When thinking on the term "revolutionary," what comes to mind? Perhaps an invention of some sorts, or a movement that brings about peace and prosperity at its conclusion. However, instances that bring about change for the worse are usually regarded to as a setback or downfall. This is true in the case of Pope Gregory VII (aka Hildebrand). Hildebrand believes himself to be a revolutionary reformer when, in fact, he delays the progression of an era.
Before Gregory VII, the doctrine of royal theocracy justified lay investiture, thus making lay investiture acceptable to clergymen as well as to royalty. Henry III had been very generous with many bishops, granting them with great temporal power which, in turn, made many of them quite weathly. The clergy deemed this practice unacceptable when they learned of the tendency of the King to use bishops as royal servants. These clergymen (hereafter referred to as "reformers") wanted a return to the discipline of the early church. The death of the King (Henry III) made this reform much easier. Henry III, leaving only one infant son, named his predecessor as Conrad II who made some very unwise decisions when it came to appointing leaders to office. Among the leaders he chose was one of the most zealous of the reformers: Gregory VII.
Gregory VII thought himself God's instrument to "purify" the church, and he was going to do this by ridding the emperor of his investiture powers. He perhaps, did not realize the equal amount of zeal Henry III's son would put forth in the fight against his reforms. In 1075 Gregory VII issued a decree against lay investiture, threatening excommunication to those who opposed it, namely, Henry IV. Then began a chain of irreversible events: The decree enraged the King, thus causing him to call for the dissension of the Pope. This call for dissension causing the deposition and excommunication of Henry IV, the desperation of Henry IV to not be excommunicated, and the taking back of the sentence of excommunication.