CM wrote:

"Dr. Flonkenstein"

The cat was invisible!

Try to deny that!

Deny it?
Heck, no! I don't see the cat, so it must be invisible!
Since I don't see it, the invisible cat must exist! QED!

Oh, Darn!
I just spotted the cat, I can see it, so it must not exist.

Must be a different cat.  Wheezle's been here all night.

Vince B.