It may also be powered by cosmopolitanism, by histories, and journalism, and memoirs, and realistic fiction, and travel, and literacy, which allows you to project yourself into the lives of other people that formerly you may have treated as sub-human, and also to realize the accidental contingency of your own station in life, the sense that "" there but for fortune go I. "" Whatever its causes, the decline of violence, I think, has profound implications. It should force us to ask not just, why is there war? But also, why is there peace? Not just, what are we doing wrong? But also, what have we been doing right?