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 that they form."
Kublai Khan remains silent, reflecting. Then he adds:
- Why do you speak to me of the stones? It is only the arch that matters to me.
- Without stones there is no arch. (Invisible Cities, by Italo Calvino)