The Investiture Controversy, also called Investiture Contest, was a conflict between church and state in medieval Europe over the ability to choose and install bishops (investiture) and abbots of monasteries and the pope himself. A series of popes in the 11th and 12th centuries undercut the power of the Holy Roman Emperor and other European monarchies, and the controversy led to nearly 50 years of civil war in Germany.
It began as a power struggle between Pope Gregory VII and Henry IV (then King, later Holy Roman Emperor) in 1076. The conflict ended in 1122, when Pope Callixtus II and Emperor Henry V agreed on the Concordat of Worms. The agreement required bishops to swear an oath of fealty to the secular monarch, who held authority "by the lance" but left selection to the church. It affirmed the right of the church to invest bishops with sacred authority, symbolized by a ring and staff. In Germany (but not Italy and Burgundy), the Emperor also retained the right to preside over elections of abbots and bishops by church authorities, and to arbitrate disputes. Holy Roman Emperors renounced the right to choose the pope.
In the meantime, there was also a brief but significant investiture struggle between Pope Paschal II and King Henry I of England from 1103 to 1107. The earlier resolution to that conflict, the Concordat of London, was very similar to the Concordat of Worms.
After the decline of the Western Roman Empire, investiture was performed by members of the ruling nobility (and was known as lay investure) despite theoretically being a task of the church. Many bishops and abbots were themselves usually part of the ruling nobility. Given that most members of the European nobility practiced primogeniture, and willed their titles of nobility to the eldest surviving male heir, surplus male siblings often sought careers in the upper levels of the church hierarchy. This was particularly true where the family may have established a proprietary church or abbey on their estate. Since a substantial amount of wealth and land was usually associated with the office of a bishop or abbot, the sale of church offices—a practice known as "simony"—was an important source of income for leaders among the nobility, who themselves owned the land and by charity allowed the building of churches. Emperors had been heavily relying on bishops for their secular administration, as they were not hereditary or quasi-hereditary nobility with family interests. They justified their power by the theory of the divine right of kings.
Many of the papal selections before 1059 were influenced politically and militarily by European powers, often with a king or emperor announcing a choice which would be rubber-stamped by church electors. The Holy Roman Emperors of Ottonian dynasty believed they should have the power to appoint the pope. Since the ascendance of the first of that line, Otto the Great (936–72), the bishops had been princes of the empire, had secured many privileges, and had become to a great extent feudal lords over great districts of the imperial territory. The control of these great units of economic and military power was for the king a question of primary importance due to its effect on imperial authority. It was essential for a ruler or nobleman to appoint (or sell the office to) someone who would remain loyal.
Problems with simony became particularly unpopular as Pope Benedict IX was accused of selling the papacy in 1045. Henry III, Holy Roman Emperor, reigning from 1046 to 1056, settled the papal schism and named several popes, the last emperor to successfully dominate the selection process. Six-year-old Henry IV became King of the Germans in 1056.
Pope Nicholas II
Benedict X was elected under the influence of the Count of Tusculum, allegedly by bribing the electors. Dissenting cardinals elected Pope Nicholas II in 1058 at Siena. Nicholas II successfully waged war against Benedict X and regained control of the Vatican. Nicholas II convened a synod in the Lateran on Easter in 1059. The results were codified in the papal bull In nomine Domini. It declared that leaders of the nobility would have no part in the selection of popes (though the Holy Roman Emperor might confirm the choice) and that electors would be cardinals (which would later evolve into the College of Cardinals) assembled in Rome. The bull also banned lay investiture. In response, all the bishops in Germany (who supported the Emperor) assembled in 1061 and declared all the decrees of Nicolas II null and void. Nevertheless, the elections of Pope Alexander II and Pope Gregory VII proceeded according to church rules, without the involvement of the Emperor.
