Gero cross
The Gero (also: Gerokruzifix ) in Cologne Cathedral is one of the oldest large crucifixes in Europe north of the Alps. The 2.88 m high oak cross dates from the Ottonian period towards the end of the 10th century and is one of the first monumental sculptures of the Middle Ages. In the history of occidental iconography it is an example of the turning point in the representation of the Christian Redeemer, who - previously usually heroically and victoriously depicted in an upright position - is shown suffering and human for the first time. The sculpture is therefore considered a model for many of the following depictions of Christ from the Middle Ages.
history
Emergence
The presumed client of the Gero Cross is the Archbishop of Cologne, Gero . In 971 he traveled to Constantinople (today's Istanbul) on behalf of Emperor Otto I to find a daughter of the Eastern Roman Emperor as a bride for the Emperor's son Otto, who later became Emperor Otto II . After lengthy negotiations, he finally brought the twelve-year-old imperial niece Theophanu with him to the Holy Roman Empire as his bride . She had numerous artists and craftsmen in her wake, who contributed to the growing influence of Byzantine art in the empire - although Gero himself got to know the art there well during his long stay in Constantinople and could have exercised his influence on the design of the cross.
The cross was made by an unknown artist in the second half of the 10th century. Due to the origin of the wood, it is certain that it was made in Cologne or the surrounding area. The cross was placed in the Old Cathedral (also Hildebold Cathedral ), the precursor church of today's Cologne Cathedral, in the middle of the nave on the sarcophagus of its founder Gero.
The chronicler Thietmar von Merseburg reported in his chronicle at the beginning of the 11th century of the cross and a related miracle of the Gero, which is said to have made a crack in the head of the sculpture disappear by inserting a consecrated host and a relic splinter and fervent prayer:
“The wooden Crucifixus, which now stands in the middle of the church above his grave, he [Gero] had skillfully made. But when he noticed a crack in his head, he healed it without intervention of the highest artist, so much more healing. He united a part of the body of the Lord, our only consolation in every need, with a part of the saving cross, placed it in the gap, prostrated himself and implored the name of the Lord; when he got up again, he had brought about the healing through his humble praise. "
Later mentions and events
After the foundation stone for the new Gothic cathedral was laid in August 1248 , the old Carolingian cathedral burned down completely during the demolition work. The Gero cross survived the fire and has been placed in the chapel wreath of the new church building since 1270, probably above the altar of the St. Stephen's Chapel , where the Gero sarcophagus is still located today .
In 1351 at the latest, the cross was moved to the east wall of the Kreuzkapelle, where it still hangs today. This is evidenced by a deed of foundation in which the Holy Cross Brotherhood, founded by the tailors' guild, donated a candle bar ("tailor bar") to the cathedral, which still hangs in front of the Kreuzkapelle today; we are talking about ante introitum chori versus altare s. crucis , a few decades later it says about this event:
“Wilche broiderschaft haint sij made and donated in the ere of the almighty goitz and the holy cruizes, also granted, that see a bar with vunf candles by the holy cruz altair. [...] before the holy sacrament, dat there stands in the houfde of holy crutz in the dome ... "
The Gero cross is also mentioned in the Vita of Irmgard von Süchteln from the 14th century; the legend reports that during her third pilgrimage to Rome a cross spoke to her in a church there and said "greetings" to the Gero cross in Cologne. Here, too, there is talk of the cross ... in ecclesia S. Petri prope sacristiam or later in a translation of ... in St. Peterskirchen zu Collen vur der gherkammere , that is, of a location in front of the sacristy ; the entrance to the sacristy is on the north wall of the Kreuzkapelle.
