Joel 2:10

What, then, is the vanity, and what the lie? The holy apostle of the Lord, reprehending the Greeks, will show thee: "Because that, when they knew God, they glorified Him not as God, neither were thankful; but became vain in their imaginations, and changed the glory of God into the likeness of corruptible man, and worshipped and served the creature more than the Creator." And verily this is the God who "in the beginning made the heaven and the earth." But you do not know God, and worship the heaven, and how shall you escape the guilt of impiety? Hear again the prophet speaking: "The sun, shall suffer eclipse, and the heaven be darkened; but the Almighty shall shine for ever: while the powers of the heavens shall be shaken, and the heavens stretched out and drawn together shall be rolled as a parchment-skin (for these are the prophetic expressions), and the earth shall flee away from before the face of the Lord."

Immediately after the tribulation of those days the sun shall be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be moved. And then shall appear the sign of the Son of man in heaven, and then shall all the tribes of the earth mourn (24, 29—30ᵃ). Since we consider that greater themes here come under discussion than lie within the grasp of human understanding — even of those who have advanced in wisdom far beyond others — let us come and examine the passage: first inquiring into those things which can readily be admitted for an exposition of the Gospel text, as though the Lord Himself were prophesying in it; and afterward we shall look for what the truth of these words may be according to those who judge that there is something deeper and more subtle in the words, keeping to the sequence of the moral traditions in these matters as well, in the same manner as above. Someone, then, will say: just as when great fires begin to be kindled a darkness seems to be raised up out of the abundant smoke, so at the consummation of the world, by the fire which is to be set alight, even the "great lights" shall be darkened, so that, the sun being darkened, and in consequence of the darkening of the sun, the moon too, hindered by the sun from receiving light, is not permitted even to give its own light. And thus of necessity a great darkness must first take hold of the nature of the world. And so, when the light of the stars has thus withered away, the remaining body of them, having become grosser, since it cannot be borne aloft as at first when it was lifted up carried by the light itself, will fall from heaven. And when these things happen, it follows that the rational powers of the heavens, suffering amazement, undergo a certain commotion and are troubled, being, that is, removed from their former functions. So he who understands these things to be thus will add that the sign of the Son of man, in whom "the things that were in the heavens and the things that were on earth" were made heavenly, shall then appear: namely, the power which the Son of man wrought when He was hung upon the tree; and in heaven above all shall His sign shine forth. And men out of all the tribes, who formerly did not believe in the Christianity that was proclaimed but even spoke evil of it, then, recognizing it through that…