The following essay is based on a paper discussed at the workshop "Courtly Culture Outside the Court," 28-31 December 2003, at the Ben-Gurion University of the Negev (Israel) and reflects aspects of my work on the Legend of the True Cross.
By Barbara Baert
Catholic University of Leuven, Belgium
History of Art Department
There must have been a time when people were so fascinated by the wood of Christ’s cross that the longing to see it, to touch it, even to kiss it consumed them completely. It was the time when Christianity had cautiously begun to emerge from its struggle for recognition and the religion’s expansion was outwardly manifested in new places of worship from Rome to Constantinople, from Jerusalem to Edessa. And it was at that time, so it is told, that a single Jew and a Christian queen dug deep into the earth and found that which people yearned to find: the True Cross.
The research of the legend of the True Cross encompasses relic cults, pilgrimages, travelers' tales, and the Tree of Life; it involves Church Fathers, crusader kings, Teutonic Knights, and mendicant orders, all of which influenced the legend's depiction from its earliest representation in manuscripts, reliquaries, and altarpieces, to the great monumental cycles of the high Middle Ages. If the holy wood were the medium of medieval memory, the Legend of the True Cross reveals the growth rings of fifteen centuries of imagery.
In this paper, I want to focus on one peculiar theme. According to the Legend of the True Cross, the Byzantine emperor Heraclius (610-641) was involved in a battle against Chosroes II (588-628?), the Sassanian king who had stolen the cross in Jerusalem. Entering the astrological tower in Ctesiphon, Heraclius finds Chosroes sitting at his mechanical throne. It was kept in constant movement by horses, just as the universe is constantly moving. Into the throne, Chosroes had placed the cross relic "as the sun," and an image of a cock "as the ghost." Chosroes considered himself "as the father." Heraclius decapitates Chosroes on his throne and restitutes the cross to Jerusalem. This event, the Restitutio crucis, is remembered during the so-called feast of the Exultation of the Cross at September 14th.
I will explore the tradition of the Restitutio crucis in the historical, liturgical, and iconographical sources.
Already in his own lifetime a complex of legends was generated around Heraclius. He was renowned for his series of victories over the Persians, who threatened the Greek-speaking part of the Roman Empire at the beginning of the seventh century and who, moreover, had plundered the Church of the Holy Sepulcher in Jerusalem. The legend of the Restitution of the Cross is part of a broad cultural platform. Indeed, the figure of Heraclius is shared not only by Persians and Christians but also by Jews and Arabs as well. Because all these different cultures appropriated the stories, the legend developed in an erratic way. The religious-cultural implications of the conflict between the Greeks and the Persians were so profound that they were described in eschatological and apocalyptic terms.
The events had an enormous impact on the Christian empire of that time – and on the "heathen" world beyond. Not only were geographic borders the stake in political shifts but also the various worldviews concerned. In his Expeditio Persica (622) and Heraclias (628),  Georgios Pisides, deacon of Hagia Sophia in the time of the patriarch Sergius, depicted the events as a horrible nightmare, an apocalyptic peril. Theophanes (765-817, Chronographia) described Heraclius as a mythic hero, who only by his great perseverance had been able to force the empire of Chosroes to yield.  In an early seventh-century source from Edessa, Heraclius is even compared with Alexander the Great.  In the same period, Antiochus Stratedus describes the taking of Jerusalem by Chosroes with evangelical references to Christ’s Passion,  while the anonymous Jewish writer of the Dream of Zerubbabel regards the Sassanian incursions as a Messianic liberation from the "betrayer" Heraclius. 
Historians suppose that the campaigns of Heraclius took place in the years between 622-628 and that Heraclius did indeed restore the relic of the True Cross (preserved in the Church of the Holy Sepulcher since Helena found it and it was subsequently stolen by the Persians) to its original place in Jerusalem. It was mentioned in both contemporary and near-contemporary sources in the Byzantine world, such as Georgios Pisides’ In Restitutionem S. Crucis.  In that source, it was said that Patriarch Modestos examined the relic and proclaimed it intact. It was preserved in a sealed container. Of course, it is hard to reconstruct the historical truth from these chronicles to know whether the restitution of a relic of the Cross really took place and how and when. This is not the place to dwell on this; however, historians nowadays agree on the factual restitution of a cross in a great ceremony on 21 March 630. I refer to the recent study by Walter Kaegi (2003).  An ironic detail occurs in this history: the eastern parts of the empire proved unable to withstand new Persian invasions and the rapid Arab expansion following the death of Muhammad (570-632).  Heraclius could do little but look on; a few years later, from 634, the areas he had freed from the Persians fell into the hands of the Arab Caliph Omar and subsequently converted to Islam.  In 635, the Cross he had restored to Jerusalem was brought for safekeeping to Constantinople and was subsequently lost to history. 
Already in the seventh century the restoration of the Cross was celebrated in Constantinople on 14 September, Holy Cross Day.  The feast gained a firm foothold in western Europe and became extremely popular due to the eighth-century homily Reversio sanctae atque gloriosissimae cuicis Domini nostri Jesu Christi. The text was edited by Migne under Hrabanus Maurus (780-856),  archbishop of Mainz (847) and abbot of the monastery school of Fulda, although today this authorship is contested. The Swedish theologian and philologist Stephan Borgehammar is currently preparing the critical edition of the Reversio sanctae crucis for the acta bollandiana and does not believe Hrabanus Maurus was the head of the stemma. 