The baroque altar surrounding the cross, designed according to the Roman model, and the golden halo ( mandorla ) with alternating rays were donated in 1683 by canon Heinrich Friedrich von Mering , who was responsible for the design of the cathedral choir. The altar received a Latin inscription:
“The human nature of our crucified Lord Jesus Christ. May our understanding, enlightened by the Spirit of Truth, receive with a pure and free heart the glory of the Cross (Pope Leo), which shines over heaven and earth. Who suffered for us through your holy wounds, the price of our salvation, have mercy on us, Lord, have mercy on us. Sure and certain is the expectation of the promised bliss where there is participation in the suffering of the Lord (Pope Leo). Heinrich Mering, senior presbyter, canon and capitular, designed and built (this altar). "
At this point in time, the cross was fixed in a holder for the first time, previously it was probably free, with a few fixings, leaning against the altar wall.
The last comprehensive processing of the cross was carried out in 1900 by Wilhelm Batzem; from a modern restoration point of view, it did some damage.
Description and state of restoration
The description is based, among other things, on an investigation report by Christa Schulze-Senger and Bernhard Matthäi from 1976.
Body
The body (crucifixus) is 1.87 meters high from head to feet, and exactly two meters from the suppedaneum to the top of the hand. The span is 1.66 meters, and at the head the sculpture reaches its maximum depth of 33 centimeters. It is made from a high quality oak log ; The fresh wood was probably roughly preformed and later, after a drying and storage phase, carved into its final, finely worked shape in order to prevent cracks.
The wooden surface is very carefully smoothed so that there are almost no traces of machining or tools to be seen on the outside. Apparently, some contours on the fingers and beard were later reworked with sharper tools. The skin surface contains at least seven layers of paint ( incarnates ). The last one from 1900 has almost disappeared; the lowest - probably original - layer is best preserved. Most of the damage to the earlier incarnates comes from the Batzem treatment in 1900. Overall, the layers of paint on the frame are so thin that the sculpture is not disfigured. Only in the loincloth is the last, very thick, coarse layer of gold likely to distort the original texture.
The body is hollowed out from the rear and therefore only weighs 36.5 kilograms. It is possible that the cavity was previously filled with a mixture of canvas and glue; it can only be seen by removing the body from the cross and shows the rough but neatly carved traces of simple tools.
The arms are attached and attached to the body with wooden dowels.
The life-size figure of Christ is shown with closed eyes, bulging belly, sunken chest and sinews protruding from arms and legs. The thumbs on the nail-pierced hands hang down. The dark to deep brown shoulder-length hair of the sculpture is very finely chiseled at the front and arranged very generously across. The head does contain a drilled hole and a few nails at the back of an unexplained purpose, but demonstrably no crack or hidden cavity for relics , as had been assumed to be certain in the literature up to the investigation of 1976 (Haussherr, Imdahl et al.).
The loincloth is gilded on the outside and painted red on the inside; underlying layers were largely washed off here. It is possible that it was red in the original, which in combination with a gold-studded cross may have had a completely different effect.
The feet stand on the suppedaneum and are each nailed to the cross with a nail, which is typical of the so-called four-point phase in Christian iconography (in the three-point phase, both feet are pierced with one nail). Two toes are missing on the left foot due to breakage and / or weathering, and the big toe on the right foot. The heels are badly weathered at the back. Otherwise, the sculpture is well preserved for its age.
cross
The two oak boards that make up the crucifix are about 40 cm wide and 4.3 to 4.7 cm thick on average. The longitudinal beam measures 2.88 meters, the transverse beam 1.98 meters. The upper end merges into the titulus at a height of 20 centimeters , a 49 centimeter wide field with the inscription I · N · R · I in black Gothic minuscules . At the lower end of the longitudinal beam (probably around 1683) a shaft was cut out at a height of three centimeters in order to place the cross in a holder.
The transverse and longitudinal bars are covered with leaves in the upper third of the longitudinal bar; The crossbeam was first attached with five wooden nails. Later, four iron nails and eight metal staples - almost no longer available today - were added. There are two eyebolts on the crossbar, which presumably were used to cover the cross during Lent.
