Shutting the stable door when the horse has gon

Every night as Bill the bat went swooping by the little cottage to hunt, he heard a nightingale singing in its cage by the open window. One night he stopped, and perched on the edge of the roof.

"why do you only sing at night?" he asked the nightingale. " It's because I was so busy singing in the daytime that I was caught," she replied. "Now I will only sing at night." Bill sniffed and looked down his beak at her. "Not much good being careful now," he said. "you should have thought of that before they caught you." And he went gliding away into the night.