Brings to the contemporary reader the major documents of the prolonged debate, revealing the ideas behind the conflict and relating them to the practical politics of the medieval world. Among the items recorded here are Henry IV's defiance of the papacy over the issue of lay investiture, the rise of the papacy to political power under "lawyer-pope" Innocent III, and Philip IV's humiliation of Boniface VIII. The author interprets these disputes and provides a clear narrative of church-state relations in the Middle Ages, explaining the issues that loomed so large before the men of the time.