Exodus 33:21

9. And the Word spake to Moses, appearing before him, “just as any one might speak to his friend.” But Moses desired to see Him openly who was speaking with him, and was thus addressed: “Stand in the deep place of the rock, and with My hand I will cover thee. But when My splendour shall pass by, then thou shalt see My back parts, but My face thou shalt not see: for no man sees My face, and shall live.” Two facts are thus signified: that it is impossible for man to see God; and that, through the wisdom of God, man shall see Him in the last times, in the depth of a rock, that is, in His coming as a man. And for this reason did He [the Lord] confer with him face to face on the top of a mountain, Elias being also present, as the Gospel relates, He thus making good in the end the ancient promise.

You ought to be very much ashamed of yourself on this account too, for permitting him to appear on the retired mountain in the company of Moses and Elias, whom he had come to destroy. This, to be sure, was what he wished to be understood as the meaning of that voice from heaven: “This is my beloved Son, hear Him”, Him , that is, not Moses or Elias any longer. The voice alone, therefore, was enough, without the display of Moses and Elias; for, by expressly mentioning whom they were to hear, he must have forbidden all others from being heard. …

28. Add, too, that which the Lord afterward said to Moses, “Thou canst not see my face: for there shall no man see my face, and live. And the Lord said, Behold, there is a place by me, and thou shall stand upon a rock: and it shall come to pass, while my glory passeth by, that I will put thee into a watch-tower of the rock, and will cover thee with my hand while I pass by: and I will take away my hand, and thou shalt see my back parts; but my face shall not be seen.”

Jacob in his flight from his brother left behind in his father’s house great riches and made his way with nothing into Mesopotamia. Moreover, to prove to us his powers of endurance, he took a stone for his pillow. Yet as he lay there he beheld a ladder set up on the earth reaching to heaven and behold the Lord stood above it, and the angels ascended and descended on it; the lesson being thus taught that the sinner must not despair of salvation nor the righteous man rest secure in his virtue. To pass over much of the story (for there is no time to explain all the points in the narrative) after twenty years he who before had passed over Jordan with his staff returned into his native land with three droves of cattle, rich in flocks and herds and richer still in children. …

62. It is an extraordinary statement, but it is none the less true, that the Spirit is frequently spoken of as the place of them that are being sanctified, and it will become evident that even by this figure the Spirit, so far from being degraded, is rather glorified. For words applicable to the body are, for the sake of clearness, frequently transferred in scripture to spiritual conceptions. Accordingly we find the Psalmist, even in reference to God, saying “Be Thou to me a champion God and a strong place to save me” and concerning the Spirit “behold there is place by me, and stand upon a rock.” Plainly meaning the place or contemplation in the Spirit wherein, after Moses had entered thither, he was able to see God intelligibly manifested to him. …