Despite the ceaseless news about war, crime, and terrorism, violence has actually been in decline over long stretches of history. The key to explaining this decline is to understand the inner demons that incline us toward violence (such as revenge, sadism, and tribalism) and the better angels that steer us away. Thanks to the spread of government, literacy, trade, and cosmopolitanism, we increasingly control our impulses, empathize with others, bargain rather than plunder, debunk toxic ideologies, and deploy our powers of reason to reduce the temptations of violence.