All the great groups that stood about the Cross represent in one way or another the great historical truth of the time; that the world could not save itself. Man could do no more. Rome and Jerusalem and Athens and everything else were going down like a sea turned into a slow cataract. Externally indeed the ancient world was still at its strongest; it is always at that moment that the inmost weakness begins. But in order to understand that weakness we must repeat what has been said more than once; that it was not the weakness of a thing originally weak. It was emphatically the strength of the world that was turned to weakness and the wisdom of the world that was turned to folly.In this story of Good Friday it is the best things in the world that are at their worst. That is what really shows us the world at its worst. It was, for instance, the priests of a true monotheism and the soldiers of an international civilisation. Rome, the legend, founded upon fallen Troy and triumphant over fallen Carthage, had stood for a heroism which was the nearest that any pagan ever came to chivalry. Rome had defended the household gods and the human decencies against the ogres of Africa and the hermaphrodite monstrosities of Greece. But in the lightning flash of this incident, we see great Rome, the imperial republic, going downward under her Lucretian doom. Scepticism has eaten away even the confident sanity of the conquerors of the world. He who is enthroned to say what is justice can only ask:‘What is truth?’ So in that drama which decided the whole fate of antiquity, one of the central figures is fixed in what seems the reverse of his true role. Rome was almost another name for responsibility. Yet he stands for ever as a sort of rocking statue of the irresponsible. Man could do no more. Even the practical had become the impracticable. Standing between the pillars of his own judgement-seat, a Roman had washed his hands of the world.
What happened? It took Gibbon six volumes to describe the decline and fall of the Roman Empire, so I shan’t embark on that. But thinking about this almost incredible episode does tell one something about the nature of civilisation. It shows that however complex and solid it seems, it is actually quite fragile. It can be destroyed. 

What are its enemies?

Well, first of all fear — fear of war, fear of invasion, fear of plague and famine, that make it simply not worthwhile constructing things, or planting trees or even planning next year’s crops. And fear of the supernatural, which means that you daren’t question anything or change anything. The late antique world was full of meaningless rituals, mystery religions, that destroyed self-confidence. And then exhaustion, the feeling of hopelessness which can overtake people even with a high degree of material prosperity. 

There is a poem by the modern Greek poet, Cavafy, in which he imagines the people of an antique town like Alexandria waiting every day for the barbarians to come and sack the city. Finally the barbarians move off somewhere else and the city is saved; but the people are disappointed — it would have been better than nothing. Of course, civilisation requires a modicum of material prosperity—

What civilization needs:

confidence in the society in which one lives, belief in its philosophy, belief in its laws, and confidence in one’s own mental powers. The way in which the stones of the Pont du Gard are laid is not only a triumph of technical skill, but shows a vigorous belief in law and discipline. Vigour, energy, vitality: all the civilisations—or civilising epochs—have had a weight of energy behind them. People sometimes think that civilisation consists in fine sensibilities and good conversations and all that. These can be among the agreeable results of civilisation, but they are not what make a civilisation, and a society can have these amenities and yet be dead and rigid.