How do we define love? "It feels like hunger pains, and we use the same word. Pang. Perhaps this is why Cupid is depicted with a quiver of arrows, because love feels at times like being pierced in the chest. It is a wholesome violence. . . . People search for love as if it were a city lost beneath the desert dunes, where pleasure is the law, the streets are lined with brocade cushions, and the sun never sets." So writes Diane Ackerman in her insightful...