The Doctor speaks up, all abuzz: "To generate that gravity field, and the funnel, you'd need a power source with an inverted self-extrapolating reflex of six to the power of six every six seconds." (Nobody likes a swot!) Rose notes that that's a lot of sixes (she doesn't even know: the original British airdates were either side of the week of June 6, 2006), and the Doctor reiterates that this too is impossible. Which it isn't; I mean, there's a black hole in the middle of our star system, for Pete's sake, but whatever. "It took us two years to work that out!" yells Zach, and the Doctor is coy and ever so modest: "I'm very good." Ida explains that we're there to figure all that out: "This power source is ten miles below through solid rock. Point Zero. We're drilling down to try and find it." Ida wants to "revolutionize modern science" with the power source. Jefferson, the security guy who tells you what to do and when, wants to use it "to fuel the Empire." And the Doctor takes off his glasses: "Or start a war." Toby's creepy -- "It's buried beneath us. In the darkness, waiting" -- but he's closer to the truth than any of them. "What's your job?" asks Rose. "Chief dramatist?" The Doctor smirks, and he and Rose smile at each other; at Toby. "Whatever it is down there is not a natural phenomenon," Toby continues. "And this planet once supported life. Eons ago, before the human race had even learned to walk." The Doctor remembers the strange elder writing and asks if that was Toby. He nods: "I copied it from fragments we found on earth by the drilling, but I can't translate it." The Doctor sighs that he can't either: "And that's saying something." Toby's getting excited: "There was some form of civilization. They buried something. Now it's reaching out. Calling us in." And you can't help going there, can you? There's a human urge we'll be talking about all throughout, to look under the bed and see if the monster's really there. It's a good impulse, even though you can't always tell that right away: when I say the other side of grace is also grace, it's this that I mean. Grace is the thing that picks you up off the floor, but it's also the thing that knocks you off your pedestal. Either way you keep growing and keep changing, because that's what it wants from you: better.