St-Gregory-the-DialogistOn Luke 21:25-33.

When these things come to pass, look up, and lift up your heads, because your redemption is at hand (Luke 21:28).

It is as if the Truth openly warns His elect by saying: when the evils of this world mount up, when dread of the judgment is shown even by the trembling powers, lift up your heads, that is, be joyful in your hearts, because the world, of which you are not friends, is drawing to its end; the redemption you have been seeking is coming close.

[…] Whoever does not rejoice at the approaching end of the world, testifies that he is its friend, and by this he is revealed as an enemy of God.

But let this be far from the faithful, far from the hearts of those who believe through their faith that there is another life, and who love it in very deed.

Let them grieve over the ruin of the world who have planted the roots of their hearts deep in the love of it, who neither look for the life to come, nor are even aware that it is.

But we who have learned of the joys of our heavenly home must hasten to it as speedily as we may.  We should desire to go there with all haste, and to arrive by the shortest way.

And with what miseries does not the world urge us forward?  What sorrow, what misfortune is there, that does not press upon us?  What is this mortal life but a way?  And what folly would it be, let you carefully consider, to be weary with the fatigue of the way, and yet not eager to finish the journey!

That the world is to be trodden on, and despised, Our Redeemer then teaches us, by a timely similitude: Behold the fig tree and all the trees: when they now shoot forth their fruit, you know that summer is nigh. So you also when you shall see these things come to pass, know that the kingdom of God is at hand. 

This is as if he were openly to say: as from the fruit on the trees you know that summer is near, so from the ruin of the world you may know that the kingdom of God is likewise near.

From which it may be truly gathered that the fruit of the world is ruin. To this end it arises, that it may fall. To this end it germinates, that whatever it has brought forth from seed will be consumed in disaster.

But happily is the Kingdom of God compared to summer, because then the clouds of our sadness will pass away, and the days, of our life shall be resplendent in the glory of the eternal Sun.

Gregory the Great (c. 540-604): Homilies on the Gospel  (PL 76, 1077-1081; Homily 1), Translated by M.F. Toale, D.D. @ Lectionary Central.