The author of the Reversio specifies that the Byzantine emperor beheaded Chosroes II in his tower palace. Chosroes had built a tower in which he installed images of the sun, the moon and the stars for what is called "occult" purposes. As if he were God himself, Chosroes could watch from above how the rain streamed earthwards. Deep in a cellar, horses kept the tower in constant motion, like the heavenly bodies themselves. Chosroes had placed the stolen Cross beside him.
Heraclius defeats Chosroes’ son on a bridge over the Danube.  Chosroes’ son accepts baptism and destroys the blasphemous throne His triumph complete, Heraclius returns to Jerusalem with the Cross and makes his way down the slopes of the Mount of Olives to the gate by which Christ entered the city at the start of His Passion; there he is greeted with lanterns and palm branches.  But, adorned with a diadem and costly array, the emperor is denied entry to the city – indeed, the gate is suddenly miraculously bricked up. A vision of a flaming Cross and a messenger of God that appear above the gate command the emperor to enter the city in all humility, on a donkey, as did Christ.  Heraclius puts off his diadem, his purple garments, and his shoes, until his only covering is a linen garment.  Only then does the gate open, and the Cross performs its miracles of yore: lepers and lame are healed.  Moreover, the emperor gives many precious things.
A miniature in the Mont Saint-Michel Sacramentary (ca 1060) is the earliest depiction of the Restitutio (fig. 1).  The full-page miniature is framed by an acanthus border with a floral roundel midway along each side. In the upper register is Heraclius riding with eight companions. On the tower on the left stands an angel bearing a processional cross which he holds protected with a cloth. The same city appears in the scene below. Firstly Heraclius is depicted full-length, reverently holding the processional cross with a cloth. Then Heraclius is shown again, now barefoot and prostrate on the ground. For that matter, the prostration on the ground, the humilatio, is something that occurs frequently in monastic communities, and walking barefoot alludes to reverence for God, atonement or mourning, poverty and pilgrimage.  The eighth-century ordines Romani refer to the report of a Frankish monk from Einsiedeln concerning the Good Friday ceremony in Rome. The ordines mention that the procession bearing the relic of the Cross went barefoot from the Lateran to Santa Croce in Gerusalemme. 
In 1035, Duke Robert journeyed to Jerusalem, after he had donated many possessions to Mont Saint-Michel. According to the chronicle of Robert of Torrigny (1145-1158), the Archangel Michael had appeared to the duke in a dream and required him to make these benefactions (1027 or 1028).  The founding angel of the Normandy abbey played an important part in the Heraclius story, which might account for the increased interest in this iconographic motif. Also the sacramentary might have particular interest in the Heraclius story referencing that other important conquest of William the Conquerer in 1066. However, the miniature did not become a model.
From the 12th century onwards, the ages of the crusades, the Exultation iconography becomes widespread and becomes conventional in the liturgical and para-liturgical manuscripts. Exactly in that same period, the reception of that other motif of the legend takes place, the throne or decapitation of Chosroes. 
In 1878, M. J. Mohl published a German translation of the Firdausi verses written down in present-day Iran in 900 or thereabouts.  In this legend, a king builds a colossal "Taq dis"; etymologically this means "equal to the firmament" (fornici similis).  This "celestial throne" was made of the richest materials and embellished with all the signs of the zodiac. Four steps led up to a throne supported by lions. The Persian astrological throne functioned within a ritual context. As the center of the heavenly realm, the ruler was manifested as one who has power to influence the stars. Indeed, the ruler is venerated as the entity into which the cosmic powers have poured. The throne symbolizes this power.
In the Firdausi verses, it is told that Alexander the Great, indifferent to the treasures of the palace and unfamiliar with the astrological potential of the construction, destroyed the dazzling "Taq dis." However, Chosroes II conceived the plan of restoring the ancient astrological temple. T. Nöldeke suggests that the specific passage of the legend in which Chosroes II appears was based on the "Book of Chosroes," a lost Arabic chronicle that goes up to 628 AD.  Cedrenos (Historiarum compendium, 1057) also supplemented his Elevation of the Cross passage with a description of the astrological temple. 
The throne of Chosroes corresponds to the planetarium or the cosmic clock. Philostratus described such a structure in Babylon. The men’s hall in the palace had a domed vault that resembled the heavens. The dome was decorated with sapphires and with images of their gods, the planets.  At the time of early Christianity, planetaria were also made for private purposes. The Stephen martyrology tells of a pagan, Chromatius, who built a cubiculum holovitreum, in quo omnis disciplina stellarum ac mathesis mechanica as a device for healing. Even so, only with the help of Stephen did the sick recover. The pagan destroyed the construction and converted to Christianity. 
