघ्रति येन वा वाचं व्याकरोति येन वा स्वादु चास्वादु च विजानाति ॥ १ ॥

In plain words

'Who is this Self?' -- thus do we meditate. Which one is that Self -- is it that by which one sees, or that by which one hears, or that by which one smells odors, or that by which one articulates speech, or that by which one distinguishes the sweet and the unsweet?