I recommended Harari’s previous book Sapiens in last summer’s reading list, and this provocative follow-up is just as challenging, readable, and thought-provoking. Homo Deus argues that the principles that have organized society will undergo a huge shift in the 21st century, with major consequences for life as we know it. So far, the things that have shaped society—what we measure ourselves by—have been either religious rules about how to live a good life, or more earthly goals like getting rid of sickness, hunger, and war. What would the world be like if we actually achieved those things? I don’t agree with everything Harari has to say, but he has written a smart look at what may be ahead for humanity.