The House of Wisdom

by Jonathan Lyons

  Euclid’s Elements was soon featured in the classrooms of the cathedral schools, most notably at Chartres, a leading center of education ever since the French monk and future pope Gerbert d’Aurillac returned from Spain with Arab-inspired learning to popularize mathematics and the other subjects of the quadrivium. This early affinity for Euclid at one of France’s greatest cathedrals proved of enormous practical and aesthetic value after a fire in 1145 forced the wholesale redesign and reconstruction of the massive structure. The extensive effort paid homage to Euclid, literally and figuratively: Decorative statuary dedicated to the seven liberal arts now included the Greek mathematician, while the architecture of the rebuilt cathedral demonstrated a new sophistication in the principles of geometry and proportion.47 The result is one of Christendom’s greatest architectural achievements.

  Already, European building and architecture had begun to show a marked technical improvement, as had the art of draftsmanship. This sudden upturn, as well as the appearance of specific skills and techniques not present earlier, dates to the direct transfer of practical technology from the master builders and masons of the East. In at least two well-known cases, Arab artisans arrived in the West and shared their knowledge. One, a Muslim known as Lalys, was captured in the Crusades and brought to England, where he eventually became court architect to King Henry I.48 In another instance, the Syrian chronicler Usama ibn Munqidh tells us, a stonemason who once worked for his family moved to the Christian lands and took his valuable skills with him. The Crusades also exposed Western craftsmen among the pilgrims and warriors to the latest Arab building techniques, while other tradesmen arrived in the West from Muslim Spain in the wake of the Christian military victories.

  Among the innovations derived from the Arabs was the introduction of the pointed arch, an integral feature of the new Gothic style of cathedral.49 Related technology allowed the remarkable vaulting that opened up these massive new cathedrals to the air—not unlike that of the modern greenhouse—and led to the construction of huge windows in what had in the past been massive unbroken walls. The reliance on the pointed arch in place of the semicircle between support pillars also gave the builders and architects greater flexibility, as they could now vary the distance between pillars without compromising or distorting the design.50

  Along with their high level of skill with technical drawings, the rules of proportion, and specific masonry techniques, the Muslim artisans offered a keen awareness of general geometric principles then unknown to the West. As a result, the traditionally irregular angles, crooked walls, and off-kilter doors and windows that made up much of twelfth-century European church architecture began to give way steadily to far greater precision in design and construction.51 The geometry of the Arabs, as popularized by Adelard, was soon adopted by the European master builders, the masons, as central to their craft. That “worthy clerk Euclid” became their guiding light. “Ye shall understand that among all the crafts of the world of man’s craft masonry hath the most notability and most part of the science of geometry,” proclaims a fourteenth-century guild document.52

  These innovative geometric techniques almost certainly formed the central core of the “secret” knowledge of the future Freemasons, around which so much legend still swirls. A notebook originally belonging to the twelfth-century French architect Villard de Honnecourt includes this typical reference to the practical uses of geometry: “It is thanks to geometry that the height of a building or the width of a river can be measured.” Villard’s compendium of geometric methods includes how to halve the area of a square, a necessary skill in the construction of pinnacles and other architectural features characteristic of the period.53

  Here, too, the Arab provenance of these new methods proved of great value, for the Muslim intellectual tradition was more than ready to use science to address practical questions. The masons and other artisans at work in the thirteenth century on the cathedral at Wells, not far from Adelard’s native town of Bath, were already using Arabic numerals to mark and identify components of the project, while their clients, the learned clerics, clung to the less supple Roman numerals in their account books for another four hundred years.54

  The sweeping importance of the restored Euclid was neatly complemented by Adelard’s other great revolutionary work, the translation of al-Khwarizmi’s star tables, the zij al-Sindhind. Adelard’s zij almost overwhelmed the West, for the tradition of the tabular handbooks reflected centuries of Muslim scientific advances and rested on mathematical assumptions that far exceeded anything Christendom had ever seen. An entirely new body of study, as well as a wholly new vocabulary, had to be developed in order for the West to comprehend the full scope and import of the zij. This process of assimilation occupied Latin scholars for hundreds of years, and it was not until the sixteenth century, with the arrival of Copernicus, that the West could field an equal to the classical Arab astronomers.55 Even the great Polish scientist could not have completed his groundbreaking work without the crucial aid of his Arab forerunners.

