The House of Wisdom

by Jonathan Lyons

  His running war of words with the popes, at times drifting into armed conflict, led to a church-inspired whisper campaign claiming that Frederick was actually the Antichrist, a rumor bolstered by the circumstances surrounding his birth. Frederick’s mother was the posthumous daughter of Roger II, and it was said that she had been hidden away in a convent at an early age amid predictions that she would one day bring disaster to the land. At age thirty, she married Frederick’s father, ten years her junior, and the pair were childless for almost a decade before her unexpected pregnancy. A popular superstition of the day said the Antichrist would be born by a nun, and soon many fingers were pointed at Frederick.1

  This rumor campaign also fed on the emperor’s well-known affinity for the world of Islam, which discomfited both the church and his own Christian subjects. One scandalized European contemporary wrote, “When the time came for the midday prayer and the muezzin’s cry rang out, all his pages and valets rose, as well as his tutor, a Sicilian with whom he was reading Aristotle’s Logic in all its chapters, and they offered the canonic prayer, for all were Muslims.”2 This was a view more appreciated by a prominent Arab ambassador to Frederick’s court: “He was distinguished among all the kings of the Franks for his talents and his taste for philosophy, logic, and medicine; he had an appreciation of the Muslims since he had been reared in Sicily where the majority of the inhabitants profess Islam.”3 Yet other Arab commentators were put off by his poor physical stature, ruddy face, balding head, and failing eyesight: “If he had been a slave, one would not have paid 200 drachmas for him,” quipped one.4

  Still, Frederick II was the subject of widespread popular awe; some called him stupor mundi, the wonder of the world. On a famous visit to the Italian city of Ravenna in 1231, Frederick marched through the streets with his personal menagerie of strange and wild beasts, many then unknown to the locals. These included elephants, camels, panthers, white falcons, and Europe’s first giraffe—a present from al-Kamil, the sultan of Egypt.5

  In the winter of 1229, the maverick emperor succeeded where previous crusaders had repeatedly failed: He reclaimed control of Jerusalem, captured from the Christians more than four decades before by the celebrated Muslim warrior Saladin. Frederick had arrived in the Latin East eight months earlier, albeit after much stalling and numerous delays, but he did not follow the course of the earlier Crusaders to attain his goal. In fact, no blood was shed at all. Instead, Frederick painstakingly negotiated the peaceful handover of Jerusalem and surrounding territory with Sultan al-Kamil, who then controlled the Holy Land.

  Reports say the talks between the two sides, held in secret and subject to wild rumormongering by jealous church officials fearful that Frederick had lost all taste for religious warfare, dragged on and on. The patriarch of Jerusalem, a bitter enemy of the emperor, at one point lamented to his allies at the papal court in Rome, “It is with the greatest shame and disgrace that we report to you that it is said the sultan, hearing of the emperor’s enjoyment of living in the manner of the Saracens, sent him singing girls and jugglers, persons who were not only of ill report but unworthy even to be mentioned among Christians.”6 A German poet, on crusade with the emperor, compared al-Kamil and Frederick to a pair of stubborn misers unable to agree on how to divide three pieces of gold.7 At last, the two sides reached a settlement, and Frederick, the reluctant crusader, could claim success. The deal included formal Christian control of the city, including the historic burial place of Christ, but also guaranteed Muslim access to the Islamic holy sites. It stipulated a ten-year cessation of hostilities, much to the chagrin of the bellicose members of the papal party, who wanted no part of any diplomacy with the infidels.

