DOCTOR: Who's she?

SARDICK: Nobody important.

DOCTOR: Nobody important. Blimey, that's amazing. Do you know, in nine hundred years of time and space, I've never met anyone who wasn't important before.

“The least important things, sometimes, my dear boy, lead to the greatest discoveries.”

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

“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?”

“But you can't rewrite history! Not one line!”