The first section is about Virgil (author of the Aeneid, the story of the fall of Troy leading to the founding of Rome)..
The themes of Virgil were specially and notably the normal themes and nowhere more than in morals; piety and patriotism and the honor of the countryside. And we may well pause upon the name of the poet as we pass into the autumn of antiquity; upon his name who was in so supreme a sense the very voice of autumn, of its maturity and its melancholy of its fruits of fulfilment and its prospect of decay. Nobody who reads even a few lines of Virgil can doubt that he understood what moral sanity means to mankind. Nobody can doubt his feelings when the demonds were driven in flight before the household gods. But there are two particular points about him and his work which are particularly important to the main thesis here. The first is that the whole of his great patriotic epic is in a very peculiar sense founded upon the fall of Troy; that is upon an avowed pride in Troy although she had fallen.
In tracing to Trojans the foundation of his beloved race and republic, he began what may be called the great Trojan tradition which runs through medieval and modern history. We have already seen the first hint of it in the pathos of Homer about Hector. But Virgil turned it not merely into a literature but into a legend. And it was a legend of the almost divine dignity that belongs to the defeated. This was one of the traditions that did truly prepare the world for the coming of Christianity and especially of Christian chivalry. This is what did help to sustain civilisation through the incessant defeats of the Dark Ages and the barbarian wars; out of hwich what we call chivalry was born. It is the moral attitude of the man with his back to the wall; and it was the wall of Troy. All through medieval and modern times this version of the virtues in the Homeric conflict can be traced in a hundred ways cooperating with all that was akin to it in Christian sentiment. Our own countrymen, and the men of other countries, loved to claim like Virgil that their own nation was descended from the heroic Trojans. All sorts of people thought it was the most superb sort of heraldry to claim to be descended from Hector. Nobody seems to have wanted to be descended from Achilles. (pgs. 184-185)
This is getting hard - so interesting that I don't know what to simply highlight!
That is why the popularisation of the Trojan origin by Virgil has a vital relation to all those elements that have made men say that Virgil was almost a Christian. It is almost as if two great tools or toys of the same timber, the divine and the human, had been in the hands of Providence; and the only thing comparable to the Wooden Cross of Calvary was the Wooden Horse of Troy. So, in some wild allegory, pious in purpose if almost profane in form, the Holy Child might have fought the Dragon with a wooden sword and a wooden horse. (pgs. 185-186)
I love how Chesterton develops the themes of shepherds and philosophers and then (later in the book) shows us how they relate to the shepherds and Magi in the story of Christmas. This is just a little piece of the theme here.
There is nothing more artificial than the cry of artificiality as directed against the old pastoral poetry. We have entirely missed all that our fathers meant by looking at the externals of what they wrote. People have been so much amused with the mere fact that the china shepherdess was made of china that they have not even asked why she was made at all...
In short, we have only to ask why there is a chian shepherdess and not a china shopkeeper. Why were not mantelpieces adorned with figures of city merchants in elegant attitudes; of ironmasters wrought in iron or gold speculators in gold? ... Because the ancient instinct and humour of humanity have always told them, under whatever conventions, that the conventions of complex cities were less really healthy and happy than the customs of the countryside.