From chapter IX “Authority and the Adventurer” in Orthodoxy by G.K. Chesterton:
And in history I found that Christianity, so far from belonging to the dark ages, was the one path across the dark ages that was not dark. It was a shining bridge connecting two shining civilisations. If any one says that the faith arose in ignorance and savagery the answer is simple: it didn’t. It arose in the Mediterranean civilisation in the full summer of the Roman Empire. The world was swarming with sceptics, and pantheism was as plain as the sun, when Constantine nailed the cross to the mast. It is perfectly true that afterwards the ship sank; but it is far more extraordinary that the ship came up again: repainted and glittering, with the cross still at the top. This is the amazing thing the religion did: it turned a sunken ship into a submarine. The ark lived under the load of waters; after being buried under the débris of dynasties and clans, we arose and remembered Rome. If our faith had been a mere fad of the fading empire, fad would have followed fad in the twilight, and if the civilisation ever re-emerged (and many such have never re-emerged) it would have been under some new barbaric flag. But the Christian Church was the last life of the old society and was also the first life of the new. She took the people who were forgetting how to make an arch and she taught them to invent the Gothic arch. In a word, the most absurd thing that could be said of the Church is the thing we have all heard said of it. How can we say that the Church wishes to bring us back into the Dark Ages? The Church was the only thing that ever brought us out of them.
…The highest gratitude and respect are due to the great human civilisations such as the old Egyptian or the existing Chinese. Nevertheless it is no injustice for them to say that only modern Europe has exhibited incessantly a power of self-renewal recurring often at the shortest intervals and descending to the smallest facts of building or costume. All other societies die finally and with dignity. We die daily. We are always being born again with almost indecent obstetrics. It is hardly an exaggeration to say that there is in historic Christendom a sort of unnatural life: it could be explained as a supernatural life. It could be explained as an awful galvanic life working in what would have been a corpse. For our civilisation ought to have died, by all parallels, by all sociological probability, in the Ragnorak of the end of Rome. That is the weird inspiration of our estate: you and I have no business to be here at all. We are all revenants; all living Christians are dead pagans walking about. Just as Europe was about to be gathered in silence to Assyria and Babylon, something entered into its body. And Europe has had a strange life—it is not too much to say that it has had the jumps—ever since.