The Strauss–Howe generational theory, also known as the Fourth Turning theory or simply the Fourth Turning, describes a theorized recurring generation cycle in American history and global history. It was devised by William Strauss and Neil Howe. According to the theory, historical events are associated with recurring generational personas (archetypes). Each generational persona unleashes a new era (called a turning) lasting around 20–25 years, in which a new social, political, and economic climate (mood) exists. They are part of a larger cyclical "saeculum" (a long human life, which usually spans between 80 and 100 years, although some saecula have lasted longer). The theory states that a crisis recurs in American history after every saeculum, which is followed by a recovery (high). During