  Although the particular zij that Adelard transmitted to his fellow Latins around 1126 was obsolete by contemporary Arab standards, its own colorful history reveals the depth and breadth of science as fostered at the House of Wisdom and taken up elsewhere in the Muslim world. And it was more than enough to spur a flurry of activity among the West’s new scientists. The work itself consists of 116 tables, relying initially on Hindu teachings to catalog the movements of the sun, the moon, and the five visible planets. The tables are accompanied by thirty-seven brief chapters of explanation. Despite some basic errors in the translation of the Arabic text, the figures and tables are represented accurately, suggesting that Adelard understood the complex calculations, if not all of the linguistic niceties.56 He also continued his earlier practice, seen in the translation of Euclid and elsewhere, of sprinkling the text with Arabic words and phrases, highlighting important foreign terms, and providing useful explanations and other notations in the margins.

  A basic zij table, like the common astrolabe, is valid only for the specific locale for which it was designed. This was the source of considerable error and frustration among the early Western astronomers and mathematicians, for they first had to master the implications of the zij and then experiment with ways to update and adjust it properly before it could be of any real practical use. This same phenomenon allows modern researchers to work out, often quite precisely, where and when a specific zij was written or revised. In the case of the zij al-Sindhind, this record extends across thirteen hundred years of astronomical history, from the time of the Hindu scholars who provided the basis for the tables to our own.57

  Al-Khwarizmi used his base in the Abbasid capital, Baghdad, as the reference point for some of his calculations, and he relied on the Persian solar calendar common to his ancestral town, Khwarazm, on the Aral Sea. However, the Arabic version on which Adelard based his translation had been reworked significantly in the intervening three centuries. These tables reflect the meridian at Cordoba, in Muslim Spain, while the dates have been refashioned to fit the standard lunar calendar in use across the Islamic world. These revisions were the work of the eleventh-century Spanish mathematician Abul Qasim Maslama bin Ahmad, commonly called al-Majriti—meaning a native of Madrid—who added calendar conversions and various trigonometric and eclipse tables, as well as information designed for astrological calculations.58 The Spanish flavor of the zij raises the possibility that Adelard visited this former Muslim land, or perhaps nearby North Africa, during his seven-year grand tour. However, Adelard left behind no mention of such a trip, and it seems more likely that al-Majriti’s version fell into his hands elsewhere.

  In the late tenth century, the Umayyad caliph of Cordoba, al-Hakam II al-Mustansir, set out to challenge the intellectual supremacy of the rival Abbasids in Baghdad. The caliph assembled a huge collection of learned texts and attracted leading scholars to his kingdom of al-Andalus. Central to this effort was the work of al-Majriti and his followers, e
xperts in astronomy, mathematics, astrology, and the theory of the astrolabe.59 “Abulqasim Maslama bin Ahmad, known by the name al-Majriti, … was the chief mathematician in al-Andalus during his time and better than all the astronomers who came before him. He was extremely interested in astronomical observations and very fond of studying and understanding the book of Ptolemy known as the Almagest. He wrote a good book … [on] the mathematics of business transactions,”’ records the medieval chronicler Said al-Andalusi. “He also worked on the zij of Muhammad bin Musa al-Khwarizmi and changed the dates from the Persian to the Hijra [Islamic] calendar … but he followed al-Khwarizmi even when he was in error without indicating the areas where such errors were committed.”60

