History is full of events, but we have the sense that some were more signiﬁ cant than others. Some events reset the zeitgeist, the spirit of the times. Each case study in this book describes a particular episode of extraordinary cultural production, not just cultural reproduction-although that is well documented here, too-but remarkable cultural innovation in which people took social life in new directions. People invented or recast institutions, keeping and revitalizing some and discarding others. In many cases these transformative events altered the course of cultural evolution.