Two fish were swimming along a stream when they come upon a third fish which remarks, “The water is absolutely fine today.” The two carry on without a reply. Later upstream one of them says to the other, “What the heck is water?”
Talking fish is not the point of the little story, of course. I find it remarkable that we often miss what we take for granted, and don’t question what we are perpetually immersed in. What explains the unreasonable success of cities is not something that we ponder casually, even though virtually every one of us lives and earns one’s livelihood in one.