First, a story:
Late one night, a man searches for something in a parking lot. On his hands and knees, he crawls around a bright circle of light created by a streetlamp overhead.
A woman passes, stops, takes in the scene.
"What are you looking for? Can I help?"
"My car keys. Any chance you've seen them?"
"You dropped them right around here?"
"Oh, no. I dropped them way over there," he says, gesturing vaguely to some faraway spot on the other side of the lot.
"Then why are you looking here?"
The man pauses to consider the question.