Mark 13:24

And just as when the moon is in opposition to the sun, it disappears through the regular flow of the menstrual cycle or through the alignment of the earth, so too the holy Church, when the vices of the flesh oppose the heavenly light, cannot receive the divine radiance of Christ's rays. For in persecutions, the love of this life often excludes the light of God alone.

"And I saw another angel ascending from the east, having the seal of the living God" He speaks of Elias the prophet, who is the precursor of the times of Antichrist, for the restoration and establishment of the churches from the great and intolerable persecution. We read that these things are predicted in the opening of the Old and New Testament; for He says by Malachi: "Lo, I will send to you Elias the Tishbite, to turn the hearts of the fathers to the children, according to the time of calling, to recall the Jews to the faith of the people that succeed them." And to that end He shows, as we have said, that the number of those that shall believe, of the Jews and of the nations, is a great multitude which no man was able to number. Moreover, we read in the Gospel that the prayers of the Church are sent from heaven by an angel, and that they are received against wrath, and that the kingdom of Antichrist is cast out and extinguished by holy angels; for He says: "Pray that ye enter not into temptation: for there shall be a great affliction, such as has not been from the beginning of the world; and except the Lord had shortened those days, no flesh should be saved." Therefore He shall send these seven great archangels to smite the kingdom of Antichrist; for He Himself also thus said: "Then the Son of man shall send His messengers; and they shall gather together His elect from the four corners of the wind, from the one end of heaven even to the other end thereof." For, moreover, He previously says by the prophet: "Then shall there be peace for our land, when there shall arise in it seven shepherds and eight attacks of men; and they shall encircle Assur," that is, Antichrist, "in the trench of Nimrod," that is, in the nation of the devil, by the spirit of the Church. Similarly when the keepers of the house shall be moved. […]

And upon the coming of the Antichrist, all creation will be changed: the sun and moon will grow dark from the superabundance of Christ's light.

But after the coming of Antichrist, the frame of the world shall be altered and changed, for the stars shall be obscured on account of the abundance of the brightness of Christ. Wherefore it goes on: But in those days, after that tribulation, the sun shall be darkened, and the moon shall not give her light; and the stars of heaven shall fall. That is, the Angelic virtues shall be astonished, seeing that such great things are done, and that their fellow-servants are judged.

Our Lord and Redeemer, most beloved brethren, desiring to find us prepared, announces what evils will follow upon the aging world, so that He might restrain us from love of it. He makes known what great calamities will precede its approaching end, so that if we are unwilling to fear God in times of peace, we may at least fear His judgment drawing near, worn down by these afflictions. Of all these things, we certainly see some already accomplished, and we dread others as soon to come. For we see nation rising against nation and their pressure bearing down upon the lands more in our own times than we read of in books. How often we have heard from other parts of the world that earthquakes have destroyed countless cities, you well know. We suffer pestilences without ceasing. Signs in the sun, and moon, and stars we do not yet see openly, but that these too are not far off we gather from the very changes in the atmosphere. Indeed, before Italy was handed over to be struck by the barbarian sword, we saw fiery battle lines in the sky, flashing with that very blood of the human race which was afterward shed. But since many things foretold have already been fulfilled, there is no doubt that the few which remain will also follow, for the fulfillment of past events is the certainty of things to come.