| Quote #1
"Meg, don't get mad, but do you think maybe they don't know?"
It sounds like Meg could stand not knowing what's going on with her dad, so long as she's sure someone does know. This is similar to how when Meg does finally meet up with her father, she's fine not saving the world herself, so long as she believes he's going to do it. What's terrifying is knowing that even the people who are supposedly in charge don't have a clue.
| Quote #2
Meg looked. The dark shadow was still there. It had not lessened or dispersed with the coming of night. And where the shadow was the stars were not visible.
The impact of the Black Thing seems to be beyond logic – Meg doesn't yet have any reason to fear it, but she sill does.
| Quote #3
[Mrs. Whatsit] " That's another reason we wanted to prepare you on Uriel. We thought it would be too frightening for you to see it first of all about your own, beloved world." (5.107)
Pure evil is one thing, but pure evil visiting you at home is even worse. It's like the difference between a scary movie about kids going to visit a haunted house vs. one about kids whose own house turns out to be haunted – the latter is more terrifying, because it feels like nowhere, not even home, is safe.