Investiture Controversy

Last updated

Myers, Philip Van Ness (1905), A medieval king investing a bishop with the symbols of office
.mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .id-lock-free a,.mw-parser-output .citation .cs1-lock-free a{background:url("//")no-repeat;background-position:right .1em center}.mw-parser-output .id-lock-limited a,.mw-parser-output .id-lock-registration a,.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("//")no-repeat;background-position:right .1em center}.mw-parser-output .id-lock-subscription a,.mw-parser-output .citation .cs1-lock-subscription a{background:url("//")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:url("//")no-repeat;background-position:right .1em center}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em} Investiturewoodcut.jpg
Myers, Philip Van Ness (1905), A medieval king investing a bishop with the symbols of office

The Investiture Controversy or Investiture Contest was a conflict between church and state in medieval Europe over the ability to install high church officials through investiture. [1] By undercutting imperial power, the controversy led to nearly 50 years of civil war in Germany. According to historian Norman Cantor, the Investiture Controversy was "the turning-point in medieval civilization", marking the end of the Early Middle Ages with the Germanic peoples' "final and decisive" acceptance of Christianity. More importantly, it set the stage for the religious and political system of the High Middle Ages. [1]


It began as a power struggle between Pope Gregory VII and Emperor Henry IV in 1076. [2] There was also a brief but significant investiture struggle between Pope Paschal II and King Henry I of England from 1103 to 1107. The conflict ended in 1122, when Pope Callixtus II and Emperor Henry V agreed on the Concordat of Worms, which differentiated between the royal and spiritual powers and gave the emperors a limited role in selecting bishops. The outcome was largely a papal victory, but the Emperor still retained considerable power.


In the 11th and 12th centuries, a series of popes challenged the authority of European monarchies about who had the authority to appoint ("invest") local church officials such as bishops of cities and abbots of monasteries.

After the decline of the Western Roman Empire, investiture was performed by members of the ruling nobility despite theoretically being a task of the church. [3] 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 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. [4] It was essential for a ruler or nobleman to appoint (or sell the office to) someone who would remain loyal. [3]

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.[ citation needed ]

Henry IV and Pope Gregory VII

The crisis began when supporters of the Gregorian Reform decided to rebel against simony by forcefully taking the power of investiture from the ruling secular power, the Holy Roman Emperor, and placing that power wholly within control of the church. The Gregorian reformers knew this would not be possible so long as the emperor maintained the ability to appoint the pope, so their first step was to forcibly gain the papacy from the control of the emperor.

When six-year-old Henry IV became King of the Germans in 1056, the reformers seized the papacy while the king was still a child. In 1059, a church council in Rome declared, with In nomine Domini , that leaders of the nobility would have no part in the selection of popes and created the College of Cardinals as a body of electors made up entirely of church officials. Having regained control of the election of the pope, the church was now ready to tackle investiture and simony.

In 1075, Pope Gregory VII composed the Dictatus papae . One clause asserted that the deposal of an emperor was under the sole power of the pope. [5] 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. [6] By this time, Henry IV was no longer a child, and he continued to appoint his own bishops. [5] 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". [7] 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. [8]

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. [9] In 1076 Gregory responded by excommunicating Henry, and deposed him as German king, [10] releasing all Christians from their oath of allegiance. [11]

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. [5]

Henry IV requests mediation from Matilda of Tuscany and abbot Hugh of Cluny. Hugo-v-cluny heinrich-iv mathilde-v-tuszien cod-vat-lat-4922 1115ad.jpg
Henry IV requests mediation from Matilda of Tuscany and abbot Hugh of Cluny.

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 to meet the pope and apologize in person. [12] 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 excommunicated Henry IV again.[ citation needed ]

Henry IV then proclaimed Antipope Clement III to be pope and Rudolf von Rheinfeld died in 1080, effectively ending the internal revolt against Henry. In 1081, Henry invaded Rome for the first time with the intent of forcibly removing Gregory VII and installing a friendlier pope. Gregory VII called on his allies, the Normans in southern Italy, and they rescued him from the Germans in 1085. The Normans sacked Rome in the process, and when the citizens of Rome rose up against Gregory, he was forced to flee south with the Normans. He died soon thereafter.

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. Henry IV was succeeded upon his death in 1106 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. Later, he renounced some of the rights of investiture with the Concordat of Worms, abandoned Gregory VIII, and was received back into communion and recognized as legitimate emperor as a result.

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." [13]

Concordat of London (1107)

Scale of justice, canon law.svg
Part of a series on the
Canon law of the
Catholic Church
046CupolaSPietro.jpg Catholicismportal

According to René Metz, author of What Is Canon Law?, a concordat is a convention 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. The concordat is one type of an international convention. Concordats began during the First Crusade's end in 1098. [14]

The Concordat of London (1107) suggested 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. Employing this distinction, Henry 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.