Henry IV and Pope Gregory VII
In 1075, Pope Gregory VII, composed the Dictatus papae, though this was not published at the time, cataloging principles of his Gregorian Reforms. One clause asserted that the deposal of an emperor was under the sole power of the pope. It declared that the Roman church was founded by God alone – that the papal power (the auctoritas of Pope Gelasius) was the sole universal power; in particular, a council held in the Lateran Palace from 24 to 28 February the same year decreed that the pope alone could appoint or depose churchmen or move them from see to see. By this time, Henry IV was no longer a child, and he continued to appoint his own bishops. He reacted to this declaration by sending Gregory VII a letter in which he withdrew his imperial support of Gregory as pope in no uncertain terms: the letter was headed "Henry, king not through usurpation but through the holy ordination of God, to Hildebrand, at present not pope but false monk". It called for the election of a new pope. His letter ends, "I, Henry, king by the grace of God, with all of my Bishops, say to you, come down, come down!", and is often quoted with "and to be damned throughout the ages", which is a later addition.
The situation was made even more dire when Henry IV installed his chaplain, Tedald, a Milanese priest, as Bishop of Milan, when another priest of Milan, Atto, had already been chosen in Rome by the pope for candidacy. In 1076 Gregory responded by excommunicating Henry, and deposed him as German king, releasing all Christians from their oath of allegiance.
Enforcing these declarations was a different matter, but the advantage gradually came to be on the side of Gregory VII. German princes and the aristocracy were happy to hear of the king's deposition. They used religious reasons to continue the rebellion started at the First Battle of Langensalza in 1075, and for seizure of royal holdings. Aristocrats claimed local lordships over peasants and property, built forts, which had previously been outlawed, and built up localized fiefdoms to secure their autonomy from the empire.
Thus, because of these combining factors, Henry IV had no choice but to back down, needing time to marshal his forces to fight the rebellion. In 1077, he traveled to Canossa in northern Italy, where the Pope was staying in the castle of Countess Matilda, to apologize in person. The pope was suspicious of Henry's motives, and did not believe he was truly repentant. As penance for his sins, and echoing his own punishment of the Saxons after the First Battle of Langensalza, he wore a hair shirt and stood barefoot in the snow in what has become known as the Walk to Canossa. Gregory lifted the excommunication, but the German aristocrats, whose rebellion became known as the Great Saxon Revolt, were not as willing to give up their opportunity and elected a rival king, Rudolf von Rheinfeld. Three years later, Pope Gregory declared his support for von Rheinfeld and then on the Lenten synod of 7 March 1080 excommunicated Henry IV again. In turn, Henry called a council of bishops who proclaimed Gregory illegitimate. The internal revolt against Henry effectively ended that same year, however, when Rudolf von Rheinfeld died.
Henry IV named Guibert of Ravenna (who he had invested as bishop of Ravenna) to be pope, referring to Clement III (known by the Catholic Church as Antipope Clement III) as "our pope". In 1081, Henry attacked Rome and besieged the city with the intent of forcibly removing Gregory VII and installing Clement III. The city of Rome withstood the siege, but the Vatican and St. Peters fell in 1083. On the outskirts of the city, Henry gained thirteen cardinals who became loyal to his cause. The next year the city of Rome surrendered and Henry triumphantly entered the city. On Palm Sunday, 1084, Henry IV solemnly enthroned Clement at St. Peter's Basilica; on Easter Day, Clement returned the favour and crowned Henry IV as Emperor of the Holy Roman Empire.
Gregory VII was meanwhile still resisting a few hundred yards away from the basilica in the Castel Sant'Angelo, then known as the house of Cencius. Gregory called on his allies for help, and Robert Guiscard (the Norman ruler of Sicily, Apulia, and Calabria) responded, entering Rome on 27 May 1084. The Normans came in force and attacked with such strength that Henry and his army fled. Gregory VII was rescued; however the ferocity of the attack ultimately resulted in the plundering of Rome for which the citizens of Rome blamed Gregory VII. As a result, Gregory VII was forced to leave Rome under the protection of the Normans. Gregory VII was taken to Salerno by the Normans where he grew ill and died on 25 May 1085. The last words he uttered were, "I have loved justice and hated iniquity, and therefore I die in exile."
Upon the death of Gregory, the cardinals elected a new pope, Pope Victor III. He owed his elevation to the influence of the Normans. Antipope Clement III still occupied St. Peter's. When Victor III died, the cardinals elected Pope Urban II (1088–99). He was one of three men Gregory VII suggested as his successor. Urban II preached the First Crusade, which united Western Europe, and more importantly, reconciled the majority of bishops who had abandoned Gregory VII.
