Science writer James Vincent tells the history of measurement from ancient Egypt through the contemporary quantified self movement, examining how the act of measuring has shaped civilization and consciousness. Each chapter focuses on a different measuring system or controversy: the creation of standard weights and measures in ancient societies, the French Revolution's invention of the metric system, the nineteenth-century battles over time zones, and contemporary debates about what algorithms should and shouldn't measure. Vincent shows that measurement is never neutral - choices about what to measure and how encode assumptions about value that shape what counts as real. The book examines how measurement standardization enabled both coordination and control, creating the infrastructure for modern states and economies while also enabling surveillance and exploitation. Vincent writes for general readers while engaging with scholarly debates about metrology and its history. His chapters on the metric system and on body mass index are particularly strong, showing how seemingly objective measures carry political histories. For anyone interested in the hidden assumptions behind numbers, or in understanding why measurement controversies generate such passion, this work provides accessible history that illuminates contemporary debates.