Concordat of Worms (1122)

On the European mainland, after 50 years of fighting, the Concordat of Worms provided a similar but longer-lasting compromise when it was signed on September 23, 1122.

It eliminated lay investiture, while allowing secular leaders some room for unofficial but significant influence in the appointment process. 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 the following:


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. [15]

On the other hand, 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.

However, the dispute did not end with the Concordat of Worms in 1122; future 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. [16] 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. [17]

Cultural references

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.

See also

Related Research Articles

Concordat of Worms agreement between Pope Calixtus II and Holy Roman Emperor Henry V on September 23, 1122 near the city of Worms

The Concordat of Worms is the 1122 agreement between Henry V, Holy Roman Emperor, and Pope Callixtus II, which brought to an end the first phase of the power struggle between the papacy and the Holy Roman Emperor, known as the Investiture Controversy. It was signed on 23 September, 1122, near the German city of Worms.

First Council of the Lateran Roman Catholic synod of 1123

The First Council of the Lateran was the 9th ecumenical council recognized by the Catholic Church. It was convoked by Pope Callixtus II in December 1122, immediately after the Concordat of Worms. The council sought to: (a) bring an end to the practice of the conferring of ecclesiastical benefices by people who were laymen; (b) free the election of bishops and abbots from secular influence; (c) clarify the separation of spiritual and temporal affairs; (d) re-establish the principle that spiritual authority resides solely in the Church; (e) abolish the claim of the emperors to influence papal elections.

Matilda of Tuscany Italian feudal margravine regnant of Tuscany

Matilda of Tuscany was a powerful feudal Margravine of Tuscany, ruler in northern Italy and the chief Italian supporter of Pope Gregory VII during the Investiture Controversy; in addition, she was one of the few medieval women to be remembered for her military accomplishments, thanks to which she was able to dominate all the territories north of the Papal States.

Pope Callixtus II Pope from 1119 to 1124

Pope Callixtus II or Callistus II, born Guy of Burgundy, was head of the Catholic Church and ruler of the Papal States from 1 February 1119 to his death in 1124. His pontificate was shaped by the Investiture Controversy, which he was able to settle through the Concordat of Worms in 1122.

The Salian dynasty was a dynasty in the High Middle Ages. The dynasty provided four German Kings (1024–1125), all of whom went on to be crowned Holy Roman Emperor (1027–1125); as such, the term Salic dynasty is also used to refer to the Holy Roman Empire of the time as a separate term.

Pope Gregory VII Pope

Pope Gregory VII, born Hildebrand of Sovana, was pope from 22 April 1073 to his death in 1085.

Pope Paschal II pope

Pope Paschal II, born Ranierius, was head of the Catholic Church and ruler of the Papal States from 13 August 1099 to his death in 1118.

Road to Canossa

The Road to Canossa, sometimes called the Walk to Canossa or Humiliation of Canossa, refers to Holy Roman Emperor Henry IV's trek to Canossa Castle, Italy, where Pope Gregory VII was staying as the guest of Margravine Matilda of Tuscany, at the height of the investiture controversy in January 1077 to seek absolution of his excommunication.

The Gregorian Reforms were a series of reforms initiated by Pope Gregory VII and the circle he formed in the papal curia, c. 1050–80, which dealt with the moral integrity and independence of the clergy. The reforms are considered to be named after Pope Gregory VII (1073–85), though he personally denied it and claimed his reforms, like his regnal name, honoured Pope Gregory I.

Antipope Clement III Antipope

Guibert or Wibert of Ravenna was an Italian prelate, archbishop of Ravenna, who was elected pope in 1080 in opposition to Pope Gregory VII and took the name Clement III. Gregory was the leader of the movement in the church which opposed the traditional claim of European monarchs to control ecclesiastical appointments, and this was opposed by supporters of monarchical rights led by the Holy Roman Emperor. This led to the conflict known as the Investiture Controversy. Gregory was felt by many to have gone too far when he excommunicated the Holy Roman Emperor Henry IV and supported a rival claimant as emperor, and in 1080 the pro-imperial Synod of Brixen pronounced that Gregory was deposed and replaced as pope by Guibert.

William I was bishop of Utrecht between 1054 and 1076. He was a typical representative of the German imperial system in which bishops were the main officials of the empire. He was a loyal follower of king Henry IV of Germany. William was appointed when a war was going on against West Frisia, which was resisting imperial authority. The imperial army conquered large parts of West Frisia in 1061, when Dirk V became count. King Henry gave the whole county to the bishopric of Utrecht in 1064. The whole of West Frisia was conquered in 1076 with the help of duke Godfrey III.

