The Wolf in the Sheep's clothing

A wolf once decided to change his nature by changing his appearance, and thus get plenty to eat. He put on a sheepskin and accompanied the flock to the pasture. The shepherd was fooled by the disguise. When night fell, the shepherd shut up the wolf in the fold with the rest of the sheep and as the fence was placed across the entrance, the sheepfold was securely closed off. But when the shepherd wanted a sheep for his supper, he took his knife and killed the wolf.