The Doctor frowned, scratching his head. "Hmm. Don't think that would work, though. If when we go back it's to the exact moment we left, then it's as if we were never really here at all, isn't it? Hell, maybe we aren't really here. I mean, even if I was to write something down on my skin, I wouldn't really expect it to be there when I got home. If I ever do get home," he finished morosely.