The Doctor: What's the use of a good quotation if you can't change it?

The Brigadier: Naturally enough, the only country that could be trusted with such a role was Great Britain.
The Doctor: Naturally. I mean, the rest were all foreigners.

The Doctor: As we learn about each other, so we learn about ourselves.

Russell: Who are you?
The Doctor: I've already told you. I am known as the Doctor. I'm also a Time Lord from the planet Gallifrey in the constellation of Kasterborous.
Russell: You're bonkers.
The Doctor: That's debatable.

The Doctor: When we were on the river we heard the unearthly babble of inhuman voices, didn't you, Romana?
Professor Chronotis: Oh, undergraduates talking to each other, I expect. I'm trying to have it banned.

Countess Scarlioni: Oh, Doctor, I'm quite convinced you're perfectly mad.
The Doctor: Only at my worst. Nobody's perfect.

The Doctor: You're a beautiful woman, probably.

[On oil]
The Doctor: It's about time the people who run this planet of yours realized that to be dependent on a mineral slime just doesn't make sense.

The Doctor: Deactivating a generator loop without the correct key is like repairing a watch with a hammer and chisel. One false move and you'll never know the time again.

The Doctor: Never cared much for the word "impregnable." Sounds a bit too much like "unsinkable."
Harry: What's wrong with "unsinkable"?
The Doctor: Nothing. As the iceberg said to the Titanic.
Harry: What?
The Doctor: Gloop, gloop, gloop, gloop, gloop, gloop, gloop.

The Doctor: Once upon a time there were three sisters, and they lived in the bottom of a treacle well. Their names were Olga, Marsha and Irene... Are you listening, Tillie? I feel disorientated.
Sarah: This is the disorientation centre.
The Doctor: That makes sense.

The Doctor: You can't rule the world in hiding. You've got to come out on the balcony sometimes and wave a tentacle.

The Doctor: You want me to volunteer, is that it? And if I don't?
White Guardian: Nothing.
The Doctor: You mean nothing'll happen to me?
White Guardian: Nothing. Ever.

Lord Palmderale: Are you in charge here?
The Doctor: No, but I'm full of ideas.

Brigadier: As long as he does the job, he can wear what face he likes.

Brigadier: Most of their work's so secret, they don't know what they're doing themselves.

Dalek: There is only one form of life that matters - Dalek life.

The Doctor: Marshal, you are quite mad.
Marshal: Only if I lose.

Adric: Will Romana be all right?
The Doctor: All right? She'll be superb.

The Doctor: Still, while there's life, there's six of one, half dozen of the other.
Master: Woolly thinking, Doctor.
The Doctor: Yes, but very comforting when worn next to the skin.

The Doctor: Maybe I am getting too young for this sort of thing.

The Doctor: There's no point in being grown up if you can't be childish sometimes.