Origen

“ God, moreover, is in our judgment invisible, because He is not a body, while He can be seen by those who see with the heart, that is, the understanding; not indeed with any kind of heart, but with one which is pure. ”

“ Celsus, however, asserts that the answer which we give is based upon a probable conjecture, [1] admitting that he describes our answer in the following terms: “Since God is great and difficult to see, [2] He put His own Spirit into a body that resembled ours, and sent it down to us, that we might be enabled to hear Him and become acquainted with Him.” But the God and Father of all things is not the only being that is great in our judgment ”