The front of the cross was gilded during the last major processing by Wilhelm Batzem in 1900. Numerous small nails in the cross indicate that gold sheet metal fittings may previously have existed. The back is painted brown.
At the intersection of the longitudinal and transverse beams there is a round relief with a diameter of 50.5 cm, presumably carved from walnut wood, which depicts the halo ( nimbus ) of the crucified. The six-centimeter-thick relief is divided into four fields by an isosceles cross, which in turn are provided with four teardrop-shaped hollows. On the outer edge of the relief and on the cross, alternating red and green rock crystals are attached as decoration; the largest of them is in the middle, it was probably made from a knob or something similar, which together with the fan-shaped design suggests that the halo was not part of the original decoration of the cross. It probably dates from the 12th century.
Dating
Art historical dating
In terms of art history, the connection between the Gero legends and the cross was no longer present in the 19th century; For example, the restorer Wilhelm Batzem painted over the altar painting in the Stephanus chapel (see photo) with a central arch in such a way that it was no longer clear that the cross had once stood in the middle of the picture in front of the empty red area.
It was not until 1924 and 1930 that Richard Hamann drew style comparisons with various Ottonian sculptures, including the precisely dated Bernward door of Hildesheim Cathedral from 1015, and in two works he again related the Thietmar description to the Cologne cross. Hamann's early dating to the 10th century was a breakthrough for the history of art, which until then had assigned the Gero cross to the 12th century (among others in Beenken).
The light blue background surface of the altar dates from 1976; Paul Clemen described it as red in 1937.
Dendrochronological dating 1976
In 1976 the cross was removed for the restoration of the baroque altar; the corpus was detached from the cross for a comprehensive examination and conservation and could thus also be described in detail from the back for the first time. Contrary to the initial concerns of the state curator and other experts who feared damage to the work of art, a dendrochronological examination was carried out on this occasion not only on the cross but also on the body , which essentially confirms the early dating to the end of the 10th century.
The dendrochronologist Ernst Hollstein (1918–1988) from the Rheinisches Landesmuseum Trier carried out an examination of the cross and body in order to obtain a more precise dating. For this purpose, he was able to measure 209 successive annual rings on the upper edge of the cross very precisely and make measurements and usable estimates on the corpus using annual ring counts at various points. In a regional diagnosis, he was also able to narrow down the growth region of the oaks used to the area of the Archdiocese of Cologne - it is very likely that the wood comes from the northern Eifel , but it cannot be entirely ruled out that it originated in the area around Wiedenbrück .
Examination of the Cross
Examination of the cross revealed that the oak was around 250 years old when it was felled. The starting point for the dating was the established fact that the cross existed at the latest in 1683 and the assumption that it was made around 800 at the earliest. A significant correspondence of the 209 annual rings with the West German oak chronology was measured for the years from 757 to 965. Hollstein assumed, based on his experience, that when the cross was made, not much more than the unusable sapwood was removed from the oak trunk; the felling of the tree therefore certainly fell between 971 and 1012. This was a significant result, as art historians had dated the cross to a much later period, with a long time having passed between the date of the felling and the production of the cross can.
Examination of the corpus
The examination of the sculpture turned out to be more complicated, since for restoration reasons one could neither take samples nor measure such a high number of connected annual rings as with the cross. Exact values were only obtained for the annual rings between 647 and 779, further annual ring sequences were measured and estimated from photos. The oak's growth phase therefore began around 570; the tree was about 400 years old. Hollstein estimated the outermost part of the carved body at the top of the head on the basis of these findings to the year 940. Here, too, he assumed with high probability and from experience that only the outer sapwood annual rings, which lasted about 25 years, were removed and not essential more was wasted on high quality heartwood ; this results in a precipitation time around the year 965. Due to the above-mentioned restrictions in the investigation, Hollstein estimates the dating of the sculpture to be less reliable than that of the cross, but considers it to be "probable" from a scientific perspective.