The descriptions in the Reversio homily are analogous. There is mention of many precious metals, of the sun and moon as a quadriga and of machinery kept in motion by horsepower. Persian textiles and precious metalwork still inform us about this sort of throne which was connected with the cult of the sun. Actually the cock was connected with the sun, and more specific with the rising sun. In the Arabic world, the cock is an image of victory and the Last Judgement.  The Sassanians practiced the alectryonomancia: divination by cocks and omen magic. The quadriga motif may also be an iconographic reminiscence of the heraldically-posed animals (usually bulls or lions) or horses harnessed to the chariot of the sun. 
In Christendom, the attitude to planetaria depended on the use to which they were put. As a place where the deification of the ruler took place –as they functioned in the East – they were repudiated. As works of art – as mimesisof the universe, thus – they were particularly appreciated by the Pythagorists. Notwithstanding their ambiguous associations, the phenomenon was familiar. In Hrabanus’ homily on the Elevation of the Cross, the cosmic throne acquired an extra function associated with the relic of the Cross, which Chosroes had set up next to his throne (iuxta eam).  Gotfried of Viterbo (ca. 1125-ca. 1192) added to this that Chosroes hoped the Cross would endow him with power to influence life and death.  This is a motif that embroiders on Chosroes’ legendary ability to manipulate the heavenly bodies and indicates the foolishness with which Chosroes uses the Cross as a magical object in a nature religion, failing to understand it as the mystery of the Passion. Moreover, in the legend, Chosroes is decapitated as the images of idols are decapitated. In the Middle Ages, the Saracens were the prototype of idolatry. 
In Chosroes’ cosmic throne, Christians recognized eschatological traditions from the Holy Scriptures and the Apocrypha. In Isaiah 14, 12-15, the fall of the king of Babylon is told: "How you are fallen from heaven, O Day Star, son of Dawn! How you are cut down to the ground, you who laid the nations low! You said in your heart, I will ascend to heaven; I will raise my throne above the stars of God; I will sit on the mount of assembly on the heights of Zaphon: I will ascend to the tops of the clouds, I will make myself like the Most High. But you are brought down to Sheol, to the depths of the Pit." The passage refers to the pride of Lucifer. According to 2 Thessalonians 2, 4: "He opposes and exalts himself above every so-called god or object of worship so that he takes his seat in the temple of God, declaring himself to be God." This pride is personified by the Antichrist. In the legend of the Exultation of the Cross, the figure of Chosroes is modeled on those of Lucifer and the Antichrist.
The eschatological conceptualization of Heraclius and Chosroes appears from the commentary on the Apocalypse written by Alexander of Bremen (Minorite, d. 1271), which is characterized by the search for links between the course of soteriological history and the End of Time. The passages were illustrated in three Latin manuscripts (fig. 2).  The Minorites were convinced that every event was a prefiguration of this End of Time. In this way, a textual structure was developed in which the Apocalypse is diachronically interwoven with soteriological history. The type of the historically interpreted Apocalypse was not new; it had already been developed in the Apocalypse of Pseudo-Methodius (ca. 655).  Pseudo-Methodius tells how the Last Emperor lays down his imperial insignia (crown and scepter) on Golgotha, surrendering them to God.  Alexander of Bremen adopts the same narrative structure in his commentary on Chapters 12 (the pregnant woman and the dragon) and 13 (the two beasts) of the Apocalypse, but he ascribes the roles of the "anonymous" characters of the Last Emperor and the Antichrist to Heraclius and Chosroes, respectively.
 The workshop was organized by The Chaim Herzog Center for Middle East Studies and Diplomacy. The Center is devoted to studies of the history, societies, and cultures of the Middle East. I thank Prof. Dr. Nimrod Hurvitz for his invitation to participate and Prof. Dr. Dror Ze’evi for his comments on my lecture.
 A Heritage of Holy Wood. The Legend of the True Cross in Text and Image, (Cultures, Beliefs and Traditions. Medieval and Early Modern Peoples, 22), Leyden, 2004.
 Most recent publications: W.E. KAEGI, Heraclius. Emperor of Byzantium, Cambridge, 2003; A. SOMMERLECHNER, Kaiser Herakleios und die Rückkehr des heiligen Kreuzes nach Jerusalem. Überlegungen zu Stoff-und Motivgeschichte, in Römische historische Mitteilungen, 45, Vienna, 2003, p. 319-360; G.J. REININK and B.H. STOLTE (eds.), The Reign of Heraclius (610-641). Crisis and Confrontation, Leuven, 2002.- Further: A. PERNICE, L'imperatore Eraclio. Saggio di storia bizantina, Florence, 1905; A. FROLOW, La vraie croix et les expéditions d'Héraclius en Perse, in Revue des études byzantines, 11, 1953, p. 88-105; O. VOLK, art. Herakleios, in Lexikon für Theologie und Kirche, 5, Freiburg, 1960, col. 237-238; G. OSTROGORSKY, Geschichte des byzantinischen Staates, Munich, 1963, p. 73-122; H.M. GUATKIN (ed.), The Cambridge Medieval History, 2. The Rise of the Saracens and the Foundation of the Western Empire, s.l., 1964, p. 184-302, p. 747-758; J.J. SAUNDERS, A History of Medieval Islam, London, 1965; V. GRUMEL, La reposition de la vraie croix à Jérusalem par Héraclius. Le jour et l'année, in Zeitschrift für Byzantinistik, 1, 1966, p. 139-149; A.N. STRATOS, Byzantium in the Seventh Century, 1. 602-634, trans. from the Greek by M. OGILVIE-GRANT, Amsterdam, 1968; W. DURANT, Weltreiche des Glaubens, (Kulturgeschichte der Menschheit, 5), reissue of 1935, Munich, 1981; J. HERRIN, The Formation of Christendom, Princeton, 1987, p. 183-219; M. GIL, A History of Palestine. 643-1099, trans. from the Hebrew by E. BROIDO, Cambridge, 1992, p. 65-74.
