Book excerpt: The conflict and contact between Muslims and Christians in the Middle Ages is among the most important but least appreciated developments of the period from the seventh to the fourteenth century. Michael Frassetto argues that the relationship between these two faiths during the Middle Ages was essential to the cultural and religious developments of Christianity and Islam—even as Christians and Muslims often found themselves engaged in violent conflict. Frassetto traces the history of those conflicts and argues that these holy wars helped create the identity that defined the essential characteristics of Christians and Muslims. The polemic works that often accompanied these holy wars was important, Frassetto contends, because by defining the essential evil of the enemy, Christian authors were also defining their own beliefs and practices. Holy war was not the only defining element of the relationship between Christians and Muslims during the Middle Ages, and Frassetto explains that everyday contacts between Christian and Muslim leaders and scholars generated more peaceful relations and shaped the literary, intellectual, and religious culture that defined medieval and even modern Christianity and Islam.