Bhagavad Gita Chapter 11, Verse 12

दिवि सूर्यसहस्रस्य भवेद्युगपदुत्थिता | यदि भाः सदृशी सा स्याद्भासस्तस्य महात्मनः ||

divi sūrya-sahasrasya bhaved yugapad utthitā yadi bhāḥ sadṛśī sā syād bhāsas tasya mahātmanaḥ

If thousands of suns were to rise simultaneously in the sky, their radiance would be similar to the radiance of that great soul.

Arjuna uses a powerful comparison to describe the cosmic form's brilliance. 'Divi sūrya-sahasrasya bhaved yugapad utthitā'—if thousands of suns (sūrya-sahasrasya) were to rise simultaneously (yugapad utthitā) in the sky (divi). 'Yadi bhāḥ sadṛśī sā syāt'—if that radiance (bhāḥ) would be similar (sadṛśī). 'Bhāsas tasya mahātmanaḥ'—the radiance (bhāsaḥ) of that great soul (mahātmanaḥ). Arjuna is trying to convey the unimaginable brilliance of the cosmic form—it's as bright as thousands of suns rising at once. This comparison helps us understand the overwhelming radiance of the universal form. The cosmic form's effulgence is beyond ordinary comprehension—it requires comparison to the impossible to even begin to describe it.