I think that books inspire us making us understan the world and ourselves. I think that some of the best books have a quote that sums up what the book is about.
Here is some of my favourite quotes from books

"It's not the face, but the expression on it. It's not the voice, but the words you say. It's not how you look in that body, but what you do with it. You Are Beautiful." - Ian O'Shea, The Host by Stephanie Meyer

"In the moment when I truly understand my enemy, Understand him well enough to defeat him, then in the very moment I also love him." - Ender Wiggin, Ender's Game by Orson Scott Card