The Crisis of Church and State 10501300 Author:Brian Tierney The western concept of the separation of church and state--indeed, the idea of the modern state itself--grew out of a centuries-long struggle between the kings and popes of medieval Europe. Few controversies have so indelibly influenced the course of Western civilization, both past and present. This book brings the major documents of the prolo... more »nged debate, revealing the ideas behind the conflict and relating them to the practical politics of the mediaeval world: lay investiture, the "lawyer pope" and Philip IV's humiliation of Boniface VIII.« less