DOCTOR: I'm old and I am wise, but I am most definitely silly. And I am certainly never a grown up!

DOCTOR: You know, I love it when people try to kill me. It means I’m on the right track.

DOCTOR: Who's she?

SARDICK: Nobody important.

DOCTOR: Nobody important. Blimey, that's amazing. Do you know, in nine hundred years of time and space, I've never met anyone who wasn't important before.

DOCTOR: The least important things, sometimes, my dear boy, lead to the greatest discoveries.

DOCTOR: But you can't rewrite history! Not one line!

DOCTOR: As we learn about each other, so we learn about ourselves.

DOCTOR: If you could touch the alien sand and hear the cries of strange birds and watch them wheel in another sky, would that satisfy you?