Art historical assessment and discussion of the investigation
The art-historical résumé of Rolf Lauer following the dendrochronological investigation takes up the scientific results and sees them as a renewed confirmation of the early dating of the Gero cross. Most authors have followed this view up to the present day. In contrast, there is the work of the Cologne art historian Günther Binding from 1982, who raises considerable doubts about the conclusions of the study and advocates dating it to the last decade of the 10th century. Binding states that there were two different crosses in the old cathedral and that it can no longer be clarified today which one is being referred to in the historical sources. The lack of a reliquary repository speaks against an identity with the original cross donated by Gero . In terms of art history, there was a stylistically closed group of works of art at the turn of the first millennium, including the Lothar cross and the Gereon sacramentary, in which the Gero cross fits seamlessly. In addition, it can by no means be assumed for certain that only the sapwood was removed from the tree trunk in order to make the sculpture. From these further arguments, Binding dates the “so-called Gero crucifix” to the term of office of Archbishop Everger , who also founded the Ottonian Cologne School of Painting and commissioned several other significant works of art.
Most of the more recent works on the Gerokreuz and its surroundings do not follow Binding's interpretation or explicitly contradict it as "not convincing". The authors of an article from 2008, which deals with investigations on a number of sculptures in eastern Germany, criticize Holstein's conclusions from a dendrochronological point of view as inaccurate. Although they do not rule out early dating, they agree with Binding's methodological criticism and recommend further examinations using modern means, such as computed tomography or other non-destructive methods.
Art historical and iconographic classification
Influences
After the art-historical dating of the Gero Cross, which took place relatively late in the second half of the 10th century, the question has repeatedly been asked of the influences under which this work of Ottonian art was created. A derivation of type and style to contemporary local traditions was considered impossible due to the lack of preserved objects. Sacred monumental sculptures, especially figures of saints, from the pre-Ottonian period are described in historical sources, but most of them have not survived; the Golden Madonna of Essen is an exception . Smaller sculptures, such as Carolingian ivory carvings, were therefore mostly used for typological and stylistic comparisons.
The precise anatomical representation of the figure of Christ is a focal point in the reception of art history: the arms are tense, the weight of the hanging body pulls them down and the tendons and muscles protrude. Pelvic bones stand out, the chest is depressed and the rib cage emerges. The feet are nailed separately to the suppedaneum . The resulting counter-pressure from below causes the upper body to sag to the left, as do the legs, buckled at the knees. This tense contrapostic posture (Haedeke) with standing and free leg finds the greatest lateral deflection (ponderation) in the hip area. The sculpture depicts Christ at the moment of his death with “strong effects”.
If one compares this posture with the existing Carolingian small sculptures, the type elements described can hardly be detected and only hinted at again. Vorottonian crucifixes depict Christ as the radiant victor - he stands or "floats" upright and with open eyes on the cross. An example of this is the Gisela cross , which was made in 1006 and is now in the treasury of the Munich residence . Due to this obvious difference in the posture of the Christ figure of the Gero Cross to previous western crucifixes, a strong Byzantine influence was assumed for a long time - first by Albert Boeckler.
Examples of similar, Byzantine-influenced works were the sacramentary from St. Gereon (now in the French National Library in Paris ) or the Aachen cross of Lothar ; however, these are from a later time.
The stylistic differences between the Gero cross and the few surviving Byzantine depictions of Christ are nevertheless described as too clear to accept Byzantium as a fixed and sole model. Similarities can be found in the details, for example in the asymmetrical arrangement of the loincloth, which is also found in a Byzantine ivory sculpture from the 8th century ( Metropolitan Museum New York). If, however, the focus of the Gero Cross is primarily on the painful, suffering person, in Byzantine sculptures one finds a Christ rather than the quiet, noble sufferer of all suffering. These figures are also softer and more flowing in shape and form a pondered Byzantine type .
