—And how do you know that you’re mad?

—To begin with —said the Cat—, a dog’s not mad. You grant that?

—I suppose so —said Alice.

—Well, then —the Cat went on—, you see, a dog growls when it’s angry, and wags its tail when it’s pleased. Now I growl when I’m pleased, and wag my tail when I’m angry. Therefore I’m mad.

—I call it purring, not growling —said Alice.

—Call it what you like —said the Cat—. Do you play croquet with the Queen to-day?

(Lewis Carroll, Alice in Wonderland, chapter VI)