AMY: One little girl crying. So?

DOCTOR: Crying silently. I mean, children cry because they want attention, because they're hurt or afraid. But when they cry silently, it's because they just can't stop. Any parent knows that.

AMY: Are you a parent?

DOCTOR: Hundreds of parents walking past who spot her and not one of them's asking her what's wrong, which means they already know, and it's something they don't talk about. Secrets. They're not helping her, so it's something they're afraid of. Shadows, whatever they're afraid of, it's nowhere to be seen, which means it's everywhere. Police state.