This non-technical essay is a quick-fire analysis of the life cycle hypothesis—LCH—which remains at the core of economic thinking on consumption and saving to this day. It traces the origins of the of theory, describes its core concepts, and discusses the theory’s strength and weaknesses in the context of a macroeconomic analysis of population ageing. The essay is an updated synthesis of the ideas and results presented in my master’s thesis from the Copenhagen Business School. The first edition of the essay was published in November 2018. Updated editions might follow, which will be available here.