 A. PERTUSI (ed.), Giorgio di Pisidia poemi, I. Panegerici Epici, (Studia Patristica et Byzantina 7), 1960, p. 225-230, p. 235-239; I. BEKKERUS (ed.), Georgii Pisidae. Expeditio Persica, Bellum Avaricum, Heraclias, CSHB, 1836.
 C. De BOOR, Theophanis Chronographia, 2, reissue of Leipzig, 1885, Hildesheim 1963, p. 179-213; C. MANGO (ed.), The Chronicle of Theophanes Confessor. Byzantine and Near Eastern History ad 284-813, Oxford, 1997, p. 441-455.
 G.J. REININK, Die Entstehung der syrischen Alexanderlegende als politisch-religiöse Propagandaschrift für Herakleios Kirchenpolitik, in After Chaldecon. Studies in Theology and Church History. Offered to Professor Albert van Roey For His Seventieth Birthday, (Orientalia Lovaniensia Analecta, 18), Leuven, 1985, p. 263-281, 267.- Editie: E.A.W. BUDGE, The History of Alexander the Great. Being the Syriac Version. Edited from Five Manuscripts, of the Pseudo-Callisthenes, Amsterdam, 1976 (reissue of Cambridge 1889), p. 255-275, p. 144-148.- In the Syrian legend, Alexander promises that he will leave his silver throne to Jerusalem. The imperial throne is regarded as foreshadowing Christ’s throne; A. CAMERON, Images of Authority. Elites and Icons in Late Sixth-Century Byzantium, in Past and Present, 84, 1979, p. 3-35, p. 17. On the basis of the Alexander-Heraclius typology, a tradition developed around the so-called "throne of Heraclius," which was behind the main altar of San Marco in Venice but was moved to the baptistery of the church in 1524; W. DORIGO, La cosidetta "cattedra di San Marco" in Venezia Arti, 3, 1989, p. 5-13. According to tradition, Heraclius would have received the throne in Alexandria and subsequently offered it to Grado. Another tradition has it that Helena brought the throne from Alexandria, and it was offered to Elias of Grado later (572-568).
 B.M. WHEELER, Imagining the Sasanian Capture of Jerusalem, in Orientalia christiana periodica, 57, 1, 1991, p. 69-85.
 I. LEVI, L'apocalypse de Zorobabel et le roi de Perse Siroès, in Revue des Etudes Juives, 68, 1914, p. 129-160; G. GARITTE, La prise de Jérusalem par les Perses en 614, CSCO, 202-203, (Scriptores Iberici, 11-12), Leuven, 1960. For the Arab perception of Heraclius, see: M. COOK, The Heraclian Dynasty in Muslim Eschatology, in al-Qantara, 113, 1992, pp. 3-23. With thanks to Dr. Daniella Talmon-Heller, Ben Gurion University, Israel.
 M. WHITBY, George of Pisida’s Presentation of the Emperor Heraclius and his Campaigns, in The Reign of Heraclius, op. cit., p. 157-173; J.W. DRIJVERS, Heraclius and the restitutio crucis. Notes on Symbolism and Ideology, in Ibidem, p. 175-190.
 W. KAEGI, op. cit., 2003, p. 205.
 W. DURANT, op. cit., p. 405-425; J.J. SAUNDERS, op. cit., p. 18-38.
 G. OSTROGORSKY, op. cit., p. 92-93. On the last phase of Heraclius’s rule, see: H. MANANDEAN, Les invasions arabes en Arménie (Notes chronologiques), in Byzantion, 18, 1948, p. 163-195, p. 163; W.E. KAEGI jr., Heraklios and the Arabs, in The Greek Orthodox Theological Review, 27, 1, 1982, p. 109-133. An investigation of the Arabic sources and especially of the view on Heraclius expressed in them is beyond the scope of the present volume. Tabari’s tenth-century chronicle provides a suitable line of approach here; T. NÖLDEKE, Geschichte der Perser und Araber zur Zeit der Sassaniden aus der arabischen Chronik der Tabari übersetzt, Leiden, 1879, p. 365 ff. I may note here that "the history of the conquest of Syria" (the Ta'rikh Futuh al-Sham, seventh or twelfth [?] century), includes a speech by Heraclius, in which he warns the Syrians against the Arabs and claims their loyalty as a buffer state by referring to the recent victories over Chosroes II. In that connection Heraclius calls the Persians the "magicians" and the Avars, "those who know no God" (W.E. KAEGI jr., art. cit., p. 113). The Persians are not only associated with magic because of their nature religion and demonologies but also because of their cultural and political dependence on astrology; B.L. van de WAERDEN, art. Astronomie, in Lexikon des Mittelalters, 1, Munich, 1980, cols. 1146-1153, col. 147; J.R. RUSSELL, art. cit., p. 661.
