NO ONE KNOWS where Adelard learned Arabic—perhaps in Syracuse, on the once-Muslim island of Sicily, perhaps only later in Antioch itself. Before setting out for the East, he had asserted the common medieval notion that completely mastering the subject of grammar would ultimately give the reader access to any text in any tongue. He also noted the advantages of studying individual languages, suggesting he was well prepared to succeed at such an undertaking himself.1 Adelard tells us that he spent approximately seven years in and around the crusader lands able to communicate effectively with local scholars, something that would have required considerable facility with Arabic. Along the way, he mentions various Arab mentors who guided him in his research, and he worries aloud whether he may have attended so many lectures that they have blunted his memory. Among his teachers was a master of anatomy, an “old man of Tarsus,” in southern Asia Minor, not far from Antioch. His instructor, an adept at advanced Arab medicine, taught him sophisticated dissection techniques, including how to immerse a cadaver in running water to gently wear away the soft flesh and expose the body’s intricate networks of blood vessels and nerves.
The path Adelard traced to Antioch is almost as obscure as the course of his language studies. He provides only a handful of clues about his wanderings in search of the studia Arabum, leaving much to be reconstructed from scattered hints in his books and translations and a few obscure references from fellow scholars. In 1109, Adelard deposited his nephew and other students then in his charge at Laon, where he left them to the “insecurity of French opinions.” Almost immediately the trail goes cold, until he resurfaces five years later in the principality of Antioch, huddled on the “trembling bridge” at Mamistra during the earthquake. Given his earlier visit to the archbishop of Syracuse, memorialized in On the Same and the Different, it seems likely that he returned to Sicily and used it as his jumping-off point to the East. The island was linked to Antioch by close family ties between their respective Norman rulers, making communications, travel, and trade relatively easy.
At the time, Antioch was just beginning to emerge as an important center for the translation of Arabic texts into Latin, particularly in the field of medicine, where Muslim science was second to none. Traders from the Italian city-state of Pisa, who had earlier helped ferry the crusaders to the Holy Land in exchange for booty and territory, now wielded enormous influence in Antioch. They controlled their own quarter in the very center of the city and the whole of the nearby port of Latakia. As a result of these and other commercial and political links around the eastern Mediterranean, Pisa found itself to be a vital hub in the spread of Arab wisdom. Arabic texts seized by conquering Christian armies around the region swelled the book bazaars, transforming the city into something of an entrepôt of Muslim science. Antioch’s Pisan quarter bordered on the monastery of St. Paul, a Benedictine institution that surely would have welcomed Adelard, whose father, Fastrad, and mentor, Bishop John, were both prominent members of the same order back in Bath.
Like Adelard, the Italian translator and scholar Stephen of Pisa—sometimes known as Stephen the Philosopher—soon made his way to Antioch to learn from the Muslims. There he translated a prominent medical encyclopedia, The Royal Book, by Ali ibn al-Abbas al-Majusi, known in the West as Haly Abbas. This work, dating from the tenth century and comprising ten chapters on medical theory and another ten chapters on clinical practice, was already widely used across the Muslim world. Stephen’s Latin version quickly became a European standard as well. Stephen begins chapter eight, on medical practice, with a personal note: “… The translation from Arabic into Latin of Stephen the disciple of philosophy. He wrote the copy himself and completed it in the year from the passion of our Lord 1127, on Saturday, November the third, at Antioch. Thanks be to God, the beginning and end of things.”2
To accompany the text, Stephen fashioned his own glossary of Arabic and Greek medical terms, with some Latin equivalents—a work so valuable that it was meticulously copied and recopied by hand in the West for hundreds of years and even printed centuries later, during the Renaissance. Stephen himself was apparently less impressed with his own handiwork; he was not a physician and instead considered himself a “disciple of philosophy.” Next time, he promises, he will translate something from among “all the secrets of philosophy that lie hidden in the Arabic tongue.”3 Medicine, he notes, is but the lowest rung of the philosopher’s art, but one has to begin with the needs of the body before addressing the improvement of the soul.4
While Stephen at first concentrated on matters of the lowly human body, Adelard reached for the heavens. As a young student in France, he had confidently predicted that the knowledge available in the Arab East could help cure the ills of the West—a decidedly unorthodox view in the era of the anti-Muslim Crusades. But not even Adelard could have anticipated what he would find in the studia Arabum. Among his trophies were the geometric system of Euclid; an elaborate Arab table of the movements of the stars; techniques for using that powerful computer, the astrolabe; several major works of Arab astrology; and a book of alchemy revealing ways to dye leather, tint glass, and produce green pigment—Adelard’s favorite color. The man from Bath plunged headfirst into the world of astronomy, philosophy, and magic.
