The gods once disputed whether a living being could change its nature. Jupiter said "Yes," but Venus said "No." To settle the argument, Jupiter transformed a cat into a maiden and gave her to a young man as his wife.
The wedding took place, and the couple sat down to the feast. "See," Jupiter said to Venus, "how gracefully she behaves. Who could tell she was a cat just yesterday? Surely her nature has changed?"
"Wait a moment," Venus replied, and released a mouse into the room. The moment the bride saw it, she leaped from her seat and tried to pounce on the mouse.
"Ah, you see," said Venus, "Nature will out."