“As we learn about each other, so we learn about ourselves.”

“You wanted advice you said. I never give it, never. But I might just say this to you. Always search for truth. My truth is in the stars and yours is here.”

“I tolerate this century, but I don't enjoy it. Have you ever thought what it's like to be wanderers in the fourth dimension? Have you? To be exiles? Susan and I are cut off from our own planet, without friends or protection. But one day we shall get back. Yes, one day. One day.”

“Fear makes companions of all of us.”

“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?”

ACE: But when?

DOCTOR: Are you looking for the butterfly?

ACE: What the one who beats its wings and tips the balance, so the hurricane forms? There isn't one, is there?

DOCTOR: Not often. They just tell the butterflies that to keep them happy.

ACE: I should have known.

DOCTOR: No, mostly they break the butterfly on the wheel of time. But over the decades, the millions of butterflies, the weather still changes somehow. That's time. A million, multi-coloured pieces of time.

“ (Blithely) Yes, I imagine so. It's quite clear that Frederick brought the car into the house, ran himself over with it, and put it back outside before he finally expired”