In all, about a dozen surviving works can be traced directly to the restless Englishman. The scope of his interests is breathtaking, from the royal art of falconry to applied chemistry, from geometry to mathematical astronomy and cosmology—the text often written in the accessible style of the natural-born teacher and raconteur. Adelard’s works also offer a useful window onto the state of Western borrowings from the Arabs, for his original works can be neatly broken down into those completed before his intellectual encounter with the East and those that followed it.
Upon his return to Bath, Adelard found himself besieged by friends and family, all eager to learn of his seven years abroad. “Among those paying their calls was a certain nephew of mine, who, in investigating the causes of things, was tying them in knots rather than unraveling them. He urged me to put forward some new item of the studies of the Arabs,” Adelard recounts.5 The result is Questions on Natural Science, a series of queries and responses on what the classical authors call natural philosophy. The Western-educated nephew does the asking, and the learned Adelard, this time speaking for the Arabs, responds. “This is how the causes of things work,” the well-traveled scholar declares at the outset, in what might serve as the motto for his long career as a scientist and scholar. “So let us start from the lowest objects and end with the highest.”6
Among the first Arabic texts to capture Adelard’s imagination was a classic work on tilasm, or the art of “talismans”—elaborate charms thought to invoke celestial influence—horoscopes, and astrological images by Thabit ibn Qurra, one of the leading lights of medieval science. Thabit ibn Qurra was a member of the star-worshipping Sabean sect, whose religious practices engendered a close affinity for astronomy, astrology, and mathematics. The Sabeans were also well grounded in Greek philosophy. According to Arab tradition, Thabit was a former money changer in the bazaars of Harran, with an impressive facility for languages. He caught the eye of a prominent Baghdad aristocrat and scholar, who arranged for him to study and work at the House of Wisdom. While the Sabeans were viewed with suspicion by many Muslims, the sect’s advanced Greek learning and invaluable skills afforded them a considerable measure of influence and status during the early Abbasid years.
The talented Thabit flourished in the learned environs of Baghdad, and he went on to serve as royal astrologer in the late ninth century. One of the empire’s great scholars and linguists, Thabit revised and corrected Arabic versions of the Almagest and other Greek classics and produced original works on number theory, calculus, and mechanics. He also wrote several texts on the philosophical and religious views of his fellow Sabeans and was regarded among the Arab scholars as an expert on talismans.7 In the preface to his own translation of Thabit’s text on magic, the twelfth-century Latin scholar John of Seville suggests that Adelard, the only other Westerner to have seen the original Arabic work, procured a copy while in Antioch: “This book, then, I, with the help of God’s spirit, obtained from my Master—a book which no Latin other than a certain Antiochene, who once obtained a part of it, ever had.” That “certain Antiochene” is none other than Adelard of Bath, who earlier published an abridged version of the same text.8
Where others feared the influence of Saracen sorcery, Adelard celebrated the notion that man might aspire to understand and even conquer nature. He also directly linked the practice of magic to other scientific endeavors, noting that the study of talismans first requires the mastery of astronomy and astrology. “Whoever is skilled in geometry and philosophy but without experience of the science of the stars is useless; for the science of the stars is, of all the arts, both the most excellent in its subject matter and the most useful because of the effects of talismans,” Adelard tells us in his own version of Thabit ibn Qurra’s work.9 The text, known as The Book of Talismans, includes incantations for driving away mice and techniques for rekindling love between husband and wife. There is even a talisman for ridding a town of scorpions. First, an image of a scorpion is fashioned from metal while Scorpio is in the ascendant. Next, the name of this constellation and other astronomical details are inscribed on the talisman. Finally, it is buried in the place to be protected—or better yet, in all four corners of the place—while one recites, “This is the burial of it and of its species, that it may not come to that one and to that place.”10
