One day a wolf found a sheep's skin. He wrapped himself in it and sneaked into a sheep pen. He ate a lamb. He was sneaking up on a second lamb when the shepherd caught him.

"Don't throw me out," said the wolf.
"I'm one of your sheep."

"You're only pretending to be a sheep," said the shepherd.
"I'm no fool. I know you're really a wolf."
"How do you know?" asked the wolf. 
"I look like a sheep."
"You say you are a sheep," said the shepherd,

"but you act like a wolf."

The shepherd pulled a limb from a tree and beat the wolf with it. The wolf
leaped the fence and climbed a nearby hill.

He never went back to the sheep pen.