Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 4

Sanskrit:

सान्द्रनीलाम्बुदैर्व्योम सविद्युत्स्तनयित्नुभि: ।अस्पष्टज्योतिराच्छन्नं ब्रह्मेव सगुणं बभौ ॥ ४ ॥

ITRANS:

sāndra-nīlāmbudair vyomasa-vidyut-stanayitnubhiḥaspaṣṭa-jyotir ācchannaṁbrahmeva sa-guṇaṁ babhau

Translation:

The sky was then covered by dense blue clouds accompanied by lightning and thunder. Thus the sky and its natural illumination were covered in the same way that the spirit soul is covered by the three modes of material nature.

Purport:

Lightning is compared to the mode of goodness, thunder to the mode of passion, and clouds to the mode of ignorance. Thus the cloudy sky at the onset of the rainy season is analogous to the pure spirit soul when he becomes disturbed by the modes of nature, for at that time he is covered and his original brilliant nature is only dimly reflected through the haze of the material qualities.