Adelard leavened his translation with a liberal use of Arabic phrases, giving it a mysterious appeal in a Latin world starved for both novelty and basic information. In the prescription for a wife seeking to regain her husband’s affections, he spells out the required incantation: “O fount of honor, joy and light of the world! Mix together the loves of these two people, o spirits, using your knowledge of mixing, and being helped toward this end by the greatest power and the might of al-malik al-quddus wa al-hayah al-da ’ima” an Arabic phrase that Adelard translates as “the king, the holy and eternal life.”11 This noble appeal to God or his intercessors, not to demons, is in keeping with Islamic tradition and sets it apart from the notion of black magic in Christian Europe.12 At one point, Adelard gives us a rare hint as to what might have compelled a young man from the English West Country to push deep into uncharted intellectual territory, alone in a strange and distant land. The practitioner of magic, he writes, must remain focused on the task at hand, and he should always act with confidence. For “lack of hope is the mother of hesitation, and hesitation is the mother of ineffectiveness.”13
Under the influence of Thabit ibn Qurra and other such thinkers, Adelard developed a lifelong fascination with the occult as part and parcel of his science. As far as many of the Muslim scholars were concerned, astrology and magic fit right in with astronomy, medicine, chemistry, and weather forecasting, a convention that Adelard did much to popularize among early Western scientists. Arab doctors, for example, routinely consulted the stars to identify the best time to draw blood or conduct surgery, matching parts of a patient’s body with an astrological map of the heavens. This system was first propagated by ancient Greek medical practice: Aries was associated with the head, and one continued down the body and around the signs of the zodiac to Pisces, which corresponded to the feet.14 The University of Bologna, one of the medieval West’s great centers of medical training, had a special master dedicated to teaching future doctors how to assess the influence of the stars on the human body.15
Adelard, it seems, also dabbled in alchemy, an important incubator of early experimental science and the forerunner to modern chemistry. Although its origins lay in the philosophical investigation into the nature of substance and reality, much of medieval alchemy came more and more to comprise specific techniques for manipulating materials with solvents and reactive agents or creating metal alloys and dyes, all basic processes that would one day find a home in the chemist’s laboratory. Today, the word alchemy mostly conjures up the secretive, even mystical, pursuit of ways to create gold from lesser metals. One surviving medieval reference ascribes to Adelard a lost twelfth-century manuscript of alchemical recipes and techniques, known as A Little Key to Drawing. An extant version—without attribution to Adelard or anyone else—features a series of instructions for refining gold and silver, working in precious metals, tinting glass, and coloring leather, many dating back to the alchemical traditions of Hellenistic Egypt. In all, it presents 382 chapters, or recipes, about one third of which appear to be relatively recent additions.16 One salient feature of A Little Key to Drawing is its complete lack of reliance on Latin sources for the central material—there is, for example, no hint of the canonical works of Vitruvius in its architectural sections—making it one of the earliest examples of technology transfer to the Christian West.17
A number of clues suggest that Adelard may have augmented the older core text based on his own research and personal interests. These hints include a reliance on Arabic terminology similar to that found in his translation of Thabit, The Book of Talismans; the introduction into the Latin text of two English words in a section on techniques for producing green pigment, a color Adelard adopted as his trademark; a pair of recipes for making candy from sugarcane, a plant unknown at the time in northern Europe but familiar to one who had traveled as widely as he had done; and, finally, some passages that mirror text from Adelard’s known writings, including his earliest work, On the Same and the Different. 18
The alchemical manuscript’s innocuous title may have been selected to obscure its true contents from casual curiosity, for A Little Key to Drawing is a gold mine of medieval technology, containing the industrial secrets of contemporary artisans making glass, leather, and other products, as well as the fundamental techniques and methods of early Western science.19 Among its treasures is a recipe, written in code, for the distillation of alcohol—a key ingredient in many alchemical procedures. Such works reveal a great deal about the underlying state of knowledge passed along by the Arab masters of the day, for the art of Muslim alchemy was dedicated, in part, to the search for pure “essences” through distillation, crystallization, reduction, and other fundamental chemical processes. Arab authorities on the subject taught that mixing particular distillates together could create a rarefied substance, the elixir, capable of curing disease, purifying lesser materials, and even prolonging life. This was later known in Europe as the fifth essence—the source, literally, of our word quintessence—and was a complement to the classical Greek schema of the four basic elements: air, water, earth, and fire.