The reign of Henry IV showed the weakness of the German monarchy. The ruler was dependent upon the good will of the great men, the nobility of his land. These were technically royal officials and hereditary princes. He was also dependent on the resources of the churches. Henry IV alienated the Church of Rome and many of the magnates in his own kingdom. Many of these spent years in open or subversive rebellion. Henry failed to create a proper bureaucracy to replace his disobedient vassals. The magnates became increasingly independent, and the Church withdrew support. Henry IV spent the last years of his life desperately grasping to keep his throne. It was a greatly diminished kingdom.
Henry V, Holy Roman Emperor
The Investiture Controversy continued for several decades as each successive pope tried to diminish imperial power by stirring up revolt in Germany. These revolts were gradually successful. The reign of Henry IV ended with a diminished kingdom and waning power. Many of his underlords had been in constant or desultory revolt for years. Henry IV's insistence that Antipope Clement III was the real pope had initially been popular with some of the nobles, and even many of the bishops of Germany. But as years passed, this support was slowly withdrawn. The idea that the German king could and should name the pope was increasingly discredited and viewed as an anachronism from a by-gone era. The Empire of the Ottos was virtually lost because of Henry IV.
On 31 December 1105, Henry IV was forced to abdicate by and was succeeded by his son Henry V, who had rebelled against his father in favor of the papacy, and who had made his father renounce the legality of his antipopes before he died. Nevertheless, Henry V chose another antipope, Gregory VIII.
Henry V realised swift action and a change in his father's policy was necessary. Pope Paschal II rebuked Henry V for appointing bishops in Germany. The king crossed the Alps with an army in 1111. The pope, who was weak and had few supporters was forced to suggest a compromise, the abortive Concordat of 1111. Its simple and radical solution of the Investiture Controversy between the prerogatives of regnum and sacredoium proposed that German churchmen would surrender their lands and secular offices to the emperor and constitute a purely spiritual church. Henry gained greater control over the lands of his kingdom, especially those that had been in the hands of the church, but of contested title. He would not interfere with ecclesiastical affairs and churchmen would avoid secular services. The church would be given autonomy and to Henry V would be restored large parts of his empire that his father had lost. Henry V was crowned by Pope Paschal II as the legitimate Holy Roman Emperor. When the concessions of land were read in St. Peters, the crowd revolted in anger. Henry took the pope and cardinals hostage until the pope granted Henry V the right of investiture. Then he returned to Germany – crowned emperor and apparent victor over the papacy.
The victory was as short-lived as that of his father, Henry IV over Gregory VII. The clergy urged Paschal to rescind his agreement, which he did in 1112. The quarrel followed the predictable course: Henry V rebelled and was excommunicated. Riots broke out in Germany, a new Antipope Gregory VIII was appointed by the German king, nobles loyal to Rome seceded from Henry. The civil war continued, just as under Henry IV. It dragged on for another ten years. Like his father before him, Henry V was faced with waning power. He had no choice but to give up investiture and the old right of naming the pope. The Concordat of Worms was the result. After the Concordat, the German kings never had the same control over the Church as had existed in the time of the Ottonian dynasty. Henry V was received back into communion and recognized as legitimate emperor as a result.
Henry V died without heirs in 1125, three years after the Concordat. He had designated his nephew, Frederick von Staufen duke of Swabia, also known as Frederick II, Duke of Swabia as his successor. Instead, churchmen elected Lothair II. A long civil war erupted between the Staufen also known as Hohenstaufen supporters and the heirs of Lothar III. The result was the Hohenstaufen Frederick I 1152–1190 who came to power.
English investiture controversy (1102–07)
At the time of Henry IV's death, Henry I of England and the Gregorian papacy were also embroiled in a controversy over investiture, and its solution provided a model for the eventual solution of the issue in the empire.
William the Conqueror had accepted a papal banner and the distant blessing of Pope Alexander II upon his invasion, but had successfully rebuffed the pope's assertion after the successful outcome, that he should come to Rome and pay homage for his fief, under the general provisions of the Donation of Constantine.
