The House of Wisdom (20 page)

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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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, experts in astronomy, mathematics, astrology, and the theory of the astrolabe.
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“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.”
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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.”
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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.”
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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.
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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.”
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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
.
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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
.