The great ninth-century Arab alchemist Jabir ibn Hayyan taught that each of the earth’s metals consisted of different mixtures of sulfur and mercury, allowing for the possibility that they could be “transmuted” if one broke them down into these two intermediate elements and then rearranged the proportions and relative purities. This provided a theoretical basis for many of the alchemists’ early scientific investigations, a search that proved equally popular in the East and the West—not least for the expectation that one could ultimately produce gold from more common, base metals.20 Jabir, known in Latin as Gaber, to whom countless European alchemical texts were later spuriously ascribed, was closely associated with Shi’ite and mystical Sufi teachings, and his alchemical practice mirrored those sects’ spiritual quest to penetrate natural phenomena and reach the inner, revealed meaning. Here, then, was the philosophical basis for the now-discredited art of alchemy, and any change in material substance in the laboratory was, for Gaber and his like-minded colleagues, symbolic of a transformation of the soul.21
In the hands of some later Arab alchemists, this vital symbolic component was gradually stripped away, easing the transition from the spiritual discipline of alchemy to the practical science of chemistry. The works of such scientists covered the classification of mineral substances, basic processes and techniques, and discussions of apparatuses and other equipment—all easily assimilated into an emerging Western scientific language.22 The arrival in the Latin world of Arab alchemy stimulated centuries of research into chemical properties and experimental procedures, very much as the geocentric worldview contained in Arabic studies of the Almagest helped push back the boundaries of mathematical astronomy. The thirteenth-century English scientist and philosopher Roger Bacon, who shared Adelard’s enthusiasm for magic, saw great promise in what he termed a practical approach to the discipline: “But there is another alchemy, operative and practical, which teaches how to make the noble metals and colors and many other things better and more by art than they are made in nature. And science of this kind is greater than all those proceeding because it produces greater utilities.”23
The politics of alchemy also played an important role in the rise of Western science, for requirements of state at times afforded its early practitioners invaluable protection against the condemnation of religion. In this way, it mirrored the development of astrology, which also had its many religious critics in both the East and the West. The princes of Europe were eager to bolster their flagging coffers by employing, in the words of one English monarch, “men learned in natural philosophy” to increase the royal holdings of gold coins through the practice of alchemy.24 In reality, the best the alchemists managed to do was devalue the crown’s currency through the stealthy introduction of impurities that swelled the number of coins but diluted their actual gold content. This technique was not unlike a modern paper-money economy’s simply printing new currency to cover its mounting expenditures. The forces of the church, who stood to lose power and influence at the hands of secular kingdoms so “enriched,” denounced the practitioners of these arts as charlatans. The popes and their allies also invoked church teachings to warn against interference by man in God’s natural order. “They promise that which they do not produce,” complained Pope John XII, in a papal bull of 1317.25
The earliest mention of A Little Key to Drawing is contained in a ninth-century library catalog from the Benedictine monastery on Reichenau, in Germany, but the lost manuscript to which it refers would have been older still.26 Clearly, European artisans had mastered and preserved some important industrial techniques throughout the turmoil of the early Middle Ages. This, however, did not blunt the enormous impact of the arrival of Arab alchemy and early chemistry beginning in the twelfth century, introduced by the likes of Adelard. Within a few short decades, his fellow Englishman Robert of Ketton produced the first full Latin text on the Arab art, The Book of the Composition of Alchemy. “Since what Alchemiya is, and what its composition is, your Latin world does not yet know, I will explain in the present book,” Robert promises his readers in the preface.27
Soon a flood of translated Arab alchemical works began to pervade the West, threatening to overturn Christendom’s traditional relationship between man and nature and prompting vigorous philosophical and theological debate about the use and abuse of technology.28 Spurred on by the arrival of these Arab teachings, the Latin alchemists were among the earliest pioneers in the West’s discovery of the natural world, while their theories of nature, such as that on the composition of matter, would contribute to the scientific revolution of the sixteenth and seventeenth centuries.29
Long before Adelard arrived in Antioch, ignorance, disorder, and self-imposed religious isolationism had cut the West off from centuries of scientific and philosophical advances. The natural world was largely unquestioned and unexplored, and early attempts to penetrate its mysteries often aroused suspicions of sorcery or the mischief of demons. With little or no grasp of physical laws that might explain the spread of deadly disease, for example, or illuminate the arts of navigation or telling time, medieval Christendom tended to see the universe as a dark and frightful place. Superstition ruled the day. In short, there was no method, only a sort of mania or madness—as witnessed by the widespread claim of apocalyptic visionaries on the popular imagination and extravagant explanations of natural phenomena. All that began to change with Adelard’s discovery of one of the greatest scientific works in history, the mathematical system of Euclidean geometry.