  Al-Majriti’s reworking of the zij al-Sindhind must have proved irresistible to Adelard, for it combined the Arab mathematical astronomy with the study of astrology and the technology of the astrolabe—all subjects near to the Englishman’s heart. Before setting foot in the Muslim world, Adelard wrote in On the Same and the Different of his passion for astronomy, above all the other “maidens” of the seven liberal arts: “This maiden whom you see standing before you with splendor … sketches the shape of the world, as contained in her teaching, the number and size of the circles, the distance of the orbs, the course of the planets, the positions of the signs of the zodiac; she paints in the parallels and colures, she divides the zodiac into twelve parts with thoughtful reason, she is aware of the size of the stars, the opposite positions of the two poles, the axis stretching between them.”61

  The same early work also hints at Adelard’s coming love for the Arab science of astrology—that is, for the study of the celestial bodies for clues to events here on earth. “If anyone could make her [astronomy] his own, he would be confident in declaring not only the present condition of lower things, but also their past or future conditions. For, those higher and divine animate beings are the principles and causes of the lower natures.”62 When Adelard first wrote those words, he was still a long way from mastery of the tools and techniques of astronomy. Now, fifteen or twenty years later, his Arab star tables, illuminated by Euclid’s Elements, could begin to fill in the significant gaps in his understanding and knowledge.

  Even before Adelard introduced the zij tables and offered a glimpse of the Arab mathematical astronomy that lay behind them, scattered pockets of scientific activity dotted the Western intellectual landscape. The scholar-monks of Catalonia, which bordered on the Muslim lands, had partly assimilated the astrolabe texts of al-Majriti and his colleagues. Gerbert d’Aurillac had successfully popularized elements of the quadrivium at the French cathedral schools. And Adelard’s hometown and the nearby monasteries of the Severn basin played host to a lively circle of mathematicians and astronomers, mostly Lotharingians and all trying to make sense of the early teachings trickling in from the Muslim world. There was even a failed attempt to introduce the zij al-Sindhind to Latin readers, a development that may ultimately have compelled Adelard to produce his own, successful translation of al-Khwarizmi.63 It is no wonder that in 1138 the annalist John of Worcester took great pride in the fact that he had helped copy the treasured star tables at the Worcester Cathedral priory, seventy-five miles north of Bath: “I set down here the first month of the Arabic year and the day and hour with which it began so that the work which in Arabic is called ‘Ezich’ and which the learned Elkaurexmus [al-Khwarizmi] wrote most carefully on the course of the seven planets, and laid out in tables, is not consigned to oblivion.”64

  At first the explicit conjunction of astronomy and astrology that characterized many of the first Arabic texts to appear in Latin attracted little notice in the West. However, the use of astrology to forecast coming events soon caught the attention of Christian orthodoxy, for the relationship between the heavenly bodies and events here on earth had much in common with both magic, the realm of the sorcerer, and theology, the realm of the priest. The Muslim world had already begun to experience a backlash, with some of the luminaries of Arab thought lining up to challenge astrology and its prediction of the future as un-Islamic. Likewise, the Christian theologian John of Salisbury denounced the work of the “mathematici,” or astrologers, as antithetical to morality and incompatible with both man’s free will and God’s unquestioned omnipotence. “He—the astrologer—decks out the years with a kaleidoscope of things to come, as though he were painting a fresco; and he winds a rope of future events through the flying wheel of time … [But] … the will of God is the first cause of all things, and mathesis is the way of damnation,” John thunders in his Policraticus.65 As in the Arab world, the Latin astrologers largely carried on with their art unimpeded.

  Such difficult, technical works as Euclid’s Elements and the zij of al-Khwarizmi reflect the mature scholarship of Adelard, after years of immersion in Arab learning. The surviving examples of the geometry text and the star tables were completed after his return to England and may have been intended for use as textbooks or study guides by Adelard’s students and other budding scholars. But Adelard also left behind his accessible and highly readable essay Questions on Natural Science, in which he sets out to encapsulate the spirit of learning and inquiry he found in the East—framing the text as a response to his pushy nephew’s demand for some “new ideas” from the studia Arabum.

