The Book You Would Give To Everyone You Meet If You Could

I posed the following hypothetical to my friends on Facebook: "Here's the scenario. A mysterious benefactor contacts you and tells you the following: you can pick any book ever published and said benefactor will provide you with 100 free copies of said title, with no strings attached, save one - you must give a copy of said book to everyone you meet until your supply is exhausted. What do you pick?" Here are their responses, in the order I received them.