 J.W. DRIJVERS, art. cit., p. 190.
 See: L. van TONGEREN, Exaltation of the Cross. Toward the Origins of the Feast of the Cross and the Meaning of the Cross in early Medieval Liturgy, Leuven, 2000.
 HRABANUS MAURUS, Homilia LXX, PL 110, col. 131-134. This is the same text as the Exaltatio seu reversio sanctae crucis in the Bibliotheca hagiographica latina. Antiquae et mediae aetatis, ed. Socii Bollandiani, Brussels, 1911, no. 4178. PL 110, col. 1142: "Et in Hierosolyma passio sancto Judae, sive Quiraci episcopi, cui revelatum est lignum Dominicae crucis" is a very short reference to the Finding of the Cross.
 Kindly mentioned to me in a correspondence on 12 July 2004.
 "Pergens igitur filius Chosroe contra Gracchum, iuxta Danubium magnum fluvium consedit exercitus. Tandem inspirante clementia Salvatoris, utrisque principibus placuit ut ipsi singuli in medio ponte fluminis dimicaturi confligerent, et cui sors victoriam contulisset" (PL 110, col. 132, D).- The localization on the Danube is a historical anomaly. In the seventh century, the Danube constituted the natural border with the Avar Empire and at the time of Hrabanus Maurus with the Hungarians and the Magyars. Although, of course, the Avars were also hostile to the Byzantine Empire, they had no direct connection with the conflict with the Persians. However, it is known, that Emperor Maurice conducted several "Danube campaigns" against the Avars (G. OSTROGORSKY, op. cit., p. 77). After his victory over the Persians, Heraclius expelled the Avars from Constantinople. It is also possible that Hrabanus projected the contemporary threat of the Hungarians onto the battle of Heraclius. See also: H. WOLFRAM and F. DAIM, Die Volken an der mittleren und unteren Donau im fünften und sechsten Jahrhundert, (Österreichische Akademie der Wissenschaften. Philosophisch-historische Klasse. Denkschriften, 145), Vienna, 1980. As a natural border, the Danube plays an important and "universal" part in the European battles against heathenism. The Tigris and the Euphrates are perceived in a similar way in the East. Ctesiphon, the capital of the Sassanian Empire, was also connected to the "outer world" by a bridge over the Tigris. Is the Tigris the Danube of the Persians? In his version of the Exaltation of the Cross (1170), Johannes Belethus incorporates a correction: "... Danubium illum, qui apud Persas est, non hunc qui in Suevia oritur" (Rationale divinorum officiorum, PL 202, col. 152).
 "Cumque imperator de monte Oliveti descendisset per eam portam quam Dominus intraverat quando ad passionem venerat..." (PL 110, col. 133, C).
 "Repente lapides portae descendentes, clauserunt se invicem, et factus est paries unus... viderunt signum sanctae crucis in coelo, flammeo fulgore resplendere. Angelus enim Domini aspiciens illud in manibus, stetit super portam et ait: Quando rex coelarum Dominus totius mundi passionis sacramenta per hoc aditum completurus introiit, non se purpuratum, nec diademate nitentem exhibuit, aut equi potentis vehiculum requisivit, sed humilis aselli terga insidens" (PL 110, col. 133 D).
 "Tunc imperator gaudens in Domino de visu angelico, depositisque imperii insignibus, discalceatus, protinus, lintea tantum zona praecinctus, crucem manu suscipiens" (PL 110, col. 134 A).
 "Vexillum," "crux," "partem ligni," "admirabile signum," "dulce lignum," and "splendidior astris" are used interchangeably in this context (PL 110, col. 134 B-C).
 New York, Pierpont Morgan Library, ms. 641, fol. 155v; F. AVRIL, La décoration des manuscrits du Mont Saint-Michel. 11e-12e siècle, in Millénaire monastique du Mont Saint-Michel, 2. Vie montoise et rayonnement intellectuel, 1967, p. 203-238, p. 218-223; M. BOURGEOIS-LECHARTIER, A la recherche du scriptorium de l’abbaye du Mont Saint-Michel, in Ibidem, p. 171-202 J.J.G. ALEXANDER, Norman Illumination at Mont St. Michel. 966-1100, Oxford, 1970, p. 157-159, fig. 44; G. NORTIER, Les bibliothèques médiévales des abbayes bénédictines de Normandie, Paris, 1971, p. 63-82; M. DOSDAT, L’enluminure romane au Mont Saint-Michel, Xe-XIe siècles, Avranches, 1991, p. 58-61; M. BAYLE, P. BOUET, J.P. BRIGHELLI e.a., Le Mont-Saint-Michel. Histoire et imaginaire, Paris, 1998, passim; M. DOSDAT, Le scriptorium du Mont-Saint-Michel el les images de la foi. Manuscrits enluminés du Xe au XIe siècle, in Images de la foi. La Bible et les Pères de l’Eglise dans les manuscrits de Clairvaux et du Mont-Saint-Michel, Paris, 2002, p. 21-29; A. SOMMERLECHNER, art. cit., 2003, note 174, fig. 1.
