In the East the continuity of culture has only been interrupted by negative things that Islam has done.
In the West it has been interrupted by positive things that Christendom itself has done.

In the West the past of Christendom has its perspective blocked up by its own creations; in the East it is a true perspective of interminable corridors, with round Byzantine arches and proud Byzantine pillars.

That, I incline to fancy, is the real difference that a man come from the west of Europe feels in the east of Europe, it is a gap or a void.
It is the absence of the grotesque energy of Gothic, the absence of the experiments of parliament and popular representation, the absence of medieval chivalry, the absence of modern nationality.
In the East the civilisation lived on, or if you will, lingered on; in the West it died and was reborn.

But for a long time, it should be remembered, it must have seemed to the East merely that it died.
The realms of Rome had disappeared in clouds of barbaric war, while the realms of Byzantium were still golden and gorgeous in the sun.
The men of the East did not realise that their splendour was stiffening and growing sterile, and even the early successes of Islam may not have revealed to them that their rule was not only stiff but brittle.
It was something else that was destined to reveal it.
The Crusades meant many things; but in this matter they meant one thing, which was like a word carried to them on the great west wind.
And the word was like that in an old Irish song: "The west is awake." They heard in the distance the cries of unknown crowds and felt the earth shaking with the march of mobs; and behind them came the trampling of horses and the noise of harness and of horns of war; new kings calling out commands and hosts of young men full of hope crying out in the old Roman tongue "Id Deus vult," Rome was risen from the dead.
Almost any traveller could select out of the countless things that he has looked at the few things that he has seen.
I mean the things that come to him with a curious clearness; so that he actually sees them to be what he knows them to be.
I might almost say that he can believe in them although he has seen them.
There can be no rule about this realisation; it seems to come in the most random fashion; and the man to whom it comes can only speak for himself without any attempt at a critical comparison with others.
In this sense I may say that the Church of the Nativity at Bethlehem contains something impossible to describe, yet driving me beyond expression to a desperate attempt at description.
The church is entered through a door so small that it it might fairly be called a hole, in which many have seen, and I think truly, a symbol of some idea of humility.

It is also said that the wall was pierced in this way to prevent the appearance of a camel during divine service, but even that explanation would only repeat the same suggestion through the parable of the needle's eye.
Personally I should guess that, in so far as the purpose was practical, it was meant to keep out much more dangerous animals than camels, as, for instance, Turks.