Here Chesterton compares the Christian devotion to preserving non-Christian heritage with his perception of the Islamic practice. The Omar mentioned is the Caliph under whose command Jerusalem was sieged and conquered in 638:
The wild men that rode behind Omar the Arab would
have thought nothing of tearing every page of Plato in pieces.
For it is the nature of all this outer nomadic anarchy that it is
capable sooner or later of tearing anything and everything in pieces;
it has no instinct of preservation or of the permanent needs of men.
Where it has passed the ruins remain ruins and are not renewed;
where it has been resisted and rolled back, the links of our long
history are never lost. As I went forward the vision of our
own civilisation, in the form in which it finally found unity,
grew clearer and clearer; nor did I ever know it more certainly
than when I had left it behind.
G. K. Chesterton
The New Jerusalem, 1920
Ch. 1
