Mandukya Karika, verse 2.15


अव्यक्ता एव येऽन्तस्तु स्फुटा एव च ये बहिः ।
कल्पिता एव ते सर्वे विशेषस्त्विन्द्रियान्तरे ॥ १५ ॥

avyaktā eva ye'ntastu sphuṭā eva ca ye bahiḥ |
kalpitā eva te sarve viśeṣastvindriyāntare || 15 ||

15. Those that exist within the mind (as mere subjective imaginations) and are known as the unmanifested as well as those that exist without in a manifested form (as perceived objects),—all are mere imaginations, the difference lying only in the sense-organs (by means of which the latter are cognized).

Shankara Bhashya (commentary)

Though1 the objects perceived within, as mere mental impressions, are unmanifested, and though2 the objects perceived outside through the sense-organs such as eyes, etc., are known as manifested (gross entities), yet the distinction3 is not due to anything substantial in the nature of the (two kinds of) objects. For, such distinction is seen in dreams as well. What is, then, the cause of this distinction? It4 is only due to the difference in the use of sense-organs (by means of which these objects are perceived). Hence, it is established that the objects perceived in the waking state are as much imagination of the mind as those seen in the dream.