DOCTOR: I have a ship. It's called the TARDIS. That blue box. It harnesses technology that makes it bigger on the inside than on the outside. I could take you all. I could carry you to the stars. I... could find you a home that is safe and clean and everything you want.

LINDY: But... we couldn't travel with you.

RUBY: What? Why... Why not?

LINDY: Because you, sir, are not one of us. I mean, you were kind, although it was your duty to save me, obviously. I mean, screen-to-screen contact is just about acceptable, but... in person? That's impossible.