Bhagavad Gita, Chapter 11, Verse 19

I see You without beginning, middle or end, infinite in power, of manifold arms; the sun and the moon Your eyes, the burning fire Your mouth; heating the whole universe with Your radiance.

Familiar things, the sun, the moon, fire, are described here as small parts of something far larger.

Comparing sun and moon to eyes and fire to a mouth gives real, physical shape to an otherwise unimaginable scale. Even the most enormous things Arjun already knew are folded into this one form.