  Seen outside the narrow perspective of the papal curia, Frederick’s achievement was a remarkable triumph—not for Christian arms but for a new standard of political, diplomatic, and intellectual commerce with the Arab world. The Holy Roman emperor never had enough troops at his disposal to take Jerusalem by force. Besides, the Arabs had patched up their latest internal disputes and were now more than a match for the Army of the Cross. Still, Frederick was desperate for some kind of victory. His struggle with the popes and other political pressures back home demanded that he return to Italy triumphant. Playing the only real card he had, the emperor reminded al-Kamil relentlessly that he had come to the region at the latter’s request to help against a rival Muslim ruler in Damascus. That quarrel may have been resolved by the unexpected death of the sultan’s adversary, Frederick noted, but he had set off in good faith. He could not go home empty-handed. “If he had not feared injury to his honor, he would not have demanded so great a sacrifice of the sultan,” writes the medieval Egyptian historian al-Maqrizi.8

  At first the sultan was unimpressed by such blandishments. He no longer needed the emperor’s assistance, and the handover of Muslim-held territory would certainly unnerve his subjects and anger the clergy. But Frederick slowly wore down the sultan with months of patient diplomacy, backed by a clever cultural offensive. The emperor closeted himself with al-Kamil’s special envoy, engaging him in fluent Arabic in rambling discussions of science, philosophy, and religion. He sent mathematical puzzles and philosophical riddles to the sultan’s court in Cairo, where they were discussed by leading Arab scholars. Apparently moved by Frederick’s persistence and his knowledge of, and respect for, Arab learning and the Muslim faith, the sultan at last relented. Frederick’s well-known battles with the popes in Rome may also have played a part; by assisting Frederick, the Arabs would indirectly deal a blow to these “Christian caliphs,” the leading proponents of the anti-Muslim Crusades.

  Much had changed since the time of Peter the Hermit and the First Crusade, more than 125 years earlier. The Muslim was no longer simply the faceless enemy of Christendom. Islamic learning had already begun to make deep inroads into the European consciousness. Peter the Venerable, the powerful abbot who had ordered the translation of the Koran the better to attack the “heresy” of Islam, had conceded publicly that the Arabs were particularly clever at science and philosophy. General enthusiasm for the Crusades was also on the wane among the European public. England and France, once reliable founts of crusading zeal, were busy fighting each other. A recent expedition against the Muslims, led at the pope’s insistence by a prelate and not an experienced military or political figure, had ended in disaster. Critical verses, sung by the troubadours, ridiculed that campaign and further undercut popular support for the entire venture.9 Frederick himself only went along in the face of unrelenting pressure from the popes, with whom he was eager to prevent a final, irreparable rupture in relations.

  By now, a growing network of commercial, political, and intellectual ties had slowly begun to bind East and West. Known among the Arabs as al-Emberor, Frederick II was a product of this emerging Europe—engaged with the broader world, its ideas, and its culture. Patterning his court after that of his grandfather and the Arab rulers of his own day, al-Emberor offered generous financial rewards to draw top intellectual talent into his retinue. He supported Muslim and European scholars and corresponded with learned figures and rulers throughout North Africa, al-Andalus, and other centers of Arab science. Nor was his patronage limited to Christians and Muslims. Jacob Anatoli, the prominent Jewish translator of Arab science and philosophy, newly arrived from Provence, praised the emperor as a “friend of wisdom and its votaries” for his financial support.10 Judah ben Solomon ha-Cohen, an Andalusi Jew and the author of an encyclopedia of philosophy, corresponded with the court and even visited Frederick in northern Italy.11

  Frederick’s overbearing personality and autocratic style left him suspicious of any institution he could not control completely. Universities in his realm developed only slowly and never really competed with the great early centers in Paris and Oxford. Frederick saw the university at Naples and the famed medical school at Salerno as little more than reliable sources of trained administrators and courtiers, rather than as independent institutions of learning.12 As an inc
ubator of the arts and sciences, however, the court of Frederick II played an important role in the transmission to the West of the studia Arabum. The great Catholic thinker Thomas Aquinas began his university career at Naples—founded by Frederick in 1224—before moving on to Paris, then the center of European theological and philosophical thought. And it was certainly at Naples that Thomas was first exposed to the Arab philosophical tradition.