Blessed Gebhard von Salzburg, also occasionally known as Gebhard of Sussex, was Archbishop of Salzburg from 1060 until his death. He was one of the fiercest opponents of King Henry IV of Germany during the Investiture Controversy.

Burchard of Basle, also known as Burkart of Fenis, Burchard of Hasenburg or Burchard of Asuel, was a Bishop of Basel in the eleventh century and a supporter of Holy Roman Emperor Henry IV (1056–1106).

Hermann of Salm German anti-king

Herman(n) of Salm, also known as Herman(n) of Luxembourg, the progenitor of the House of Salm, was Count of Salm and elected German anti-king from 1081 until his death.

Synod of Worms

The Synod of Worms was an ecclesiastical synod and Imperial diet (Hoftag) convened by the German king and emperor-elect Henry IV on 24 January 1076, at Worms. It was intended to agree a condemnation of Pope Gregory VII, and Henry's success in achieving this outcome marked the beginning of the Investiture Controversy.

In nomine Domini is a papal bull written by Pope Nicholas II and a canon of the Council of Rome. The bull was issued on 13 April 1059 and caused major reforms in the system of papal election, most notably establishing the cardinal-bishops as the sole electors of the pope, with the consent of minor clergy.

Christianity in the 11th century Christianity-related events during the 11th century

Christianity in the 11th century is marked primarily by the Great Schism of the Church, which formally divided the State church of the Roman Empire into Eastern (Greek) and Western (Latin) branches.

History of the papacy (1048–1257)

The history of the papacy from 1048 to 1257 was marked by conflict between popes and the Holy Roman Emperor, most prominently the Investiture Controversy, a dispute over who— pope or emperor— could appoint bishops within the Empire. Henry IV's Walk to Canossa in 1077 to meet Pope Gregory VII (1073–85), although not dispositive within the context of the larger dispute, has become legendary. Although the emperor renounced any right to lay investiture in the Concordat of Worms (1122), the issue would flare up again.

Henry V, Holy Roman Emperor Holy Roman Emperor

Henry V was King of Germany and Holy Roman Emperor, the fourth and last ruler of the Salian dynasty. Henry's reign coincided with the final phase of the great Investiture Controversy, which had pitted pope against emperor. By the settlement of the Concordat of Worms with Pope Callixtus II he surrendered to the demands of the second generation of Gregorian reformers.

Benzo of Alba was an Italian bishop. He was an opponent of Gregorian reform who supported Henry IV of Germany in the Investiture Controversy.



  1. 1 2 Cantor 1958, pp. 8–9.
  2. Rubenstein 2011, p. 18.
  3. 1 2 Blumenthal 1988, pp. 34–36.
  4. Löffler 1910.
  5. 1 2 3 Appleby, R. Scott (1999). "How the Pope Got His Political Muscle". U.S. Catholic. Vol. 64 no. 9. p. 36.
  6. Paravicini Bagliani, Agostino. "Sia fatta la mia volontà". Medioevo (143): 76.
  7. Henry IV 1076.
  8. Fuhrmann 1986, p. 64; Henry IV 1076.
  9. Floto 1891, p. 911.
  10. Pope Gregory VII 1076.
  11. Löffler 1910, p. 85.
  12. 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.
  13. Cantor 1993, p. 286.
  14. Metz 1960, p. 137.
  15. Hearder & Waley 1963.
  16. Dunham, S. A., A History of the Germanic Empire, Vol. I, 1835 p. 196
  17. Cantor 1993, p. 395.


Primary sources

Henry IV, Holy Roman Emperor (1076). "Henry IV.'s Answer to Gregory VII., Jan. 24, 1076". In Henderson, Ernest F. (ed.). Select Historical Documents of the Middle Ages. Translated by Henderson, Ernest F. London: George Bell and Sons (published 1903). pp. 372–373. Retrieved 13 October 2017.
Pope Gregory VII (1076). "First Deposition and Banning of Henry IV. by Gregory VII., February 22, 1076". In Henderson, Ernest F. (ed.). Select Historical Documents of the Middle Ages. Translated by Henderson, Ernest F. London: George Bell and Sons (published 1903). pp. 376–377. Retrieved 13 October 2017.
Slocum, Kenneth, ed. (2010). "The Investiture Controversy". Sources in Medieval Culture and History. Boston: Prentice Hall. pp. 170–175. ISBN   978-0-13-615726-7.

