You don't have to read a whole book to learn from it and think about it deeply. Sometimes, all it takes is one sentence, such as this one from Hosseini's AND THE MOUNTAINS ECHOED:
"In her smile, Idris sees how little of the world he has known, even at thirty-five years of age, its savageness, its cruelty, the boundless brutality."
I just don't get it. I'm not even close to understanding why the world is teeming with savageness, cruelty, and boundless brutality. All I can do – all any of the good can do – is try, each day, to make a dent in the bad.