SB 12.4.30

na hi satyasya nānātvam
 avidvān yadi manyate
nānātvaṁ chidrayor yadvaj
 jyotiṣor vātayor iva
Word for word: 
na — there is no; hi — indeed; satyasya — of the Absolute Truth; nānātvam — duality; avidvān — a person not in true knowledge; yadi — if; manyate — he thinks; nānātvam — the duality; chidrayoḥ — of the two skies; yadvat — just as; jyotiṣoḥ — of the two celestial lights; vātayoḥ — of the two winds; iva — as.
Translation: 
There is no material duality in the Absolute Truth. The duality perceived by an ignorant person is like the difference between the sky contained in an empty pot and the sky outside the pot, or the difference between the reflection of the sun in water and the sun itself in the sky, or the difference between the vital air within one living body and that within another body.