Tenth Doctor Month: Quote Of The Day #13

The Doctor: This is a Void ship.
Yvonne: And what is that?
The Doctor: Well it's impossible, for starters. I always thought it was just a theory, but.... It's a vessel designed to exist outside time and space. Traveling through the Void.
Rajesh Singh: And what's the Void?
The Doctor: The space between dimensions. There's all sorts of realities around us—different dimensions. Billions of parallel universes all stacked up against each other. The Void is in between, containing absolutely nothing. Imagine that—no light, no dark, no up, no down. No life. No time. Without end. My people called it The Void, the Eternals called it The Howling. But some people call it Hell. 

Army Of Ghosts (2006)