Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 18
Sanskrit:
सीदच्चित्तं विलीयेत चेतसो ग्रहणेऽक्षमम् ।मनो नष्टं तमो ग्लानिस्तमस्तदुपधारय ॥ १८ ॥
ITRANS:
sīdac cittaṁ vilīyetacetaso grahaṇe ’kṣamammano naṣṭaṁ tamo glānistamas tad upadhāraya
Translation:
When one’s higher awareness fails and finally disappears and one is thus unable to concentrate his attention, his mind is ruined and manifests ignorance and depression. You should understand this situation to be the predominance of the mode of ignorance.