  The topics begin with the vegetable and animal kingdoms and proceed to the moon and stars overhead, before bumping up against the delicate question of God’s very existence. Chapter 7 addresses the question of “why some brute animals chew the cud, but others do not.” Chapter 19 explains “why the nose is placed above the mouth,” while Chapter 58 answers what has since become a classic question of elementary physics: why water does not flow out from a narrow vessel with holes at the top and bottom if the upper opening is covered with the thumb. Likewise, Adelard understands the concept of the conservation of matter: “And in my judgment certainly, nothing at all dies in this sensible world, nor is it smaller today than when it was created. For if any part is released from one conjunction, it does not perish but passes over to another association.”66 Adelard then goes on to explain the mysteries of lightning and thunder, the moon’s apparent lack of light, and whether the stars are animate and, if they are, what they might eat—“the moistures of the earth and the waters, thinned by the very long distance they travel when they are drawn up to the higher regions.”67

  Finally, the nephew touches on the problematic question of God’s existence: “From you, then, I want to hear, using reason alone and keeping away from the flattery of authority, whether he exists or not, and what he is, and what he does.”68 Already, Adelard has exhibited a certain wariness about advancing views that might be unwelcome to Western ears. He often hides behind the opinions of “the Arabs” to express what may well have been his own views on man, nature, and the universe. “No one should think I am doing this out of my own head but that I am giving the views of the studies of the Arabs … For I know what those who profess the truth suffer at the hands of the vulgar crows. Therefore, I shall defend the cause of the Arabs, not my own.”69

  Faced with his nephew’s persistence, Adelard stalls for time, pointing out that he is more accustomed to dispelling what is false than to proving what is true. Then he suggests that any such discussion of God would exceed all others in the “subtlety of its intellectual content and the difficulty of its expression.”70 Wisely, he notes that the hour is late and it is time for bed, promising to take up the matter of the “beginning of the beginnings” at a later date. Somehow, that day never comes.

  The preservation over the centuries of many of Adelard’s works bespeaks their popularity and importance in their day. Still, the absolute numbers are small, in keeping with both the low level of “book culture” at the time and the many practical obstacles to the dissemination and storage of information. The simple survival of a medieval text is no mean feat, for each one had to be laboriously copied by hand onto stiff sheets of parchment, which in the West was generally done ov
er many months by professional scribes in monasteries scattered across the Latin-speaking world. For every one that has come down to us today, there must have been many others that were lost; were damaged by fire, vermin, or other hazards; or simply fell into disfavor and were no longer given priority within the limited confines of the medieval monastic scriptoria.

  Early copies of Adelard’s Questions on Natural Science were made both in his native England and on the European continent. Thirteen examples from the twelfth century are extant, a number of which were produced in small, portable editions for ease of use and study. Ten others survive from the thirteenth century, but just three from the fourteenth and two from the fifteenth, suggesting a decline in popularity as other texts came to the fore. However, the work later enjoyed a brief revival, especially in Adelard’s native England. Editions were also produced in Hebrew and quite possibly in French, while large sections were translated into Italian.71 Dozens of the early Latin Euclid texts have been found, as have nine copies—but only two complete ones—of Adelard’s translation of the star tables of al-Khwarizmi.72

  Adelard’s greatest achievement, however, lay less with his individual manuscripts than with his intuitive grasp of the broad significance of Arab teachings just beginning to penetrate Christian consciousness. This strand runs through Questions on Natural Science, which features such phrases as “my Arab masters” and “the cause of the Arabs.” Unlike the handful of intellectual explorers who came before him, Adelard was not content simply to borrow the outer trappings of new ideas and technologies. Instead, he sought to reinvent himself and the very idea of the West in accordance with Arab learning. At its core was the proposition that experimentation, rational thought, and personal experience trumped convention and blind acceptance of traditional authority. Adelard seemed to realize that in order to absorb and exploit these great discoveries, he had to do more than simply master Arabic; he had to jettison almost everything he thought he knew and adopt a whole new way of looking at the world around him.73 “If you wish to hear anything more from me, give and receive reason. For I am not the kind of man for whom the painting of the skin can satisfy. Every letter is a prostitute, open now to these affections, now to those,” he lectures his nephew.74