Here is the relevant essay The World's Last Night

The doctrine of the Second Coming is deeply uncongenial to the whole evolutionary or developmental character of modern thought. We have been taught to think of the world as something that grows slowly towards perfection, something that “Progresses” or “evolves.” Christian Apocalyptic offers us no such hope. It does not even foretell (which would be more tolerable to our habits of thought) a gradual decay. It foretells a sudden, violent end imposed from without; an extinguisher popped onto the candle, a brick flung at the gramophone, a curtain rung down on the play — “Halt!” To this deep-seated objection I can only reply that, in my opinion, the modern conception of Progress or Evolution (as popularly imagined) is simply a myth, supported by no evidence whatever. . . .

The idea that the myth (so potent in all modern thought) is a result of Darwin’s biology would thus seem to be unhistorical. On the contrary, the attraction of Darwinism was that it gave to a pre-existing myth the scientific reassurances it required. If no evidence for evolution had been forthcoming, it would have been necessary to invent it. The real sources of the myth are partly political. It projects onto the cosmic screen feelings engendered by the Revolutionary period. . . .

The doctrine of the Second Coming teaches us that we do not and cannot know when the world drama will end. The curtain may be rung down at any moment: say, before you have finished reading this paragraph. This seems to some people intolerably frustrating. So many things would be interrupted. Perhaps you were going to get married next month, perhaps you were going to get a raise next week: you may be on the verge of a great scientific discovery; you may be maturing great social and political reforms. Surely no good and wise God would be so very unreasonable as to cut all this short? Not now, of all moments! . . . The doctrine of the Second Coming has failed, so far as we are concerned, if it does not make us realize that at every moment of every year in our lives Donne’s question “What if this present were the world’s last night?” is equally relevant. Sometimes this question has been pressed upon our minds with the purpose of exciting fear. I do not think that is its right use. . . .

What is important is not that we should always fear (or hope) about the End but that we should always remember, always take it into account.

An analogy may here help. A man of seventy need not be always feeling (much less talking) about his approaching death: but a wise man of seventy should always take it into account. He would be foolish to embark on schemes which presuppose twenty more years of life: he would be criminally foolish not to make—indeed, not to have made long since—his will. Now, what death is to each man, the Second Coming is to the whole human race. We all believe, I suppose, that a man should “sit loose” to his own individual life, should remember how short, precarious, temporary, and provisional a thing it is; should never give all his heart to anything which will end when his life ends.

What modern Christians find it harder to remember is that the whole life of humanity in this world is also precarious, temporary, provisional. . . . Frantic administration of panaceas to the world is certainly discouraged by the reflection that “this present” might be “the world’s last night”; sober work for the future, within the limits of ordinary morality and prudence, is not. For what comes is Judgment: happy are those whom it finds labouring in their vocations, whether they were merely going out to feed the pigs or laying good plans to deliver humanity a hundred years hence from some great evil. The curtain has indeed now fallen. Those pigs will never in fact be fed, the great campaign against White Slavery or Governmental Tyranny will never in fact proceed to victory. No matter; you were at your post when the Inspection came. . . .

I do not find that pictures of physical catastrophe—that sign in the clouds, those heavens rolled up like a scroll—help one so much as the naked idea of Judgment. We cannot always be excited. We can, perhaps, train ourselves to ask more and more often how the thing which we are saying or doing (or failing to do) at each moment will look when the irresistible light streams in upon it; that light which is so different from the light of this world—and yet, even now, we know just enough of it to take it into account. Women sometimes have the problem of trying to judge by artificial light how a dress will look by daylight. That is very like the problem of all of us: to dress our souls not for the electric lights of the present world but for the daylight of the next. The good dress is the one that will face that light. For that light will last longer.

Source:“The World’s Last Night” (orig. 1952), in The World’s Last Night and Other Essays