Book excerpt: This volume deals with the tracts - Latin and vernacular - published in the Netherlands on the comets of 1577 and 1618. Central to the book is the question of how these cometary appearances influenced the Aristotelian world view. This is the first lengthy examination of the decline of Aristotelian cosmology in the Netherlands. Its demonstration of the connection between cosmological and political views renders the book useful to historians of general Dutch history, as well as historians of science.