The ban on lay investiture in Dictatus papae did not shake the loyalty of William's bishops and abbots. In the reign of Henry I, the heat of exchanges between Westminster and Rome induced Anselm, Archbishop of Canterbury, to give up mediating and retire to an abbey. Robert of Meulan, one of Henry's chief advisors, was excommunicated, but the threat of excommunicating the king remained unplayed. The papacy needed the support of English Henry while German Henry was still unbroken. A projected crusade also required English support.
Henry I commissioned the Archbishop of York to collect and present all the relevant traditions of anointed kingship. On this topic, the historian Norman Cantor would note: "The resulting 'Anonymous of York' treaties are a delight to students of early-medieval political theory, but they in no way typify the outlook of the Anglo-Norman monarchy, which had substituted the secure foundation of administrative and legal bureaucracy for outmoded religious ideology."
Concordat of London (1107)
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The Concordat of London, agreed in 1107, was a forerunner of a compromise that was later taken up in the Concordat of Worms. In England, as in Germany, the king's chancery started to distinguish between the secular and ecclesiastical powers of the prelates. Bowing to political reality and employing this distinction, Henry I of England gave up his right to invest his bishops and abbots while reserving the custom of requiring them to swear homage for the "temporalities" (the landed properties tied to the episcopate) directly from his hand, after the bishop had sworn homage and feudal vassalage in the commendation ceremony (commendatio), like any secular vassal. The system of vassalage was not divided among great local lords in England as it was in France, since the king was in control by right of the conquest.
Later developments in England
Henry I of England perceived a danger in placing monastic scholars in his chancery and turned increasingly to secular clerks, some of whom held minor positions in the Church. He often rewarded these men with the titles of bishop and abbot. Henry I expanded the system of scutage to reduce the monarchy's dependence on knights supplied from church lands. Unlike the situation in Germany, Henry I of England used the Investiture Controversy to strengthen the secular power of the king. It would continue to boil under the surface. The controversy would surface in the Thomas Becket affair under Henry II of England, the Great Charter of 1217, the Statutes of Mortmain and the battles over Cestui que use of Henry VII of England, and finally come to a head under Henry VIII of England.
Concordat of Worms (1122)
The European mainland experienced about 50 years of fighting, with efforts by Lamberto Scannabecchi, the future Pope Honorius II, and the 1121 Diet of Würzburg to end the conflict. On September 23, 1122, near the German city of Worms, Pope Callixtus II and Holy Roman Emperor Henry V entered into an agreement, now known as the Concordat of Worms, that effectively ended the Investiture Controversy. It eliminated lay investiture, while allowing secular leaders some room for unofficial but significant influence in the appointment process.
By the terms of the agreement, the election of bishops and abbots in Germany was to take place in the emperor's presence (or his legate's) as judge ("without violence") between potentially disputing parties, free of bribes, thus retaining to the emperor a crucial role in choosing these great territorial magnates of the Empire. But absent a dispute, the canons of the cathedral were to elect the bishop, monks were to choose the abbot. Beyond the borders of Germany, in Burgundy and Italy, the election would be handled by the church without imperial interference.
Callixtus' reference to the feudal homage due the emperor on appointment is guarded: "shall do unto thee for these what he rightfully should" was the wording of the privilegium granted by Callixtus. The emperor's right to a substantial imbursement (payment) on the election of a bishop or abbot was specifically denied.
The emperor renounced the right to invest ecclesiastics with ring and crosier, the symbols of their spiritual power, and guaranteed election by the canons of cathedral or abbey and free consecration. To make up for this and symbolise the worldly authority of the bishop which the pope had always recognised to derive from the Emperor, another symbol, the scepter, was invented, which would be handed over by the king (or his legate).
The two ended by promising mutual aid when requested and by granting one another peace. The Concordat was confirmed by the First Council of the Lateran in 1123.
In modern terminology, a concordat is an international convention, specifically one concluded between the Holy See and the civil power of a country to define the relationship between the Catholic Church and the state in matters in which both are concerned. Concordats began during the First Crusade's end in 1098.
The Concordat of Worms (Latin: Concordatum Wormatiense) is sometimes called the Pactum Callixtinum by papal historians, since the term "concordat" was not in use until Nicolas of Cusa's De concordantia catholica of 1434.[a]
In the long term, the decline of imperial power would divide Germany until the 19th century. Similarly, in Italy, the investiture controversy weakened the emperor's authority and strengthened local separatists.
