Mandukya Karika, verse 2.3

Sanskrit text, IAST transliteration and English translation

अभावश्च रथादीनां श्रूयते न्यायपूर्वकम् ।
वैतथ्यं तेन वै प्राप्तं स्वप्न आहुः प्रकाशितम् ॥ ३ ॥

abhāvaśca rathādīnāṃ śrūyate nyāyapūrvakam |
vaitathyaṃ tena vai prāptaṃ svapna āhuḥ prakāśitam || 3 ||

3. Following reason, (as indicatea above) Śruti declares the non-existence of the chariots, etc. (perceived in dream). Therefore it is said (by the wise) that Śruti itself declares the illusoriness (of the dream-experiences), established (by reason).

Shankara Bhashya (commentary)

For this reason also the objects perceived to exist in dream are illusory. For, the absence of the chariots, etc. (perceived in dream) is stated by Śruti, in such passages as “There¹ exists neither chariot, etc.” its assertion being based on reason.² In the opinion of the wise, i.e., the knowers of Brahman, the illusoriness (of the dream objects) has been established on the ground of their being perceived within the contracted space in the body. The Śruīi only reiterates it in order to establish the self-luminosity³ (of Ātman) in dream.

Anandagiri Tika (glossary)

¹ There, etc.—Comp. Bṛhadāraṇyaka Upaniṣad, 4. 3. 10.

² Reason— The reason, as adduced in the previous Kārikā, is the absence of the appropriate time and space for the real existence of such dream objects.

³ Self-luminosity—Comp. Bṛhadāraṇyaka Upaniṣad, 4. 3. 14. Mere examination of the waking experiences cannot prove that Ātman is self-luminous. For it may be contended that various activities, associated with the waking state, are due to the functioning of the sense organs under the influence, as the Śruti says, of the various luminous deities as the sun, the fire, etc. But in sleep various activities are experienced by the dreamer and these activities, in the absence of the functionings of the sense-organs, are due to the self-luminosity of Ātman.