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!

DOCTOR: Exotic alien swords are easy to come by. Aces are rare.

DOCTOR: Anybody remotely interesting is mad in some way or another.

DOCTOR: I don't suppose you've completely ignored my instructions and secretly prepared any Nitro Nine, have you?

ACE: What if I had?

DOCTOR: Naturally you wouldn't do anything so insanely dangerous as to carry it around with you, would you?

ACE: Of course not. I'm a good girl. I do what I'm told.

DOCTOR: Excellent. Blow up that vehicle.

DOCTOR: Every great decision creates ripples, like a huge boulder dropped in a lake. The ripples merge and rebound off the banks in unforeseeable ways. The heavier the decision, the larger the waves, the more uncertain the consequences.

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: You can always judge a man by the quality of his enemies.

SARAH: Please, don't die.

DOCTOR: A tear, Sarah Jane? No, don't cry. While there's life there's…

(The Doctor stops in preparation of his imminent regeneration)

DOCTOR: A straight line may be the shortest distance between two points, but it is by no means the most interesting.

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.

JO: We’re still on Earth, aren’t we?

DOCTOR: No, that’s impossible.

JO: Don’t you ever admit that you’re wrong?

DOCTOR: No, that’s impossible too.

JO: Who is he and how did he get in here?

THIRD DOCTOR: Well it's a bit difficult to explain, Jo.

JO: He's not one of them, is he?

THIRD DOCTOR:: Well, not so much one of them as one of us. One of me to be precise.

SECOND DOCTOR: Oh no, no, no, no. I'm sorry, my dear, I hate to be contrary but I can see he's a little bit confused, poor old chap, and I do feel you should have the correct explanation. You don't mind, do you.

THIRD DOCTOR:: Yes.

SECOND DOCTOR: I didn't think you would. You see, Jo. I may call you Jo, mayn't I? You see, he is one of me.

JO: Oh, I see. You're both Time Lords.

SECOND DOCTOR: Well quite. Well, not quite.

JO: Oh.

SECOND DOCTOR: Not, not just Time Lords. We're the same Time Lord.

THIRD DOCTOR:: Now please, you're only confusing my assistant. Jo, it's all quite simple. I am he and he is me.

JO: "And we are all together, goo goo ga joob?"

DOCTOR: No! Stop, you're making me giddy! No, you can't do this to me! No, no, no, no, no, no, no, no, no, no, no, no, no!

DOCTOR: Oh, my giddy aunt.

DOCTOR: It is too important. I must be sure. Oh dear. What pretty crockery this is. Sad really, isn't it? People spend all their time making nice things, and other people come along and break them.

DOCTOR: Well, this is gay!

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.