Natural Law, Constitutionalism, Reason of State, and War: Counter-Reformation Spanish Political Thought (Volumes I and II) aims at understanding how Spanish thinkers in the sixteenth and early seventeenth centuries approached the emerging institution of the state. Both volumes are divided evenly into four distinct but related parts that cover the Spaniards’ central concerns. In the first part, a fundamental question is asked: Is the state a natural institution? In the second, the theme is determining the best form of government. The third part is concerned with the imperative need to define the ethical boundaries beyond which the state must not trespass. Finally, the fourth part examines the question of war as an instrument of policy.