In the wake of the upheavals of the 1560s, new ideas about strengthening the power of rulers began to emerge. The central concept was sovereignty, first brought to public attention by the French jurist and lawyer Jean Bodin. Bodin wanted to defend the sovereign against external and internal threats, anchoring its power in divine and natural law but also giving him (or it) considerable scope for discretion. This chapter explores the origins and implications of this new interest in sovereignty, showing how it focused attention on the power of the ruler in relation to other sources of authority, notably the Church and the conscience of individuals. At Rome, Cardinal Bellarmine argued for the limits of state authority and for the indirect power of the papacy over magistrates, but other Catholics took different approaches. In particular, Giovanni Botero’s The Reason of State offered an approach to statecraft in which Church and state worked together. Meanwhile, in the Netherlands Justus Lipsius wove together classical texts, especially Tacitus, offering a route to stability and unity in a time of conflict; he acknowledged that conventional morality was sometimes inappropriate for a statesman who would need to adapt to the times. In France, Michel de Montaigne’s ground-breaking Essays combined personal reflection with subtle commentary on the world around him, as he sought to preserve his own integrity and maintain stability within his local community.