Here, Chesterton nails two curious things that we do all the time. We have a grand new idea, but in our minds we legitimize it by comparing it to great things in the past. And we have grand new idea, and we imagine that the people in the past were thinking the same thing as us all along.
It is chiefly interesting as evidence that the boldest plans for the future invoke the authority of the past; and that even a revolutionary seeks to satisfy himself that he is also a reactionary. There is an amusing parallel example in the case of whatis called feminism. In spite of all the pseudoscientific gossip about marriage by capture and the cave-man beating the cave-woman with a club, it may be noted that as soon as feminism became a fashionable cry, it was insisted that human civilisation in its first stage had been a matriarchy. Apparently it was the cave-woman who carried the club. Anyhow all these ideas are little better than guesses; and they have a curious way of following the fortune of modern theories and fads.
-G.K. Chesterton, The Everlasting Man, p.66