Juan de Mariana's 1599 treatise On the King and the Education of the King has generally been regarded as one of the early stepping stones towards a modern pluralist and democratic thought. Yet when his work is studied in detail and put into the context of Spanish and the wider European politics, and the ongoing dynamics of the Catholic Reformation, it can convincingly be argued that this is a misleading view. Instead, this book presents the case for viewing Mariana as a champion of Christian moral reform, concerned with the transformation of the Spanish monarchy under the leadership of the Church.