  On March 18, 1229, the Holy Roman emperor made his symbolic entrance into Jerusalem, where he spent a single night. His only regret, he later said, was that local Muslim officials had suspended the calls to prayer out of respect for the Christian monarch; he had longed to hear the summons of the muezzin ring out across the old city before dawn. Such respect for al-Emberor was not shared by the local Franks. The citizenry of Acre pelted him with garbage as he boarded his ship for the homeward voyage. Even after his return to Italy, Frederick remained in touch with Sultan al-Kamil. The pair continued to exchange correspondence and diplomatic gifts, and the sultan even sent his friend one of his most learned philosophers to instruct the Christians further.13

  Michael Scot joined this Arabized court sometime in the mid-1220s on the strength of a reputation earned in Spain. He had arrived in Toledo around 1217 and set about translating an important Arab treatise on the heavens and three of Aristotle’s most influential works, On Animals, On the Heavens, and On the Soul, from the Arabic versions. As Frederick’s science adviser and court astrologer, Michael later published a translation of Avicenna’s work on zoology and wrote widely on astrology, meteorology, and physiognomy—all of the works dedicated to al-Emberor. These works show Michael’s acquaintance with medicine, music, and alchemy, as well as Aristotelian philosophy in general. Pope Honorius III called Michael “singularly gifted in science among men of learning,” while another pope testified to his facility with Arabic and Hebrew.14 The papal court was instrumental in securing support for this roaming scholar and occasional minstrel in the form of stipends from the revenue of church properties. We are told he also had respectable knowledge of Arab astronomy and its applications and prided himself on his meticulous calculations.15

  His ties to Frederick now put Michael at the intellectual and cultural heart of the new Europe, and after the difficulties he had faced as an impoverished student and young master, he was determined to make the most of it. “One who wishes to have honor among the peoples of the world will gain it either by divine providence such as becoming bishop, abbot, or patriarch by perfect election, or by perfect work, which is had by genius of nature or art, such as being an approved master of some faculty,” he writes in one illuminating passage.16 Clearly, Michael had traded in his transitory skill with the lute for the hope of lasting fame through the written word.

  Michael used the platform afforded by the imperial court to promote radical ideas, new learning, and novel technologies. Among his protégés was Leonardo of Pisa, also known as Fibonacci and today considered one of the greatest mathematicians of all time. Like Michael and his lord Frederick, Leonardo was the product of an increasingly worldly Europe. His father was a Pisan merchant in the city-state’s North African enclave, in modern-day Algeria, and he sent his young son to learn the latest arithmetic and accounting methods, including the basis for the Italian art of double entry bookkeeping, from the local Muslim traders.17 Leonardo later traveled to Sicily, Egypt, southern France, and Constantinople, before returning to his native Italy. There, in 1202, he completed The Book of Calculation—the first comprehensive work in Christian Europe on algebra and geometry.18 It also provided the most detailed Latin account to date of working with the Arabic number system, first spelled out by al-Khwarizmi: “Here Begins the First Chapter,” writes Leonardo. “The nine Indian figures are: 987654321. With these nine figures, and with the sign 0 which the Arabs call zephyr (al~sifr), any number whatsoever is written.”19

  Leonardo’s work came to the attention of Michael, who sent the mathematician a detailed commentary, including proposed changes and corrections to The Book of Calculation. Michael also ensured that the Italian scholar would have the backing of the emperor, who delighted in Leonardo’s ability to solve mathematical puzzles that had stumped some of the leading Arab experts with whom Frederick was in regular correspondence. A later edition of The Book of Calculation thanks Michael on both scores: “You, my Master Michael Scott, most great philosopher, wrote to my Lord [Frederick II] about the book on numbers which some time ago I composed and transcribed to you; whence complying with your criticism, your more subtle examining circumspection, to the honor of you and many others, I with advantage corrected this work … Further, if in this work is found insufficiency or defect, I submit it to you for correction.”20

  Leonardo produced major treatises on geometry, second-degree equations, and the practical needs of a growing international mercantile class—converting multiple currencies, allocating shares in commercial partnerships, working with varying units of measure—and he anticipated the coming use of decimal fractions. In an unusual departure from the conventions of his day, Leonardo omitted references to mystical numerology, and he was more than willing to acknowledge Arab contributions to his art.21 “In solving problems there is a certain method called ‘direct’ that is used by the Arabs, and that method is a laudable and valuable method, for by it many problems are solved.”22 A number of his books addressed in detail some of the very puzzles that Frederick had posed to him and other contestants in court-sponsored mathematics tournaments, but none enjoyed anything like the popularity accorded the more derivative Book of Calculation.

