Because of his argument in support of tyrannicide under certain circumstances, Juan de Mariana has usually been considered a constitutionalist thinker. In his reassessment of Mariana's thought as exhibited in his De rege et regis institutione of 1599, Harald Braun persuasively disputes this reading. He argues for the difficulty of categorising Mariana as a political thinker; rather, for Braun, this Jesuit writer combined humanist, Scholastic and Tacitean elements into a unique composition. Displaying an Augustinian pessimism about human nature rather than a Thomistic optimism, Mariana departed from the general Scholastic account of the origins of civil society as well as from universal principles based on either natural or customary law. Ever since the original fall, civil society has declined progressively and irreparably. Mariana held the contemporary Spanish nobility in contempt, unfit for a role in government. His radicalism, according to Braun, consisted in his emphatic recommendation that the government of Spain be entrusted, under the king, to the secular clergy, that is to the bishops, much in the manner of the prince-bishops of Germany. Braun's study, as he claims, is the first to point out this major feature of Mariana's thought. Mariana also deplored the control over the Church exercised by the Spanish monarchy. On the other hand Braun notes that Mariana scarcely addressed the issue of the role of the papacy with regard to Spain or other states, a topic usually addressed by Catholic authors of the time. De rege et regis institutione was intended above all as an instruction for Philip iii of Spain who came to the throne as a twenty-year-old in 1598, and it belongs at least loosely to the body of literature aimed at the reform of the Spanish state produced by the arbitristas in the late sixteenth and early seventeenth century. Prudence stood out for Mariana as for many contemporaries as the dominant virtue desirable in the prince, since it guided him in adapting to the ever-changing political constellation. Mariana wanted to restrain the prince through education and the exercise of prudence, virtue and moderation rather than law. He impressed on the prince the need to secure the consent of his subjects, as did many contemporary political writers such as Justus Lipsius whom Braun considers the political thinker closest to Mariana. The critical passage on tyrannicide, Braun shows, was meant above all not as a justification of such a measure, though it could be understood in this way, but as a warning to the prince of the fate that awaited him should he allow his government to degenerate into tyranny. Uniformity of religion was stressed as necessary to preserve the peace in Spain at a time when religious conflict convulsed much of Europe, and Mariana urged the full integration of New Christians into Spanish society. For his instruction Mariana drew heavily for historical examples on his classic History of Spain that had appeared in 1592. Braun does not take up Mariana's treatment of war and the military where one finds also a mixture of Scholastic and Tacitean elements. The author may underestimate the Scholastic element in Mariana, but this is an important book on a major political writer of early modern Spain.