Once upon a time there lived a farmer who raised chickens, wonderful, plump, juicy chickens that cooked up beautifully. But one summer a problem arose. It seemed that a fox had found a way to sneak into the pen where the chickens were kept, and it carried off a chicken every night. The farmer tried setting traps, but the fox was too smart to take the bait and get caught in the trap. The farmer tried staying awake and watching over the chicken pen, but he never did spot where it was that fox got in. No matter what the farmer tried, each morning when he checked, another chicken would be gone. One morning he noticed one chicken was gone, but another had a mark on it, as if the fox had tried to snatch two chickens at once.

"Aha," said the farmer to himself. "This is no longer a hungry fox; it…