From the Golf Generation to Generation X and Frank Schirrmacher's Methuselah Conspiracy: the popularity of the concept of generations is unmistakable. However, while the term has a rich spectrum of meanings throughout its history, only a small portion is evident in the current debate about generational justice or in the sociological definition of a generation as a community of experience. This monograph for the first time undertakes a comprehensive history of science and culture of the concept in its biological, political, educational, historiographical, and literary dimensions. The spectrum ranges from ancient conceptualizations to current demographic and biomedical debates.