Cats make one of the most satisfying sounds in the world: they purr. [...] Almost all cats make us feel good about ourselves because they let us know they feel good about us, about themselves, and about our relationship with them. A purring cat is a form of high praise, like a gold star on a test paper. It is a reinforcement of soemthing we would all like to believe about ourselves -- that we are nice.

Author: Roger A. Caras