Marco Polo describes a bridge, stone by stone.

“But which is the stone that supports the bridge”, Kublai Khan asks.

“The bridge is not supported by one stone or another”, Marco answers, but by the line of the arch they form.

Kublai Khan remains silent, reflecting, then he adds, “Why do you speak of the stones? It is only the arch that matters to me.”

Polo answers, “Without stones there is no arch.”

It is the desperate moment when we discover that this empire which had seemed to us the sum of all wonders, is an endless, formless ruin, that corruption’s gangrene has spread too far to be healed by our scepter, that the triumph over enemy sovereigns has made us the heirs of their long undoing.

— Invisible Cities (Italo Calvino)