While the monarchy was embroiled in the dispute with the Church, its power declined, and the localized rights of lordship over peasants increased, which eventually led to:
- Increased serfdom that reduced rights for the majority
- Local taxes and levies increased, while royal coffers declined
- Localized rights of justice where courts did not have to answer to royal authority
Selection of leaders
|Separation of church and state in the history of the Catholic Church|
The papacy grew stronger. Marshalling for public opinion engaged lay people in religious affairs increasing lay piety, setting the stage for the Crusades and the great religious vitality of the 12th century.
German kings still had de facto influence over the selection of German bishops, though over time, German princes gained influence among church electors. The bishop-elect would then by invested by the Emperor (or representative) with the scepter and, sometime afterwards, by his ecclesial superior with ring and staff. The resolution of the Controversy produced a significant improvement in the character of men raised to the episcopacy. Kings no longer interfered so frequently in their election, and when they did, they generally nominated more worthy candidates for the office.
The Concordat of Worms did not end the interference of European monarchs in the selection of the pope. Practically speaking, the king[which?] retained a decisive voice in the selection of the hierarchy. All kings supported King John of England's defiance of Pope Innocent III ninety years after the Concordat of Worms in the matter concerning Stephen Langton. In theory, the pope named his bishops and cardinals. In reality, more often than not, Rome consecrated the clergy once it was notified by the kings who the incumbent would be. Recalcitrance by Rome would lead to problems in the kingdom. For the most part it was a no-win situation for Rome. In this, the Concordat of Worms changed little. The growth of canon law in the Ecclesiastical Courts was based on the underlying Roman law and increased the strength of the Roman Pontiff.
Disputes between popes and Holy Roman Emperors continued until northern Italy was lost to the empire entirely, after the wars of the Guelphs and Ghibellines. Emperor Otto IV marched on Rome and commanded Pope Innocent III to annul the Concordat of Worms and to recognise the imperial crown's right to make nominations to all vacant benefices. The church would crusade against the Holy Roman Empire under Frederick II. As historian Norman Cantor put it, the controversy "shattered the early-medieval equilibrium and ended the interpenetration of ecclesia and mundus". Indeed, medieval emperors, which were "largely the creation of ecclesiastical ideals and personnel", were forced to develop a secular bureaucratic state, whose essential components persisted in the Anglo-Norman monarchy.
Kings continued to attempt to control either the direct leadership of the church, or indirectly through political means for centuries. This is seen most clearly in the Avignon Papacy when the popes moved from Rome to Avignon. The conflict in Germany and northern Italy arguably left the culture ripe for various Protestant sects, such as the Cathars, the Waldensians and ultimately Jan Hus and Martin Luther.
Authority and reform
Though the Holy Roman Emperor retained some power over imperial churches, his power was damaged irreparably because he lost the religious authority that previously belonged to the office of the king. In France, England, and the Christian state in Spain, the king could overcome rebellions of his magnates and establish the power of his royal demesne because he could rely on the Church, which, for several centuries, had given him a mystical authority. From time to time, rebellious and recalcitrant monarchs might run afoul of the Church. These could be excommunicated, and after an appropriate time and public penance, be received back into the communion and good graces of the Church.
Of the three reforms Gregory VII and his predecessors and successor popes had attempted, they had been most successful in regard to celibacy of the clergy. Simony had been partially checked. Against lay investiture they won only a limited success, and one that seemed less impressive as the years passed. During the time following the Concordat of Worms, the Church gained in both stature and power.
