You are caught in a traffic jam in Karachi and a beggar raps on your window. He displays a withered limb or (take your pick) a twitching stump, a bleeding abscess, an arm bent like a question mark, hands with no fingers, a goutish tumor, a cleft lip, a scorched face. The look in his yellowed eyes says, “You are not going to ignore this, are you?” The window is rolled up, the air-conditioning is on, the doors are locked and neither the traffic nor the beggar moves. After an interval, he raps again. In the evenings, as the diseased and afflicted limp out of the darkness, evoking a macabre scene from “Night of the Living Dead,” the situation fluctuates between grotesque and absurd, repulsive and fascinating. Your car is an existential bubble on wheels; you don’t want this, nobody would want this, but it is worthwhile. The rapping on the window—how should America respond?