Cat in the Box

Mrs. Smith was walking down the street one day carrying a small box with holes punched in the top.

"What's in that box?" Mrs. Jones asked.

"A cat," Mrs. Smith answered.

"What for?"

"I've been dreaming about mice at  night, and I'm scared of mice.  The cat is to catch them."

"But the mice you dream about are imaginary," said Mrs. Jones.

Mrs. Smith turned to her friend and whispered, "So is the cat."