He that believeth on Me, believeth not on Me, but on Him that sent Me: as if He said, He that taketh water from a stream, taketh the water not of the stream, but of the fountain. Then to shew that it is not possible to believe on the Father, if we do not believe on Him, He says, He that seeth Me, seeth Him that sent Me. What then? Is God a body? By no means; seeing here is the mind’s vision. What follows still further shews His union with the Father. I am come a light into the world. This is what the Father is called in many places. He calls Himself the light, because he delivers from error, and disperses the darkness of the understanding; that whosoever believeth in Me should not abide in darkness.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. lxix. 1