 W.M. GRAUWERS, De betekenis van het blootsvoets lopen in de middeleeuwen, voornamelijk in de 12de eeuw, in Archief- en bibliotheekwezen in België, 42, 1971, p. 141-155.
 M. ANDRIEU (ed.), Les Ordines Romani du Haut Moyen Age, (Spicilegium Sacrum Lovaniense, 11, 23- 24-28-29), 5 vols, Leuven, 1957-1961, vol. 3, p. 270-271.- See also the study concerning pilgrims’ customs in Rome: M. D'ONOFRIO, Romei e Giubilei. Il Pellegrinaggio medievale a San Pietro (350-1350), Milan, 1999.
 In a twelfth-century manuscript of the chronicle preserved in Avranches (Bibliothèque de la Ville, ms. 210, fol. 25v), the events are illustrated (fol. 25v). The two registers of the drawing should be read from bottom to top. Below left, the angel appears to Robert, who in the next scene places a large glove on the altar of St Michael. The glove is a symbolical gesture deriving from legal jargon and showing that he gives up his property. At the top, the angel hands the brand new foundation to the abbot in the form of a flowering twig. The Angel Michael is represented here twice in his capacity as a dragon slayer; B. BÄNSCH, Der Schatz der Goldener Tafel zu Lüneburg bis 1245, in Heinrich der Löwe und seine Zeit. Herrschaft und Repräsentation der Welfen 1125-1235, 2. Essays, (exhibit cat.), Munich, 1995, p. 313-328, p. 314, fig. 193.
 E. HERZFELD, Der Thron der Khosrô. Quellenkritische und Ikonographische Studien über Grensgebiete der Kunstgeschichte des Morgen- und Abendlandes, in Jahrbuch der Preuszischen Kunstsammlungen, 41, 1920, p. 1-24 and p. 103-147; H.P. L'ORANGE, Studies on the Cosmic Kingship in the Ancient World, Oslo-Cambridge, 1953; L.-I. RINGBOM, Gralstempel und Paradies. Beziehungen zwischen Iran und Europa im Mittelalter, Stockholm, 1951; IDEM, Paradisus terrestris. Myt, Bild och verklighet, Helsinki, 1958 (with English summary p. 422 ff).
 M.J. MOHL (ed.), Le livre des Rois par Abou'lkasim Firdausi, 7 vols, reprint of 1878, Paris, 1976, VII, p. 306-315.
 E. HERZFELD, art. cit., p. 1.
 T. NÖLDEKE (ed.), Geschichte der Perser und Araber zur Zeit der Sasaniden aus der arabischen Chronik des Tabari übersetzt, Leiden, 1879, introduction
 I. BEKKERUS (ed.), Georgius Cedrenus. Historiarum Compendium, 1, Bonn, 1838, p. 721 ff- E. Herzfeld deduces from this that Cedrenos, as was his habit, only gave an abridged version and that he must have read it either in a lost Theophanes edition or in a source prior to this one; E. HERZFELD, art. cit., p. 19.
 Translated from Philostratus, Apollonios, I, 25, 15; A. ALFÖDI, Insignien und Tracht der römischen Kaizer, in Mitteilungen des Deutschen Archäologischen Instituts. Römische Abteilung, 50, 1935, p. 128; F. CONYBAERE (ed.), The Life of Apollonius of Tyana. The Epistles of Apollonius and the Treatise of Eusebius, (The Loeb Classical Library, 16-17), London, 1969, 1, p. 77; V. MUMPRECHT (ed.), Das Leben des Apollonius von Tyana, Munich, 1983, p. 83: (A man’s hall) "dessen Dach sich zu einer dem Himmel vergleichbaren Kuppel wölbte und bedeckt war mit Saphirsteinen und in dem Bilder von Göttern an die sich glaubten (...). Hier hält der König Gericht."
 Vita fabulosa S. Stephani protomartyris, BHL, 1911, no. 7849; G. HENSCHENIUS and D. PAPEBROCHIUS, Acta Sanctorum. Januarii tomus secundus, Paris-Rome, 1866, p. 273.
 M. CHEEBEL, art. Coq, in Dictionnaire des symboles. Rites, mystique et civilisation, Paris, 1995, p. 112-113.
 See also: P.O. HARPER, art. Sasanian art, in Dictionary of the Middle Ages, 10, New York, 1988, p. 656-660.
 Byzantine and Arabian chronicles do mention the stealing of the Cross (vexillum) from Jerusalem (Pisides) and the restitution of it (Theophanes), but not its integration into the astrological clock itself.
 GOTFRIED OF VITERBO, Pantheon, PL 198, col. 912-915.
