where the light is

One night, a passerby came upon a drunk crawling in the gutter on his hands and knees underneath a streetlight. When the passerby asked what he was doing, the drunk said he was looking for his car keys.

The passerby offered to help in the search, but first asked if it was here that the drunk thought he'd lost his keys. The drunk replied no, that he didn't think he lost them here.

"They're down there," the drunk said, pointing down the dark street in the direction of the bar he'd just left.

"Then why are you searching here?!!" the stranger asked, flabbergasted.

"Because this is where the light is."