Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 48
Sanskrit:
यं वै न वेद वितथाक्षपथैर्भ्रमद्धी:सन्तं स्वकेष्वसुषु हृद्यपि दृक्पथेषु ।तन्माययावृतमति: स उ एव साक्षा-दाद्यस्तवाखिलगुरोरुपसाद्य वेदम् ॥ ४८ ॥
ITRANS:
yaṁ vai na veda vitathākṣa-pathair bhramad-dhīḥsantaṁ svakeṣv asuṣu hṛdy api dṛk-patheṣutan-māyayāvṛta-matiḥ sa u eva sākṣādādyas tavākhila-guror upasādya vedam
Translation:
A materialist, his intelligence perverted by the action of his deceptive senses, cannot recognize You at all, although You are always present within his own senses and heart and also among the objects of his perception. Yet even though one’s understanding has been covered by Your illusory potency, if one obtains Vedic knowledge from You, the supreme spiritual master of all, he can directly understand You.