 M. CAMILLE, The Gothic Idol. Ideology and Image-making in Medieval Art, Cambridge, 1989, p. 129-164.
 1. Cambridge, University Library, Ms. Mm. 5.31, fol. 79r, 80v, 81v; G. SCHILLER, op. cit., 5, p. 472-473; M. M(ICHAEL), art. Friar Alexander, Commentary on the Apocalypse, in The Apocalypse and the Shape of Things to Come, ed. by F. CAREY, (exhb. cat.), London, 1999, p. 83-84; 2. Breslau, Staats- und Universitätsbibliothek, I, Qu 19, fol. 64v: Decapitation of Chosroes; M. HUGGLER, Der Bilderkreis in den Handschriften der Alexander-Apokalypse, in Antonianum, 9, 1934, p. 85-150, fig. 9; 3. Prague, Bibliothek des Metropolitanskapitels, Cim. 5, fol. 80v: Decapitation of Chosroes; See also: R. CHADRABA, art. Antichrist, in Lexikon der christlichen Ikonographie, 1, Rome-Vienna, 1968, col. 119-122.
 Text edition: E. SACKUR, Sibyllinische Texte und Forschungen. Pseudomethodius, Adso und die Tiburtinische Sibylle, Halle, 1898, p. 644-674; A. LOLOS, Die Apokalypse des Ps.-Methodius, Meisenheim-am-Glan, 1979 (Greek).
 As is known, the legend of the Last Emperor has had a strong influence on political-theological thought in the Middle Ages (especially in the Holy Roman Empire). In the Cologne Book of Sibyls, Frederick I Barbarossa is given all the characteristics of the Last Emperor; See: W. GREBE, Sibyllen Weissagung, Cologne, 1989.
 Ibidem, p. 101, note 2: Chronica Slavorum, ed. J.M. LAPPENBERG, vol. I, cap. I-XII, MGH SS 21, 1869, p. 101 ff.
 Ibidem, p. 92. In the Sächsische Weltchronik, 1260, Gotha, Forschungsbibliothek, Codex Memb. I. 90, fol. 65v, the battle is also a duel.
 Ibidem, p. 121, noot 26: MGH (1859), 231: "quia in hoc resedit examinatum quampluries nostrorum consilium, quod esset salubrius nobis et toti Europe, ut Danubius fortaliciis muniretur. Hec enim est aqua contradictionis, hic Eraclius occurrit Cosdroes pro Romano imperio defendo, et hic eciam nos quantumcumque improvisi, et tunc enormiter lesi per decem menses contradiximus Thartaris, regno nostro tunc fere penitus fortaliciis et defensoribus immunito, quod, quod absit, si possideretur a Thartaris, esset pro ipsis apertum hostium ad alias fidei catholice regions."
 See also: M. CURSCHMANN, Constantine-Heraclius. German Texts and Picture Cycles, in Piero della Francesca and His Legacy, ed. M.A. LAVIN, (Studies in the History of Art, 48), Hannover-London, 1995, p. 49-61, in the cycle of 1350 in Fraurombach, Oberhessen. Here the childhood of Heraclius according to a Byzantine courtlegend is depicted too. Fraurombach depended on Fulda.
 Ibidem, p. 122-123.
 See: B. DUNN-LARDEAU (ed.), Legenda Aurea. Sept siècles de diffusion. Actes du colloque international sur la Legenda Aurea. Texte latin et branches vernaculaires à l'Université du Québec à Montréal 11-12 mai 1983, Montreal-Paris 1986: several case-studies.
 On the discovery of the True Cross, the Inventio crucis, see: S. BORGEHAMMAR, How the Holy Cross Was Found. From Event to Medieval Legend. With an Appendix of Texts, Stockholm, 1991; J.W. DRIJVERS, Helena Augusta. The Mother of Constantine the Great and the Legend of Her Finding of the True Cross, Leiden-Cologne, 1992. The Inventio crucis and the Restitutio crucis became united in the so-called legend of the True Cross.
 I cannot go further into this: see B. BAERT, The Figure of Seth in the Vault-Paintings in the Parish Church of Östofte. In Search for the Iconographical Tradition, in Konsthistorisk tidskrift, Stockholm, 66, 2, 1997, p. 97-111, IDEM, La Piscine Probatique à Jérusalem. L'eau médicinale au Moyen Age, in Als Ich Can. Liber Amicorum in Memory of Professor Dr. Maurits Smeyers, ed. B. CARDON e.a., Leuven, 2002, p. 91-129
 S. PFLEGER, Eine Legende und ihre Erzählformen. Studien zur Rezeption der Kreuzlegenden in der italienischen Monumentalmalerei des Tre- und Quattrocento, (Europäische Hochschulschriften, 18. Kunstgeschichte, 214), Frankfurt-Vienna 1994, p. 53-72 on the cycle and p. 123-129 on the patrons. A testament by Alberto di Lapo degli Alberti from 1348 (during the plague) demonstrates for certain the earliest contact between the family and the Franciscan convent (Florence, Archivio di Stato, Diplomatico S. Croce 1348; S. PFLEGER, Eine Legende, p. 125-126).
 The documents of the Compagnia della santa Croce in Montepulciano relate that in 1415 a voyage to Florence was financed for Nanni (Giovanni) di Caccia to study Gaddi’s frescoes in the Santa Croce; A. LADIS, Un' ordinazione per disegni dal ciclo della vera croce di Agnoli Gaddi a Firenze, in Rivista d'arte, 41, 1989, p. 153-158.