In summary, various stylistic and theological influences are ascribed to the Gero cross, right up to the complete negation of the Byzantine models (in Kröger). Haedeke has already assigned the iconographic details to five different directions: the painterly style and the asymmetrical loincloth are typically early Byzantine, the sharpness and clarity of the garment depiction is due to the severity of the Central Byzantine Romanos group , while the classic posture is based on ancient models. "Late antique illusionism" can be found in the chiseled design of the hair. But this classification also interprets the most important characteristic of the Gero Cross as new and occidental: the hard, ascetic expressiveness, the tension and straining of the arms, the physical pain is not to be found in Byzantium either. There, figures of Christ are either dignified and representative or characterized in their suffering by "beautiful painfulness". Haussherr also shows stylistic parallels to crucifix images in French-Maasland areas (e.g. Reims ), as they still appeared in Carolingian times.
Other crucifixes of the time
As described, there is no real continuity in the depiction of Christ crucified from the 10th to the 12th centuries, which makes dating individual pieces difficult. Style and type comparisons are therefore mostly limited to details. When dealing with the Gero cross, comparisons are made with the surviving crucifixes from the 11th and 12th centuries, including the Georg crucifix restored in Cologne in 2003 or the Minden Cross . A monumental cross kept in the village church of the Upper Bavarian town of Schaftlach (Gmd. Waakirchen ) is dated around 1020; the Enghausen cross in the Bavarian district of Freising was backdated after a restoration in 2006 to around 890/900. The Gerresheimer crucifix in the Basilica of St. Margareta should also be mentioned .
Torso of the Georg crucifix (around 1067), with a similarly swelling body shape and traits of suffering. Cologne, Museum Schnütgen (Inv.-No. A 9)
The eyes of the crucified one are closed. Georg crucifix, Cologne, Museum Schnütgen (Inv.No. A 9)
The Minden Bronze Cross (1170/1020): Christ with open eyes, standing rather than hanging, without a wound on the side, but with signs of suffering, sunken chest and drawn down corners of the mouth.
The possible creator of the Minden cross, Rogerus von Helmarshausen , may have known the Gero cross from his work in Cologne.
Alternative theories of origin
In a work from 1989 Wilhelm Jordan put forward the thesis that the Gero cross was designed after the Turin shroud or a parchment copy of it. He assumes that the cloth, which can be proven to have been transferred from Edessa to Constantinople in 944, was the Turin burial liner and that Archbishop Gero was therefore able to see it during his stay in Constantinople. The 1988 radiocarbon analysis, which dates the Turin Shroud to the 14th century, questioned Jordan as questionable.
Jordan stated that Gero had brought a copy of the shroud on parchment with him to Cologne and had commissioned an artist to make the sculpture based on this template. The passage from the Thietmar Chronicle ex ligno studiose fabricari precepit. - “[The cross] he had [Gero] made skillfully.” He translates alternatively as “he had it made with care” , ie exactly according to the (model) image of the cloth. A number of similarities between the cloth and the Christ sculpture of the Gero cross should not be regarded as coincidental, such as the almost exactly matching size, the similarity of the face, an “asymmetry in relation to the stronger or swollen left cheek” and an anomaly in the right ear .
The reception of this theory is rather low among theologians and art scholars. An influence of the image on the Turin shroud on later depictions of Christ cannot be ruled out, but it cannot be scientifically proven that the creation of the Gero cross is directly related to the cloth in Constantinople.
Theological Aspects
In addition to the iconographic details described, the fact that the dead Christ is shown on the Gero cross plays a particularly important role in the interpretation . The hanging - not standing - on the cross, the closed eyes and the proof of death mentioned in the Gospel of John (19:34) by the lance stab in the right side of the body are indicative of this.
