This book compares cultures of natural philosophy in Denmark and Sweden from the Reformation to around 1700. Rather than treating natural philosophers as individuals, it analyses the rise of particular circles and cultures, which stimulated new approaches to the study of nature in talented individuals. As a study of culture, it does not treat natural philosophy as an autonomous phenomenon, but connects it to the political, social and religious framework of the surrounding society. The book ventures to explain the highly different national style of natural philosophy in Denmark and Sweden, and why the flourishing scientific culture in Copenhagen in the mid-17 th century had withered only few decades later, while science in Sweden attained momentous prestige and support in the decades around 1700.