Secondary and tertiary sources

  • Blumenthal, Uta-Renate (1988). The Investiture Controversy: Church and Monarchy from the Ninth to the Twelfth Century. University of Pennsylvania Press.
  • Cantor, Norman F. (1958). Church, Kingship, and Lay Investiture in England, 1089–1135. Princeton University Press.
  •  ———  (1993). The Civilization of the Middle Ages. HarperCollins.CS1 maint: extra punctuation (link)
Cowdrey, H. E. J. (1998). Pope Gregory VII, 1073–1085. Oxford University Press.
Floto (1891). "Gregory VII". In Schaff, Philip (ed.). Religious Encyclopedia: or Dictionary of Biblical, Historical, Doctrinal, and Practical Theology. 2 (3rd ed.). New York: Funk & Wagnalls Company. pp. 910–912. Retrieved 13 October 2017.
Fuhrmann, Horst (1986). Germany in the High Middle Ages c. 1050–1200. Translated by Reuter, Timothy. Cambridge, England: Cambridge University Press (published 2001). ISBN   978-0-521-31980-5.
Hearder, H.; Waley, D. P., eds. (1963). A Short History of Italy: From Classical Times to the Present Day.
Jolly, Karen Louise (1997). Tradition & Diversity: Christianity in a World Context to 1500. ME Sharpe.
Löffler, Klemens (1910). "Conflict of Investitures"  . In Herbermann, Charles (ed.). Catholic Encyclopedia . 8. New York: Robert Appleton Company. pp. 84–89.
McCarthy, T. J. H. (2014). Chronicles of the Investiture Contest: Frutolf of Michelsberg and His Continuators . Manchester: Manchester Medieval Sources. ISBN   978-0-7190-8470-6.
Metz, René (1960). What Is Canon Law?. The Twentieth Century Encyclopedia of Catholicism. 80. Translated by Derrick, Michael. New York: Hawthorn Books.
Morrison, Karl F., ed. (1971). The Investiture Controversy: Issues, Ideas, and Results. Holt McDougal.
Rubenstein, Jay (2011). Armies of Heaven: The First Crusade and the Quest for Apocalypse. New York: Basic Books. ISBN   978-0-465-01929-8.
Tellenbach, Gerd (1993). The Western Church from the Tenth to the Early Twelfth Century. Cambridge University Press.
Thompson, James Westfall; Johnson, Edgar Nathaniel (1937). An Introduction to Medieval Europe, 300–1500.

Further reading

Primary sources

Halsall, Paul, ed. (2007). "Selected Sources: Empire and Papacy". Internet Medieval Sourcebook. New York: Fordham University. Retrieved 13 October 2017.
Henderson, Ernest F., ed. (1122). "Concordat of Worms, Sept. 23, 1122". Select Historical Documents of the Middle Ages. Translated by Henderson, Ernest F. London: George Bell and Sons (published 1903). pp. 408–409. Retrieved 13 October 2017.
Pope Gregory VII (1078). "Decree of Nov. 19th, 1078, Forbidding Lay Investiture". In Henderson, Ernest F. (ed.). Select Historical Documents of the Middle Ages. Translated by Henderson, Ernest F. London: George Bell and Sons (published 1903). p. 365. Retrieved 13 October 2017.
 ———  (1080). "Second Banning and Dethronement of Henry IV., through Gregory VII., March 7th, 1080". In Henderson, Ernest F. (ed.). Select Historical Documents of the Middle Ages. Translated by Henderson, Ernest F. London: George Bell and Sons (published 1903). pp. 388–391. Retrieved 13 October 2017.CS1 maint: extra punctuation (link)
 ———  (1903). "The Dictate of the Pope". In Henderson, Ernest F. (ed.). Select Historical Documents of the Middle Ages. Translated by Henderson, Ernest F. London: George Bell and Sons. pp. 366–367. Retrieved 13 October 2017.CS1 maint: extra punctuation (link)

Secondary and tertiary sources

Blumenthal, Uta-Renate (2016). "Investiture Controversy". Encyclopædia Britannica . Retrieved 13 October 2017.
"Investiture". The Columbia Encyclopedia (6th ed.). New York: Columbia University Press. 2007. Archived from the original on 21 February 2009. Retrieved 13 October 2017.
Nelson, Lynn H. "The Owl, the Cat, and the Investiture Controversy". Lectures for a Medieval Survey. On-line Reference Book for Medieval Studies. Archived from the original on 15 February 2015. Retrieved 13 October 2017.
Schroeder, H. J. (1937). "The Ninth General Council (1123)". Disciplinary Decrees of the General Councils: Text, Translation, and Commentary. St. Louis, Missouri: B. Herder Book Co. pp. 177–194. Retrieved 13 October 2017.
Van Hove, Alphonse (1910). "Canonical Investiture"  . In Herbermann, Charles (ed.). Catholic Encyclopedia . 8. New York: Robert Appleton Company. p. 84.