How we cite our quotes: (Chapter.Paragraph)
Quote #1
He wasn't going to let them win, that's what I think now. He wasn't going to stop hoping. If I killed him, at least he would die with a sliver of his humanity intact. (4.38)
To give up hope is to let the aliens win. That's one of the reasons that Cassie doesn't let herself do it.
Quote #2
The mind-blowing numbers didn't faze him. The fact that we'd gone from seven billion strong to a couple hundred thousand in four months didn't shake his confidence that our race would survive. (5.13)
Cassie's dad was an optimist. He was sure the human race would endure. Cassie has his persistence, but she isn't quite so sure.
Quote #3
The 1st Wave knocked us back to the eighteenth century. The next two slammed us into the Neolithic. We were hunter-gatherers again. Nomads. Bottom of the pyramid. But we weren't ready to give up hope. Not yet. (10.26-10.28)
What do you think it would take for Cassie to actually give up? Serious question.