Quantifiable citizenship in the form of birth certificates, census forms, and immigration quotas is so ubiquitous that today it appears ahistorical. Yet before the modern colonial era, there was neither a word for "population" in the sense of numbers of people, nor agreement that monarchs should count their subjects. Much of the work of naturalizing the view that people can be represented as populations took place far outside government institutions and philosophical treatises. It occurred instead in the work of colonial writers who found in the act of counting a way to imagine fixed...