You're more important to this Universe-well, to our Universe, then you can possibly know.
There. Right there. You're every bit as brilliant as he thought. That's exactly what happened.
We do. But we can't right now from here. The thing with this particular dimension change is, we can't get back. But, time freezes back home. I've already lived through all of that. We fix it. Rather spectacularly, I might add. You and me, Martha, one of my favorite people Miss Sarah Jane Smith, the always dashing Jack Harkness, my mum and my friend Mickey... It's all pretty amazing.