I thought of this quote from Gregory of Nazianzus as I was reading the first chapter of the 1541 French edition of Calvin’s Institutes (more on that at a later date).
What is this that has happened to me, O friends, and initiates, and fellow lovers of the truth? I was running to lay hold on God, and thus I went up into the Mount, and drew aside the curtain of the cloud, and entered away from matter and material things, and as far as I could I withdrew within myself. And then when I looked up, I scarce saw the back parts of God; although I was sheltered by the rock, the Word that was made flesh for us. And when I looked a little closer, I saw, not the first and unmingled Nature, known to itself—to the Trinity, I mean; not that which abides within the first veil, and is hidden by the cherubim; but only that nature, which at last even reaches to us. And that is, as far as I can learn, the majesty, or as holy David calls it, the glory which is manifested among the creatures, which it has produced and governs. For these are the back parts of God, which He leaves behind Him, as tokens of himself like the shadows and reflection of the sun in the water, which show the sun to our weak eyes, because we cannot look at the sun himself, for by his unmixed light he is too strong for our power of perception. In this way then you shall discourse of God; even were you a Moses and a god to Pharaoh; even were you caught up like Paul to the third heaven, and had heard unspeakable words; even were you raised above them both, and exalted to angelic or archangelic place and dignity. For though a thing be all heavenly, or above heaven, and far higher in nature and nearer to God than we, yet it is farther distant from God, and from the complete comprehension of his nature, than it is lifted above our complex and lowly and earthward-sinking composition.
“The Second Theological Oration,” in Christology of the Later Fathers, ed by Edward R. Hardy (Westminster: WJK, 1954), 137-8.
Calvin also makes use of the sun metaphor in discussing our ability to know God, though it is so prevalent that it really isn’t surprising. What I find different is that for Calvin man’s inability to know God is due to sin, whereas for Gregory it seems to be an ontological problem, viz., God’s “nature” is such that cannot be known by humankind.