DOCTOR: There's this emperor and he asks this shepherd's boy, how many seconds in eternity? And the shepherd's boy says there's this mountain of pure diamond. It takes an hour to climb it, and an hour to go around it! Every hundred years, a little bird comes and sharpens its beak on the diamond mountain. And when the entire mountain is chiselled away, the first second of eternity will have passed! You must think that's a hell of a long time. Personally, I think that's a hell of a bird.