"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them (the full list is here):
The author tries to understand the rationale behind Auschwitz, Treblinka, Bergen-Belsen. Dismissing stereotyped images of brutal Nazi torturers and helpless victims, Levi draws extensively on his own experiences to delve into the minds and motives of oppressors and oppressed alike. Describing the difficulty and shame of remembering, the limited forms of collaboration between inmates and SS goalers, the exploitation of useless violence and the plight of the intellectual, Levi writes about the issue of power, mercy and guilt, and their effects on the lives of the ordinary people who suffered so incomprehendingly.