The wording of the Concordat of Worms was ambiguous, skirted some issues and avoided others all together. This has caused some scholars to conclude that the settlement turned its back on Gregory VII's and Urban II's genuine hopes for reform. The emperor's influence in episcopal was preserved, and he could decide disputed elections. If the compromise was a rebuke to the most radical vision of the liberty of the Church, on at least one point its implication was firm and unmistakable: the king, even an emperor, was a layman, and his power at least morally limited (hence, totalitarianism was unacceptable). According to the opinion of W. Jordan, the divine right of kings was dealt a blow from which it never completely recovered, yet unfettered authority and Caesaropapism was not something the later Mediaevals and Early Moderns understood by the phrase "by the grace of God" (which many of them ardently defended). If anything, a blow was dealt to subconsciously remaining pre-Christian Germanic feelings of "royal hail".[clarification needed]
Unification of Germany and Italy
It was the consequence of this lengthy episode that a whole generation grew up in Germany and Northern Italy in an atmosphere of war, doubt and scepticism. The papal backers had been busy propounding arguments to show that royal power was not of divine origin. They had been so successful that the moral authority of the Emperor had been undermined in the minds of many of his subjects. Serious divisions existed from this battle over the Investiture Controversy, which fractured large portions of the Holy Roman Empire in Germany and Italy. Davis argues these rifts were so deep and lasting that neither Germany nor Italy were able to form a cohesive nation state until the 19th century. A similar situation arose from the French revolution, which caused fractures in France that still exist. The effect of Henry IV's excommunication, and his subsequent refusal to repent left a turbulence in central Europe that lasted throughout the Middle Ages. It may have been emblematic of certain German attitudes toward religion in general, and the perceived relevance of the German Emperor in the universal scheme of things.
The catastrophic political consequences of the struggle between pope and emperor also led to a cultural disaster. Germany lost intellectual leadership in western Europe. In 1050, German monasteries were great centres of learning and art and German schools of theology and canon law were unsurpassed and probably unmatched anywhere in Europe. The long civil war over investiture sapped the energy of both German churchmen and intellectuals. They fell behind advances in philosophy, law, literature and art taking place in France and Italy. In many ways, Germany never caught up during the rest of the Middle Ages. Universities were established in France, Italy, Spain and England by the early 13th century. Notable are University of Bologna, 1088, University of Salamanca, 1134, University of Paris, 1150, Oxford University, 1167 and University of Cambridge, 1207. The first German university, the Heidelberg University was not established until 1386. It was immediately steeped in mediaeval nominalism and early Protestantism.
Development of liberty and prosperity in northern Europe
The political scientist Bruce Bueno de Mesquita argues that the Concordat of Worms contained within itself the germ of nation-based sovereignty that would one day be confirmed in the Peace of Westphalia (1648). The Concordat of Worms created an incentive structure for the rulers of the Catholic parts of Europe such that in the northern regions, local rulers were motivated to raise the prosperity and liberty of their subjects because such reforms helped those rulers assert their independence from the pope.
With the Concordat of Worms, the pope asserted direct personal control over the selection of bishops. Instead of myriad local customs, it all came down to negotiations between the pope and the local secular ruler. Therefore, the influence of the pope in the region became the common deciding factor across the Catholic parts of Europe.
As a consequence of the Concordat, if the local ruler rejected the pope's nominee for bishop, the ruler could keep the revenue of the diocese for himself, but the pope could retaliate in various ways, such as: ordering the local priests to not perform certain sacraments such as marriages, which would annoy the ruler's subjects; forgiving oaths made by the vassals to the ruler; and even excommunicating the ruler, thereby undermining his moral legitimacy. Eventually, the ruler would have to give in to the pope and accept a bishop. The longer a local ruler could hold out against the pope, the more leverage the ruler had to demand a bishop who suited his interests.
In a region where the pope's influence was weak, the local priests might have performed sacraments anyway, having calculated that defying the pope was not as dangerous as angering their parishioners; the ruler's vassals might have honored their oaths anyway because the pope could not protect them from their lord's wrath; and the subjects might still have respected their ruler despite excommunication.
If a diocese was prosperous and the pope's influence there was weak, the pope might give in to the local ruler and nominate a bishop who was loyal to the local ruler, because struggling with the local ruler over the appointment was not worth forfeiting the ample tax revenue. If a diocese was impoverished and the pope's influence was strong, the pope would stubbornly insist on nominating a bishop loyal to the pope, for the meager tax revenue of the diocese was not as valuable as having a loyal bishop in place.
