"He'll be coming and going," [Mr Beaver] had said. "One day you'll see him and another you won't. He doesn't like being tied down - and of course he has other countries to attend to. It's quite all right. He'll often drop in. Only you mustn't press him. He's wild, you know. Not like a tame lion."
C.S. Lewis, The Lion, the Witch and the Wardrobe