Old Christian, early Byzantine depictions depict the wound on the side, but on a crucified with wide open eyes, on the cross “standing or floating” (landlord). In the West, however, the type of living triumphant on the cross prevailed. The causes for such a clear development of iconography cannot be viewed independently of theological dogmas and developments in faith.
Since no revolutionary changes in dogma are known in the early Middle Ages (such as Christology ), the theological interpretation is more likely to assume a change in the Western image of Christ within the given dogmas. The time of origin of the Gero cross lay exactly between the patristic and the beginning of the scholastic . For the whole of the West, however, influences from the Cluny movement can be assumed, which placed the crucified at the center of religious thought (Kröger).
If one does not completely reject the possible Byzantine influence on the Gero Cross, the dispute over images of the Eastern Church in the 7th and 8th centuries could also have played a role in the altered representation of Christ. The very human nature of Christ, which includes mortality and death, was considered by the iconodules - the defenders of images - as an argument in favor of a pictorial representation of the Savior.
As an example of the piety on the cross of the period under review, the house owner cites a collection of prayer by Petrus Damiani , in which on the one hand the Passion of Christ is celebrated as victory over "sin, death and the devil", but on the other hand the sacrificial character of the death on the cross, humility and vulnerability of the crucified was worked out. The theological views on the character of the death on the cross vary in the period under consideration, as does the artistic depiction of the cross during this time. Many views existed in parallel until the 12th century.
Further evidence for the religious background of the medieval depictions of the crucifixion can be found in Jonas von Orléans and Bernhard von Angers , who both also emphasize the sacrifice, the most important aspect of the Catholic Eucharistic celebration : in the sacrifice of the Mass, the sacrifice of the cross for the forgiveness of sins is visualized.
For the Carolingian sphere of influence of the 8th and 9th centuries, the Libri Carolini document the prevailing belief in the cross; here we speak of the “banner, sign of our victor” - so the divinity of Christ is also emphasized. However, as early as the beginning of the 9th century, the sacrament, mass and the Eucharist emerged as religious centers. The change in the visual representation of crucifixes can also be interpreted from this shift in meaning: blood from the side wound corresponds to the blood of the measuring sacrifice; The suffering and death of the incarnate God, “the ultimate salvation” are illustrated and made comprehensible.
This theological image of the Gero cross is further elaborated in later important works, for example by Bernhard von Clairvaux or Anselm von Canterbury - Bernhard places the person Jesus at the center of faith, Anselm emphasizes above all the redemption of humanity through the death of the "God Man" on the cross. .
See also
literature
- Hermann Beenken : Romanesque sculpture in Germany (11th and 12th centuries) . Klinkhardt & Biermann, Leipzig 1924, pp. 214f.
- Hanns-Ulrich Haedeke: The Gero Cross in Cologne Cathedral and its successor in the 11th century , in: Kölner Domblatt 14–15 (1958), p. 42 ff.
- Reiner Haussherr : The dead Christ on the cross. On the iconography of the Gero cross . Dissertation, University of Bonn 1963.
- Max Imdahl: The Gero Cross in Cologne Cathedral . (= Work monographs on the fine arts in Reclam's universal library; B 9097). Reclam, Stuttgart 1964.
- Rudolf Wesenberg: Early medieval sculptures. The school of Rhenish sculpture and its charisma . Schwann, Düsseldorf 1972, ISBN 3-508-00179-2 .
- Günther Binding: The dating of the so-called Gero crucifix in Cologne Cathedral. in: Egon Boshof (Ed.), Archive for Cultural History, Volume 64, Issue 1, Böhlau Verlag, Cologne / Vienna.
- Wilhelm Jordan: The Gerokreuz in Cologne and the Turin grave linnen. New discoveries . Queckenberg, 1989.
- Christa Schulze-Senger, Bernhard Matthäi, Ernst Holstein, Rolf Lauer: The Gero Cross in Cologne Cathedral. Results of the restoration and dendrochronological investigation in 1976 , in: Yearbook of Rheinische Denkmalpflege, 32, 1987, pp. 11–54.
