No one living in this life can see [God] as he is. Many have seen, but they saw what his will chose, not what his nature formed, and this is what John said, if he is rightly understood: “Dearly beloved, we are the sons of God, and it has not yet appeared what we shall be. We know that when he shall appear, we shall be like to him, because we shall see him as he is”; not as men saw him when he willed under the appearance that he willed; not in his nature under which he lies hidden within himself even when he is seen, but as he is. This is what was asked of him by the one who spoke to him face to face, when he said to him, “Show me yourself,” but no one can at any time experience the fullness of God through the eyes of the body any more than by the mind itself.

–Letter 147.8-9