A local secular ruler could stimulate the economy of his domain, and thereby collect more tax revenue, by giving his subjects more liberty and more participation in politics. Having more revenue strengthens the local ruler's grip on power because he can use the additional revenue to give greater rewards to his essential supporters and thereby strengthen their loyalty. On the other hand, liberalization and democratization weaken a ruler's grip on power because they make his subjects more assertive (see selectorate theory for a thorough explanation of these trade-offs). If the pope's influence over a region was strong, it was not worthwhile for the local ruler to risk liberalizing and democratizing his domain, for if the ruler kept the tax revenue all for himself (by rejecting the pope's nominee), the increased tax revenue would not be sufficient to counter-balance the risk of liberalization and the great risk of angering the pope; for the local ruler, oppressing his subjects was the more optimal strategy for political survival. If the pope's influence in the region was weak, it was worthwhile for the ruler to risk liberalizing and democratizing the region, because if the ruler kept the tax revenue all for himself (by rejecting the pope's nominee), the increased revenue would be more than sufficient to counter-balance the risk of liberalization and the small risk of angering the pope.
If a region was very prosperous and the pope's influence very weak, the ruler might feel confident enough to reject the pope's nominees for bishop indefinitely. This, Bueno de Mesquita argues, is what enabled the Protestant Reformation in northern Europe. The pope, who lived in Rome, had less influence in northern Europe because it is difficult in general to project power over long distances.
Science fiction writer Poul Anderson wrote the novel The Shield of Time, depicting two alternate history scenarios. In one, the imperial power completely and utterly defeated the Papacy, and in the other, the Papacy emerged victorious with the imperial power humbled and marginalized. Both end with a highly authoritarian and repressive 20th century that is completely devoid of democracy or civil rights. The conclusion stated by a protagonist is that the outcome in actual history (neither power gained a clear victory, with both continuing to counterbalance each other) was the best from the point of view of human liberty.
- History of the papacy (1048–1257)
- Cluniac Reforms
- First Council of the Lateran
- Petrus Crassus
- Charter of Liberties
- Statutes of Mortmain
- Quia Emptores
- Cestui que
- In his article "The Pactum Callixtinum: An Innovation in Papal Diplomacy", P. W. Browne observes that the term concordat was not in use until Nicolas of Cusa's De concordantia catholica of 1434.
- Cantor 1958, pp. 8–9.
- Rubenstein 2011, p. 18.
- Blumenthal 1988, pp. 34–36.
- Löffler 1910.
- Appleby, R. Scott (1999). "How the Pope Got His Political Muscle". U.S. Catholic. Vol. 64 no. 9. p. 36.
- Paravicini Bagliani, Agostino. "Sia fatta la mia volontà". Medioevo (143): 76.
- Henry IV 1076.
- Fuhrmann 1986, p. 64; Henry IV 1076.
- Floto 1891, p. 911.
- Pope Gregory VII 1076.
- Löffler 1910, p. 85.
- A. Creber, "Women at Canossa. The Role of Elite Women in the Reconciliation between Pope Gregory VII and Henry IV of Germany (January 1077)", Storicamente 13 (2017), article no. 13, pp. 1–44.
- Robinson, p. 195.
- Davis (1966), pp. 252, 253
- But see Joranson (1948), pp. 373–375
- Kohn, p. 210.
- Davis (1966), pp. 253–254
- Strayer (1959), pp. 215–216
- "Simple and radical": Norman F. Cantor, 1993. The Civilization of the Middle Ages p.262.
- Strayer (1959), p. 215
- Jordan (2003), p. 146
- Cantor 1993, p. 286.
- Metz 1960, p. 137.
- Attestatio nominis E. H. J. Münch: Vollständige Sammlung aller ältern und neuern Konkordate, vol. 1 (1830) p. 1 and p. 18
- Browne (1922)
- Hearder & Waley 1963.
- Dahmus (1969), p. 229
- Dahmus (1969), p. 320
- Dunham, S. A., A History of the Germanic Empire, Vol. I, 1835 p. 196
- Cantor 1993, p. 395.
- Davis (1966), p. 256
- Thorndike (1956), pp. 293–294
- Jordan (2003), p. 99
- Davis (1966), pp. 256, 257
- Cantor (1969), p. 303
- Bruce Bueno de Mesquita (December 2019). "The Game of Worms" (Speech). Duke University.