The Doctor and Rose in “Father's Day”

[sternly] When we met, I said "travel with me in space", you said "no". Then I said it was a time machine.

It wasn't some big plan! I just saw it happening, and I thought... I can stop this.

Oh, I did it again. I picked another stupid ape! I should've known. It's not about showing you the universe, it never is. It's about the universe doing something for you!

So it's okay when you go to other times, and you save people's lives, but not when it's me saving my dad?!

I know what I'm doing! You don't. Two sets of us being there made that a vulnerable point.

But he's alive!

My entire planet died! My whole family! Do you think it never occurred to me to go back and save them?

But it's not like I've changed history! ...Not much. I mean, he's never gonna be a world leader, he's not gonna start World War Three or anything.

Rose, there's a man alive in the world who wasn't alive before; an ordinary man - that's the most important thing in creation! The whole world's different because he's alive!