We measure rainfall and radiation, the depths of space and the emptiness of atoms, calories and steps, happiness and fear. If we could not measure then we could not observe the world around us we could not experiment, learn, and co-operate. But why did this urge to measure flourish? And when did measurement become ubiquitous?It is an incredible story that spans hunter-gatherer societies to ancient Egyptians, the French Revolution to the relentless quantification of the twenty-first century self. It is a tale that tracks humanitys search for dependable truths in a chaotic universe. Full of mavericks and visionaries, adventure and