Fascinating and mysterious considerations, from St. Augustine:
By all means, I think these [prophetic developments] are better understood with regard to the Church, lest the Lord Jesus, with His second coming drawing near, seem to have foretold as being of great consequence [developments] that had been accustomed to happen to this world even before His first coming, and [lest] we be laughed at by those who have read in the history of nations more and much greater things than the ones at which we tremble as the final and most important of all. For the Church is the sun and the moon and the stars, to which it was said, “fair as the moon, bright as the sun” (Canticle of Canticles 6:9). In this world our Joseph [=son of Jacob and Rachel] is worshipped [=venerated] by the [moon], as though in Egypt [when he had been] lifted up on high from the lowliest [condition]. For the Joseph’s mother, who died before Jacob had come to his son, was certainly unable to worship him, in order that the truth of the prophetic dream (Genesis 37:9), to be fulfilled with Christ the Lord, might be preserved.
For when “the sun shall be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of heaven shall be moved,” just as this passage was recorded by the other two Evangelists (Matthew 24:29, Mark 13:24), the Church will not be perceptible at that time, with the ungodly persecutors raging beyond measure and with all fear laid aside as though the world’s good fortune were smiling approvingly, while they say, “Peace and security” [1 Thessalonians 5:3]. Then the stars shall fall from the heaven, and the powers of heaven shall be moved, because many who seemed to shine brightly with grace will yield to the persecutors and will fall, and some of the most valiant faithful will be confounded. However, for this reason, according to Matthew and Mark it is said that this will take place after the tribulation of those days, not because these things will happen after that entire persecution has been brought to an end, but because the tribulation will come before, in order that certain people’s defection [from the faith] may follow. And because it will come to pass in such a way through all those days, therefore after the tribulation of those days, but all the same it will nonetheless come to pass in the same days.
(St. Augustine, Epistola CXCIX, par. 39; in Collectio Selecta Ss. Ecclesiae Patrum, vol. CXLVIII (Paris: Parent-Desbarres, 1835), pp. 127-128; underlining added. Professional translation commissioned by Novus Ordo Watch.)
Also Augustine says: “Unbelievers think that the Christian religion will last for a certain period in the world and will then disappear. But it will remain as long as the sun – as long as the sun rises and sets: that is, as long as the ages of time shall roll, the Church of God – the true body of Christ on earth – will not disappear” (In Psalm. lxx., n. 8). And in another place: “The Church will totter if its foundation shakes; but how can Christ be moved?…Christ remaining immovable, it (the Church) shall never be shaken. Where are they that say that the Church has disappeared from the world, when it cannot even be shaken?” (Enarratio in Psalm. ciii., sermo ii., n. 5).
(Pope Leo XIII, Encyclical Satis Cognitum, n. 3)