De jure naturae et gentium, “The law of nature and of nations,” is the title of Samuel Pufendorf's eight-volume masterpiece of philosophical jurisprudence, first published in 1672. It provides the tag by which an entire discourse is known, one that dominated legal philosophy at European universities for over two hundred years. Pufendorf's Protestant articulation of its principles was pivotal both for transmitting it to the Eighteenth Century and for giving it a history, which in his eyes began with his fellow-Protestant Hugo Grotius. In fact, however, its roots stretch back to the early Sixteenth Century, to the lawyers whom Philip Melanchthon gathered around him at Wittenberg and (more importantly for the future structure of the discourse) to the Catholic scholastic theologians who were originally based at Salamanca in Spain but subsequently spread out over the whole of Counter-Reformation Europe. In the confessional conflict that would burn throughout the Sixteenth and Seventeenth centuries, theologians on all sides used law to define the space of the political, and used the idea of natural law to underpin that space, even while shaping it differently according to their divergent narratives of sin and redemption. While the ius naturae et gentium was an academic genre, therefore, its content was not. It was a theory and a legitimation of the state, and the arc of its reasoning from nature to the nations ran through the institution of political power. The state and its power are constructed not so much upon right (ius) per se but on the potential for the violation of right (iniuria), and the demand for such violation to be vindicated, by law or ultimately by war. At its very barest—although this is to traduce the richness and complexity of the discourse—the ius naturae et gentium is thus a theory of legitimate violence. When it comes to animals, what we find is that they are systematically excluded from the potential to suffer violation of right and therefore from political space and political justice. As we shall see, however, this did not always mean that they were totally excluded from any kind of right or that every act of violence against them was always legitimate.