- If there's anything you don't want me to see, just imagine a door, and close it. <...> Actually, there's a door there, you may want to just... ooh... <...> Sorry, you might find old memories reawakening, side effect.
- Oh, such a lonely childhood!
- It'll pass.
- Oh, Doctor, so lonely, so very very alone!
- What do mean, lonely? You've never been alone in your whole life- wait a minute, when did you start calling me Doctor?
- Such a lonely little boy. Lonely then and lonelier now! How can you bear it?
- How did you do that?
- A door, once opened, may be stepped through in either direction.
(c) "Doctor Who", 2.4.