"Entertaining a notion, like entertaining a baby cousin or entertaining a pack of hyenas, is a dangerous thing to refuse to do. If you refuse to entertain a baby cousin, the baby cousin may get bored and entertain itself by wandering off and falling down a well. If you refuse to entertain a pack of hyenas, they may become restless and entertain themselves by devouring you. But if you refuse to entertain a notion - which is just a fancy way of saying that you refuse to think about a certain idea - you have to be much braver than someone who is merely facing some blood-thirsty animals, or some parents who are upset to find their little darling at the bottom of a well, because nobody knows what an idea will do when it goes off to entertain itself."