Rose: Who are you?
The Doctor: Do you know like we were sayin’? About the Earth revolving? It’s like when you’re a kid. The first time they tell you that the world’s turning and you just can’t quite believe it ’cause everything looks like it’s standin’ still. I can feel it. The turn of the Earth. The ground beneath our feet is spinnin’ at 1,000 miles an hour and the entire planet is hurtling around the sun at 67,000 miles an hour, and I can feel it. We’re fallin’ through space, you and me, clinging to the skin of this tiny little world, and if we let go…That’s who I am.