Love essentially involves desire. But what is desire? And what sorts of desire are characteristic of love? ‘Desire’ explains that some of the things lovers want are features desirable in any friendly relationship: trust, intimacy, emotional resonance, companionship, concern for one another’s welfare. Erotic love adds more specific desires. The full cycle of desire and pleasure has five stages: (1) desire motivates us to pursue a goal; (2) pursuit secures the object of desire; (3) the object of desire causes pleasure; (4) pleasure triggers the reward mechanism; and (5) that mechanism reinforces the desire. The curse of satisfaction, the altruists’ dilemma, and two types of desire—reason-based and reason-free desire—are also considered.