In his geographical treatise of 1537, the Portuguese chronicler D. João de Castra explained that it would be possible to correlate all newly discovered lands with astronomical markers to produce an accurate map of the world. The result would be, he wrote, a “true and perfect geography.” The movement toward this vision, from the cartographic revolution of thirteenth-century Portolan charts to the use of surveying to map colonial territories in the nineteenth century, is a compelling narrative of the rationalization of space, and of the reinforcement of this trend by the pursuit of European imperial interests.