Our reactions to others, and theirs to us, have a far-reaching biological impact, sending out cascades of hormones that regulate everything from our hearts to our immune systems, making good relationships act like vitamins—and bad relationships like poisons. We can “catch” other people’s emotions the way we catch a cold, and the consequences of isolation or relentless social stress can be life-shortening. Goleman explains the surprising accuracy of first impressions, the basis of charisma and emotional power, the complexity of sexual attraction, and how we detect lies. He describes the “dark side” of social intelligence, from narcissism to Machiavellianism and psychopathy. He also reveals our astonishing capacity for “mindsight,” as well as the tragedy of those, like autistic children, whose mindsight is impaired.