- Ludwig Kröger: The Gero Cross in Cologne Cathedral and its teaching of faith didactics . Diploma thesis, University of Bonn 1989 (copy: Archbishop's Diocesan and Cathedral Library Cologne).
- Bruno Klein: The Gero Cross. Revolution and limits of figurative mimesis in the 10th century , in: Bruno Klein, Harald Wolter-von dem Knesebeck (ed.), Nobilis Arte Manus. Festschrift for the 70th birthday of Antje Middeldorf Kosegarten . Self-published by Bruno Klein, Dresden 2002, ISBN 3-00-009205-6 , pp. 43–60.
- Manuela Beer: Ottonian and early Salian monumental sculpture. Development, form and function of wood sculptures of the 10th and early 11th centuries. in: Klaus Gereon Beuckers , Johannes Cramer, Michael Imhof (eds.), Die Ottonen. Art - Architecture - History , 2002, ISBN 3-93-252691-0 , pp. 129–152.
- Günther Binding: Once again on the dating of the so-called Gero Cross in Cologne Cathedral. In: Wallraf-Richartz-Jahrbuch. 64/2003, pp. 321-328. online version (PDF; 122 kB)
- Tilo Schöfbeck, Karl-Uwe Heussner: Dendrochronological investigations on medieval works of art between the Elbe and Oder. in: Peter Knüvener, Adam Labuda and Dirk Schumann (eds.), Tradition - Transformation - Innovation. The visual arts of the Middle Ages in the Mark Brandenburg. P. Knüvener, A. Labuda and D. Schumann, Lukas Verlag, Berlin 2008, pp. 172-187.
Web links
Remarks
- ^ Paul Clemen : The art monuments of the city of Cologne. Cologne Cathedral 1938, p. 243
- ↑ Christa Schulze-Senger, Bernhard Matthäi, Ernst Holstein, Rolf Lauer: The Gero Cross in Cologne Cathedral. Results of the restoration and dendrochronological investigation in 1976, in: Yearbook of Rhenish Monument Preservation, 32, 1987, p. 42.
- ↑ Bruno Klein: The Gero Cross. Revolution and limits of figurative mimesis in the 10th century , in: Bruno Klein, Harald Wolter-von dem Knesebeck (ed.), Nobilis Arte Manus. Festschrift for the 70th birthday of Antje Middeldorf Kosegarten . Self-published by Bruno Klein, Dresden 2002, ISBN 3-00-009205-6 , p. 56, end note 1
- ↑ Manuela Beer: Ottonian and early Salian monumental sculpture. Development, form and function of wood sculptures of the 10th and early 11th centuries. in: Klaus Gereon Beuckers , Johannes Cramer, Michael Imhof (eds.), Die Ottonen. Art - Architecture - History , 2002, ISBN 3-93-252691-0 , p. 136, footnote 53
- ↑ Tilo Schöfbeck, Karl-Uwe Heußner: Dendrochronological studies of medieval works of art between the Elbe and Oder. in: Peter Knüvener, Adam Labuda and Dirk Schumann (eds.), Tradition - Transformation - Innovation. The visual arts of the Middle Ages in the Mark Brandenburg. P. Knüvener, A. Labuda and D. Schumann, Lukas Verlag, Berlin 2008, p. 186.
- ↑ Hanns-Ulrich Haedeke: The Gero Cross in Cologne Cathedral and its successor in the 11th century , in: Kölner Domblatt 14-15 (1958), p. 42 ff.
- ↑ Ludwig Kröger: The Gero Cross in Cologne Cathedral and its didactic teaching . Diploma thesis, University of Bonn 1989 (copy: Archbishop's Diocesan and Cathedral Library Cologne )
- ↑ Bavaria has the oldest monumental life-size crucifix ( memento from April 24, 2008 in the Internet Archive )