  Leonardo also developed what has come to be known as the Fibonacci sequence, based on his solution to a puzzle on the breeding fortunes of rabbits. The Book of Calculation poses this riddle as follows: “A certain man had one pair of rabbits together in a certain enclosed place, and one wishes to know how many are created from the pair in one year when it is the nature of them in a single month to bear another pair, and in the second month those born to bear also.”23 The resulting pattern of numbers Leonardo generated in his solution has been found to address an entire range of scientific and mathematical problems. Today, application of this famous sequence is the subject of its own scholarly journal, the Fibonacci Quarterly, and it has been used for decades by technical market analysts trading stocks, bonds, and other instruments.

  Frederick’s reign—he was crowned in 1198 as a boy of four and died in 1250—marked an important way station in the West’s long journey toward the great scientific advances of the seventeenth century. Perhaps unique among contemporary European rulers, this second of the “baptized sultans” sought to ground his worldview in reason, a hallmark of the coming scientific method. This approach was at the heart of the emperor’s decision to abolish trial by ordeal—the same system of justice once ridiculed by Usama ibn Munqidh, the Syrian commentator on the early crusaders. It was, Frederick concluded, a method that did not lead to truth and could not be justified by reason.24

  In an original treatise on falconry, Frederick goes well beyond a somewhat cursory study one hundred years earlier by Adelard of Bath by incorporating material from Arabic sources as well as the latest translations by Michael Scot of Aristotle and Avicenna on zoology. For example, he introduces to the West the Arab practice of hooding falcons, and he turns to Egyptian experts for an attempt to incubate ostrich eggs with the heat of the sun.25 Like Adelard, he has freed himself from the “halter” of authority; al-Emberor was more than prepared to correct no less an authority than Aristotle whenever his own observations or extensive experience with falcons demanded it.26 Frederick writes with the same note of intellectual self-confidence that would later prevail more broadly in the West: “Our work is to present things that are as they are.”27

  Few of his contemporaries were sympathetic to his scientific bent and reliance on reason. Pope Gregory IX, who battled Frederick for power and influence at every turn, bitterly accused the emperor of disregarding church teachings and, by extension
, papal authority by accepting only that which could be proved by rational thinking.28 Popular tales—some concocted by his many enemies, such as the thirteenth-century Franciscan monk Salimbene, who detested the emperor—cataloged Frederick’s supposed scientific excesses. One held that the monarch had ordered that infants be raised in total silence in an effort to learn whether they would grow up to speak Hebrew, thought of at the time as man’s “natural” language. In another episode, we are told, the emperor directed that a condemned man be allowed to suffocate in a sealed room, which was then opened carefully to see if his soul had escaped after death.

  Frederick was also a voracious reader, ready to take what he needed from scholars of different traditions or faiths, whether Muslim, Jewish, or Byzantine Christian, with an openness that clearly shocked the staid churchmen back in Rome. The fear of change that for centuries had effectively paralyzed the collective intellect of the Christian Middle Ages was remarkably absent in Frederick’s makeup.29 By his own account, he had been eager for knowledge since childhood, “inhaling tirelessly its sweet perfumes.” That same open and inquisitive nature, colored by a certain unbridled enthusiasm and scattershot quality of mind, informed the so-called Sicilian Questions, a rambling series of philosophical, metaphysical, and scientific questionnaires that Frederick enthusiastically forwarded to his large network of mostly Arab scholars. “Tell us … just where are hell, purgatory, and the heavenly paradise, whether under or on or above the earth?”30 Frederick asked his correspondents. Other topics had to do with optics—why did an object appear to bend when partly immersed in water?—and the size and structure of the universe.