 Bonaventura, Opera omnia, Legenda major, XIII, 3: "seraph unum effigies hominis crucifixi christo sub specie seraph ... circa festum exaltationis sanctae crucis"; D.V. MONTI, Francis of Assisi, in The Encyclopedia of Religion, ed. M. ELIADE, 3, New York-London 1987, p. 407-408. Also mentioned in the 13th-century Fioretti of Ugolino; G.D. BONINO (ed.), I fioretti di San Francesco, Turin 1974, p. 176, p. 180.
 L. LEHMANN, Prinzipien Franziskanischer Mission nach den frühen Quellen, in Francescanesimo e profezia, ed. E. COVI, Rome 1985, p. 144, especially regarding the threat of Islam, but also with respect to the Byzantine Orthodox Church; G. SPIERIS, Francesco d'Assisi. Profeta dell' incontro tra Occidente e Oriente, in Francescanesimo e profezia, p. 453-489.
 G. ODOARDI, La custodia di Terra Santa nel VI. centenario della sua costituzione, in Miscellanea francescana, 43, 1943, p. 217-256.
 L. LEHMANN, Prinzipien, passim.
 Thanks to Prof. Dr. Don Giuseppe Avarucci, Università di Macerata, who alerted me to this fact.
 L. SCHNEIDER, The Iconography of Piero della Francesca's Frescoes Illustrating the Legend of the True Cross in the Church of San Francesco in Arezzo, in The Art Quaterly, 32, 1969, p. 23-48; M.A. LAVIN, Piero della Francesca and His Legacy, (Studies in the History of Art 48), Hannover-London, 1995; IDEM, Piero della Francesca: San Francesco, Arezzo-Paris, 1995; C. GINZBURG, Enquête sur Piero della Francesca. Le Baptême, le cycle d'Arezzo, la Flagellation d'Urbino, Paris, 1981, p. 33-63 ; J. BECK, Piero della Francesca at San Francesco in Arezzo. An Art-Historical Peregrination, in Artibus et historiae. An Art Anthology, 47, 2003, p. 51-80.
 M.A. LAVIN, art. cit., p. 148.
 C. GINZBURG, op. cit., p. 56; see: L. MOHLER, Kardinal Bessarion als Theologe, Humanist und Staatsmann, Aken, 1967; J. GILL, Was Bessarion a Conciliarist or an Unionist Before the Council of Florence, in Collectanea byzantina, Rome, 1977, p. 201-219; H. VAST, Le cardinal Bessarion (1403-1472). Etude sur la Chrétienté et la Renaissance vers le milieu du XVième siècle, Genève, 1977; G. FIACADORI, Bessarion e l'umanismo, (exhib. Cat.), Venice, 1994.
 C. GINZBURG, op. cit., p. 57; G. MERCATI, Per la cronologia della vita e degli scritti do Niccolò Perotti arcivescovo di Siponto, Rome, 1925.
 A. FROLOW, La relique de la vraie croix. Recherches sur le développement d'un culte, Parijs, 1961, p. 563-565.
 See: B. BAERT, La cappella Farfense in Montegiorgio. Una leggende della vera croce nelle Marche (ca 1425), in Arte cristiana, 804, 2001, p. 219-233; B. BAERT, The Wall Paintings in the Campanile of the Church of St. Nicola in Lanciano (ca. 1330-1400). Reading an Unknown Legend of the Cross in the Abruzzi, Italy, in Iconographica, 2, 1, 2003, p. 108-125.
 H. KOLLER, Der Thron Khosraus II. Zu den Chorgemälden in der Kirche von Wiesendangen, s.l., s.d., p. 93-99; E. RAMP, Die legende vom heiligen Kreuz. Ihre Bedeutung und ihr geschichtlicher Hintergrund, in Winterthurer Jahrbuch, 1969, p. 63-76; Chr. and D. EGGENBERGER, Malerei des Mittelalters (Ars Helvetica, 5. Die visuelle Kultur des Schweiz), Bern, 1989, p. 162-167; J. MICHLER, Gotische Wandmalerei am Bodensee, Friedrichshafen, 1992, p. 134-150.
 A. FROLOW, Les reliquaires de la vraie croix, Paris, 1965, p. 508, nr. 715.
 F. CAPPELLETTI, L'affresco nel catino absidiale di Santa Croce in Gerusalemme a Roma. La fonte iconografica, la committenza e la datazione, in Storia dell'arte, 66, 1989, p. 119-126; G. SCAVIZZI, The Cross. A 16th Century Controversy, in Storia dell'arte, 65, 1989, p. 27-43; M. BASILE BONSANTE, Dal racconto all’icona. Modelli iconografici della "Historia Crucis" tra Cinque e Seicento, in M. Stella Calò MARIANI (ed.), Il cammino di Gerusalemme. Atti del II Convegno Internazionale di Studio (Bari-Brindisi-Trani, 18-22 maggio 1999), Bari, 2002, p. 387-416. On Heraclius in late medieval popular culture, see L. KRETZENBACHER, Kreuzholzlegenden zwischen Byzanz und dem Abendlande, (Bayerische Akademie der Wissenschaften. Philologisch-historische Klasse. Sitzungsberichte, 3), Munich, 1995.