Relationships

Cats know exactly where they begin and end. When they walk slowly out the door that you are holding open for them and pause, leaving their tail just an inch or two inside the door, they know it. They know you have to keep holding the door open. That is why their tail is there. It is a cat's way of maintaining a relationship.

Ursula K. LeGuin quoted in Artful Sentences, Syntax as Style by Virginia Tufte to exemplify the chapter on dependant clauses.