DOCTOR: Amazing thing, history. People always assume it's a straight line because they're in the middle of it. Viewed from outside it's more like a Möbius strip.

TENTH DOCTOR: What? What?

SIXTH DOCTOR: What are you afraid will happen if you pause for breath?

TENTH DOCTOR: That there won't be another.

SIXTH DOCTOR: Angel to the left of us, angel to the right

TENTH DOCTOR: Here I am, stuck in the middle with you

DOCTOR: Never be cruel. Never be cowardly. Hate is always foolish. Love is always wise. Always try to be nice, but never fail to be kind.

FIRST DOCTOR: There is good and there is evil. I left Gallifrey to answer a question of my own. By any analysis, evil should always win. Good is not a practical survival strategy - it requires loyalty, self-sacrifice and love. And so, why does good prevail? What keeps the balance between good and evil in this appalling universe? Is there some kind of logic? Some mysterious force?

BILL: Perhaps it's just... a bloke.

FIRST DOCTOR: A... bloke?

BILL: Yeah! Perhaps it's just some bloke, wandering around, putting everything right when it goes wrong.

FIRST DOCTOR: Well, that would be a nice story, wouldn't it?

BILL: That would be the best.

DOCTOR: Winning? Is that what you think it's about? I'm not trying to win. I'm not doing this because I want to beat someone, or because I hate someone, or because, because I want to blame someone. It's not because it's fun and God knows it's not because it's easy. It's not even because it works, because it hardly ever does. I do what I do, because it's right! Because it's decent! And above all, it's kind. It's just that. Just kind. If I run away today, good people will die. If I stand and fight, some of them might live. Maybe not many, maybe not for long. Hey, you know, maybe there's no point in any of this at all, but it's the best I can do, so I'm going to do it. And I will stand here doing it till it kills me. You're going to die too, some day. How will that be? Have you thought about it? What would you die for? Who I am is where I stand. Where I stand, is where I fall. Stand with me. These people are terrified. Maybe we can help, a little. Why not, just at the end, just be kind?

DOCTOR: Nothing’s sad until it’s over, and then everything is.

I am the Doctor. I'm coming to find you, and I will never, ever stop.

DOCTOR: Do you know what thinking is? It’s just a fancy word for changing your mind.

DOCTOR: Never give up. Never give in.

VASTRA: Good evening. I'm a Lizard Woman from the Dawn of Time, and this is my wife.

HOUSE: Fear me. I've killed hundreds of Time Lords.

DOCTOR: Fear me. I've killed all of them.

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: People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint, it's more like a big ball of wibbly-wobbly, timey-wimey... stuff.

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

DOCTOR: The Daleks have failed! Why don't you finish the job and make the Daleks extinct. Rid the Universe of your filth. Why don't you just die?

DALEK: You would make a good Dalek.

DOCTOR: I love humans. Always seeing patterns in things that aren’t there.

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.

MASTER: I know this is going to be hard to believe, Doctor, but for once I mean you no harm.

DOCTOR: Like Alice, I try to believe three impossible things before breakfast. Go on.

ADRIC: Now I'll never know if I was right.

DOCTOR: It's the end. But the moment has been prepared for.

DOCTOR: That's the trouble with computers. Always think in black and white. No aquamarines, no blues, no imagination.

DOCTOR: But the final responsibility is mine, and mine alone. Listen, if someone who knew the future pointed out a child to you and told you that that child would grow up totally evil, to be a ruthless dictator who would destroy millions of lives, could you then kill that child?

DOCTOR: You, Sir, are a NITWIT!