Through forceful storytelling and sharp insight, it reminds us all that economics is, at its root, the study of incentives-how people get what they want or need, especially when other people want or need the same thing. Among the questions it answers: Which is more dangerous, a gun or a swimming pool? If drug dealers make so much money, why do they still live with their mothers? What makes a perfect parent? And, of course: What do schoolteachers and sumo wrestlers have in common?