DOCTOR: Professor Morgan, have you ever heard the expression “only the used key shines”?

MORGAN: What are you talking about?

DOCTOR: Wherever I go in the universe I invariably meet people like you - intelligent, knowledgeable people who, for reasons I can only guess at, reach a point in their lives when they arbitrarily decide to close their minds to anything new. You make it a point of personal pride to scoff, mock, and ridicule anybody who happens to inhabit a larger universe than the one in which you have chosen to imprison yourself - well that’s your business, you may believe I’m talking nonsense and I can’t help what you personally choose to believe, but I do know this - the only way to learn is to keep your mind open to the input of those who are more knowledgeable than yourself.