Modern Catholic political philosophy begins with a crisis within Christendom. The Wars of Religion ignited by the Protestant Reformation forced upon medieval Christendom a revaluation of the relationship between Church and State, and a reconsideration of the nature of sovereignty and of the relationship between citizens and regimes. Modern Catholic Political Philosophy: A History of Catholic Political Philosophy: Volume II begins with Thomas More and ending with Pope Leo XIII, this volume seeks to show how this sense of crisis shaped Catholic political thought from the sixteenth through the nineteenth centuries. Many of the writers treated in this volume have fallen in obscurity. Nonetheless, they are responsible for many of ideas that have become commonplace in modern political thought: division of political alternatives into “liberal” and “conservative”; notions of strong executive power; the centrality of social justice on behalf of international organization, all claim antecedent origins in the forgotten Catholic thinkers of this period. Together, they constitute a secret history of political thought that influences the main direction political thought takes in the twentieth century, and without which the political alternatives confronted in that century cannot be adequately understood.