Patristic Wisdom: Looking to the First Sunday in Advent

But in those days, after that tribulation, the sun will be darkened, and the moon will not give its light; the stars of heaven will fall, and the powers in the heavens will be shaken. Then they will see the Son of Man coming in the clouds with great power and glory. And then He will send His angels, and gather together His elect from the four winds, from the farthest part of earth to the farthest part of heaven.

Now learn this parable from the fig tree: When its branch has already become tender, and puts forth leaves, you know that summer is near. So you also, when you see these things happening, know that it is near—at the doors! Assuredly, I say to you, this generation will by no means pass away till all these things take place. Heaven and earth will pass away, but My words will by no means pass away. (Mark 13:24-31)

If you examine the whole passage of this Gospel Scripture, from the inquiry of the disciples down to the parable of the fig-tree you will find that it makes sense at every point in connection with the coming of the Son of man, so that it consistently ascribes to Him both the sorrows and the joys, and the catastrophes and the promises; nor can you separate them from Him in either respect. For as much, then, as there is but one Son of man whose advent is placed between the two issues of catastrophe and promise, it must necessarily follow that to that one Son of man belong both the judgments upon the nations and the prayers of the saints. He who thus comes in midway so as to be common to both issues, will terminate one of them by inflicting judgment on the nations at His coming; and will at the same time commence the other by fulfilling the longings of His saints.… Reflect, in short, on the picture presented in the parable: “Behold the fig-tree, and all the trees; when they produce their fruit, men know that summer is at hand. So likewise when you see these things come to pass, know that the kingdom of God is very near.” Now, if the fructification of the common trees is an antecedent sign of the approach of summer, so in like manner do the great conflicts of the world indicate the arrival of that kingdom which they precede. But every sign is His, to whom belong the thing of which it is the sign; and to everything is appointed its sign by Him to whom the thing belongs. If, therefore, these tribulations are the signs of the kingdom, just as the maturity of the trees is of the summer, it follows that the kingdom is the Creator’s to whom are ascribed the tribulations which are the signs of the kingdom. Since the beneficent Deity had premised that these things must necessarily come to pass, although so terrible and dreadful, as they had been predicted by the law and the prophets, therefore He did not destroy the law and the prophets, when He affirmed that what had been foretold must be certainly fulfilled. He further declares, “that heaven and earth shall not pass away till all things be fulfilled.”

Tertullian, Against Marcion IV.39