In this book, I make use of an idea from economics to suggest how noble human tendencies might not only have survived the ruthless pressures of the material world, but actually have been nurtured by them. The idea rests on a simple paradox, namely, that in many situations the conscious pursuit of self-interest is incompatible with its attainment. We are all comfortable with the notion that someone who strives to be spontaneous can never succeed. So too, on brief reflection, will it become apparent that someone who always pursues self-interest is doomed to fail.