The failures that ought to trouble us are not the hard ones. Famine relief is complicated; peace settlements are complicated; climate is complicated. The troubling failures are the easy ones. Conflicts that run for thirty years and end on terms both sides could have written in an afternoon. Warnings filed, costed, and ignored until the water arrives. Men in office whom any competent hospital administrator would outperform by lunchtime. Every news bulletin carries three or four of these, and they are not difficult problems badly solved. They are simple problems not solved at all.

And the second half of the evidence is worse than the first. Literacy, science, statistics, institutions, computation, now machines that reason faster than we do—every measure of our capacity has climbed for four centuries. The rate at which obvious things go undone has not fallen with it. When a variable rises steeply and the outcome does not move, one is not looking at the governing variable.

This book takes four serious explanations for that gap—incentives, ignorance, inherited instinct, and bad institutions—grants each of them everything it can honestly claim, and then measures what is left over. Something is left over. It is the same shape at every scale, from a marriage that ends over nothing to an empire that walks into a war nobody wanted.

Faced with a stubborn residue, the reasonable thing is to go back and look at an explanation that was taken off the books without ever being disproved. It is two thousand years old. It holds that the world is good in its making and wounded in its condition, that the wound is not stupidity and cannot be repaired by cleverness, and that the cure is offered continually and refused. Nothing in this book is new. The Fathers said all of it, and said it better.

What the old explanation offers, and no rival offers, is a mechanism—and it is set out in the one parable that Christ took the trouble to explain. A sower goes out.