Mandukya Karika, verse 2.6

Text

आदावन्ते च यन्नास्ति वर्तमानेऽपि तत्तथा |
वितथैः सदृशाः सन्तोऽवितथा इव लक्षिताः || 6 ||

ādāvante ca yannāsti vartamāne'pi tattathā |
vitathaiḥ sadṛśāḥ santo'vitathā iva lakṣitāḥ || 6 ||

6. That which is non-existent at the beginning and in the end, is necessarily so (non-existent) in the middle. The objects are like the illusions we see, still they are regarded as if real.

Shankara Bhashya (commentary)

The objects perceived to exist in the waking state are unreal for this reason also,1 that they do not really exist either at the beginning or at the end. Such objects (of experience) as mirage, etc., do not really exist either at the beginning or at the end. Therefore they do not (really) exist in the middle either. This is the decided2 opinion of the world. The several objects perceived to exist really in the waking state are also of the same3 nature. Though they (the objects of experience) are of the same nature as illusory objects, such as mirage, etc., on account of their non-existence at the beginning and at the end, still they are regarded as real by the ignorant, that is, the persons that do not know Ātman.