Marco Polo describes a bridge, stone by stone.
“But which one is the stone that holds the bridge up?” asks Kublai Khan.
“The bridge is not held up by this stone or that stone,” replies Marco, “but by the arc that they form.”
Kublai Khan remains silent, thinking. Then he continues, “Why do you speak to me of stones? It’s only the arc that matters.”
Polo responds, “Without stones, there is no arc.”
—Calvino, Invisible Cities