Your Essentials: Two Questions

I hate having to pick a favorite anything, and picking books is the absolute worst, so I highly appreciate this meme that's been going around my social media lately:

So it was very hard for me to respond to a recent request from a colleague: "If you could only choose two books for your library, what would they be?" After a good week of agonizing I gave her two titles to add to her list, but I wouldn't swear by them as my answer would probably be different any other day. I think really I'm still waiting to discover that book that I feel is all-encompassing enough to provide everything I'd want in a single package--and I know there are so many great books I have yet to try that I feel I'm selling them short to pick something else without giving them a chance. So I'm raising the question here without providing an answer.

A similar--though importantly different--question recently posed by The Atlantic: "What book or article would you make required reading for everyone on Earth?" Again, I don't have an immediate answer. Here are the ones they came up with.

You?