In The Sleep of Behemoth, Jehangir Yezdi Malegam explores the emergence of conflicting concepts of peace in western Europe during the High Middle Ages. Ever since the early Church, Christian thinkers had conceived of their peace separate from the peace of the world, guarded by the sacraments and shared only grudgingly with powers and principalities. To kingdoms and communities they had allowed attenuated versions of this peace, modes of accommodation and domination that had tranquility as the goal. After 1000, reformers in the papal curia and monks and canons in the intellectual...