This work of intellectual and cultural history seeks to understand the recurring connection of teaching with contradiction in some major texts of the European Middle Ages. It moves comfortably between patristic and monastic exegesis, the Paris schools of the twelfth and thirteenth centuries, and late medieval Spain; between Latin and vernacular, between religious and secular. It assimilates the methodologies of religious and erotic texts, thereby displaying the investment of each in the sensuality and analytical power of language. The book begins by exploring Christian exegesis, in which biblical contradiction is the textual incarnation of a Truth that is at once and paradoxically singular and multiple. Exegesis teaches us of the possibility of maintaining the truth in one biblical proposition and, equally and simultaneously, in its apparent opposite. Under the aegis of dialectic and the Aristotelian rule of non-contradiction, however, we are next taught to read either/or, and to resolve contradiction not through suspension and multiplicity, as in exegesis, but rather through a judgment that favors either one proposition or the other. The writers studied here are John of Salisbury, whose Metalogicon is an ostensibly moderating critique of the intellectual extremism of the School of Paris logicians, and Peter Abelard, in whose life and writing the forces of contradiction work with maiming and illuminating violence.