Graham Hess: Everybody in this family needs to just calm down and eat some fruit or something.
Bo: There's a monster outside my room, can I have a glass of water?
Graham Hess: Swing away Merrill. Merrill... swing away.
Morgan: I think God did it.
Officer Caroline: Merrill... how's work at the gas station?
Merrill: Stimulating.
Graham Hess: What are you thinking about?
Bo: Why do you talk to Mom when you're by yourself?
Graham Hess: Makes me feel better.
Bo: Does she ever answer back?
Graham Hess: No.
Bo: She never answers me either.
Graham Hess: It's happening.
Graham Hess: See this is why we're not watching TV, people become obsessed.
Graham Hess: You're scaring your sister.
Bo: I'm already scared.
Officer Caroline: What kind of a machine bends a stalk of corn without breaking it?
Graham Hess: It can't be by hand, it's too perfect.
Bo: Are you in my dream too?
Merrill: There are a lot of things I can take, and some things I can't. But what I can't take is when my older brother, who's everything that I want to be, starts losing faith in things. I saw that look in your eyes last night. I don't ever want to see that look in your eyes again.
Merrill: Move children! Vámanos.
Graham Hess: There is no-one looking out for us. We are all alone.
Ray Reddy: Don't open my pantry, Father. I found one of them in there and I locked him in.
Caroline: Old Mrs. Kendleman twisted her ankle, as she puts it, diving for her life when a bunch of school kids rode down the sidewalk on skateboards. She went down to Thornton's store this morning and started spitting on the new skateboards. Spitting! By the time I got there, Mrs. Kendlemen had sprayed the whole damn place. And she must have had a cold or something. I'm telling you, I won't eat for a week. So, what happened to your crops?
Graham Hess: Morgan, after you were born, the doctor gave you to your mother. When she first looked at you, you just stared right back. You both just stared at each other for longest time, and you didn't even cry.
Merrill: Excluding the possibility that a female Scandinavian Olympian was running around outside our house last night, what else might be a possibility?
Officer Caroline: I'm not done asking questions. And I don't appreciate sarcasm.
Merrill: Move, children. Vamanos.
Graham Hess: We're going to board up every window in this house.
Merrill: How do you know boards will do anything?
Graham Hess: Because they seem to have trouble with pantry doors.
Answer: It's left unclear, though the film proposes several possible theories, and there are other possible explanations as well. One major theory brought up in the film is that the aliens were there to acquire Earth's resources after using up their own. Another theory proposed at the end of the movie is that the aliens wanted humans for whatever reason, as a radio DJ mentions seeing his friend's family being dragged away. There is also a very popular fan theory that the aliens are supposed to represent demons that are merely there to create chaos and test the moral strength of humanity, as the film is ultimately about Graham losing and then regaining his faith, although this is more subtext than anything and may not be literally true.