DOCTOR: My entire understanding of physical space has been transformed! Three-dimensional Euclidean geometry has been torn up, thrown in the air and snogged to death! My grasp of the universal constants of physical reality has been changed forever!

DOCTOR: Sorry. I've always wanted to see that done properly.

DOCTOR: We all change, when you think about it. We're all different people all through our lives. And that's okay, that's good, you've got to keep moving, so long as you remember all the people that you used to be. I will not forget one line of this. Not one day. I swear. I will always remember when the Doctor was me.

DOCTOR: The way I see it, every life is a pile of good things and bad things. The good things don’t always soften the bad things, but vice versa, the bad things don’t always spoil the good things or make them unimportant.

DOCTOR: Everybody lives, Rose. Just this once, everybody lives!

DOCTOR: There are worlds out there where the sky is burning, where the sea's asleep, and the rivers dream. People made of smoke, and cities made of song. Somewhere there's danger, somewhere there's injustice, and somewhere else the tea's getting cold. Come on, Ace, we've got work to do!

DAVROS: The Daleks shall become Lords of Time! We shall become all-

DOCTOR: - Powerful. Crush the lesser races. Conquer the galaxy. Unimaginable power. Unlimited rice pudding, et cetera, et cetera.

DOCTOR: I say, what a wonderful butler. He's so violent.

SARAH JANE: Doctor, you're being childish.

DOCTOR: Well of course I am. There's no point in being grown up if you can't be childish sometimes.

DOCTOR: Courage isn’t just a matter of not being frightened, you know. It’s being afraid and doing what you have to do anyway.

DOCTOR: One day, I shall come back — yes, I shall come back. Until then, there must be no regrets, no tears, no anxieties. Just go forward in all your beliefs, and prove to me that I am not mistaken in mine. Goodbye, Susan, goodbye, my dear.

DOCTOR: Fear makes companions of all of us.