The Gregorian Reform of the ninth and tenth centuries dealt with the critical issue of lay investiture, the practice through which the laypeople, mainly monarchs, appointed priests and bishops to positions of ecclesiastical power. When doing this, they invested them with two symbols of office. These two symbols were normally given by the pope: a shepherds crook, symbolizing the pastoral duties, and a ring, symbolizing the marriage of the priest or bishop to the Catholic Church. The severe abuse of monarchical power by the kings, which led to lay investiture, gave need for a reform by the popes.
The period of moderate reform began with the modest Pope Leo IX. He wrote the Collection of 74 Titles stating the papal powers. He also condemned and forbade several clerical abuses, the most serious of which were,
- Simony: the sale or purchase of spiritual offices and church positions
- Lay investiture
- Clerical marriage: the forbidden marriage of the clergy or celibate priests
Radical reform (1058 – 1061) began with the industrious Pope Nicholas II. The main reform he made was that of instituting the College of Cardinals to elect the popes. Before this it had been done by the Roman populace. He also fiercely condemned lay investiture.
However, when Pope Gregory VII, for whom the reform is named, was elected pope, the greatest struggle for power over the Catholic Church arose. Gregory wrote the Dictatus Papae which stated all powers of the papacy, similar to the Collection of 74 Titles.
However, the indignant Holy Roman Emperor Henry IV fully ignored the pope and his reforms, appointing several bishops and priests to high positions within his own realm (lay investiture). This sparked the Investiture Controversy between King Henry IV and Pope Gregory VII, two stubborn, unforgiving rivals.
The King defied Gregory over all regulations as to secular power over the Church and as a result was excommunicated and deposed. Excommunication is when the Pope cuts a person off from the Church and forbids him to receive the Sacraments. To be deposed was to be removed from office, whether secular or religious.
When Henry was excommunicated he begged for forgiveness, which was granted by the lenient pope. Yet, when he regained all his previous powers, the emperor continued performing lay investiture. Finally, the pope excommunicated Henry permanently (1080) but the powerful king was able to banish Gregory, who died in exile. “I have loved justice and hated iniquity, therefore I die in exile.”
The end of the lay investiture controversy finally occurred in 1122, during the Concordat of Worms.