The thirteen books of Euclid, known as Elements, include six chapters on basic geometry, three on number theory, and a single section on “incommensurables”—what are known today as irrational numbers. The side and the diagonal of a square represent the most familiar example of incommensurable numbers. There is no single unit that can measure both lines; thus, their relationship cannot be written as a fraction or ratio. It has been suggested that the problem of incommensurables forced the Greek philosophers to discard the notion that the universe could be described fully in terms of positive whole numbers and to concentrate instead on developing geometry as a more accurate and useful representation of physical reality.30 The final three chapters of Elements are devoted to solid geometry.
Euclid’s own life and origins are obscure and subject to much speculation, although it is known that he founded a school in Alexandria, where he flourished around 300 B.C. His masterwork represents a collection and reworking of much of Greek mathematics to date, presented in a compelling, logical format. Euclid begins by introducing the basic building blocks of geometry and then spells out a problem to be solved. Next, a proposed solution is presented. Finally, the proof reasons from the earlier propositions, or axioms, to establish the truth of the construction, and the conclusion confirms that the problem has been solved satisfactorily within the agreed rules of the game. Each successful demonstration forms part of the basis for later, more sophisticated problems.
Taken together, the thirteen books of Elements offer a comprehensive logical system and an introduction to deductive reasoning, essential to the development of the scientific method and rational philosophical inquiry. Yet medieval Europe knew almost nothing of Euclid’s science, except some poorly understood fragments preserved by Boethius and a few of the other Latin encyclopedists. Isidore of Seville, for example, devoted a total of just four pages of his Etymologies to the subjects of geometry, arithmetic, music, and astronomy combined.31 Such scraps afforded Christian scholars no glimpse of the intellectual riches contained in Euclid’s Elements.
Euclid fared far better at the hands of the Arabs, who recognized his importance and made the mastery of Elements, along with the Almagest, the techniques of Hindu astronomy, and the natural philosophy of Aristotle, a cornerstone of their intellectual enterprise. It is worth noting that Arab scholars also identified the most serious shortcoming of the Euclidean system, the fifth postulate, which advances the notion that parallel lines can never intersect even as they extend to infinity. The essence of the problem lies with asserting the behavior of such lines outside human experience, and Euclid himself seems to have expressed some doubts about this aspect of his own work. All attempts to date to establish this rule as absolute have failed. However, the medieval Arab mathematicians repeatedly attacked the problem over the centuries in new and creative ways—work that eventually found its way to the West, where it later influenced a number of leading mathematicians.32
Caliph al-Mansur invoked Euclid’s teachings in the geometric design of his Round City, and his successors ensured that Elements was one of the first major Greek texts translated into Arabic. The works of two Abbasid scholars on Elements have survived to this day. The first scholar, al-Hajjaj, completed a full translation and an abridgment, the latter at the direct request of Caliph al-Mamun. A second, later version, one that more effectively tracks the Greek original, was edited and revised by Thabit ibn Qurra, the researcher at the caliph’s House of Wisdom whose Book of Talismans Adelard translated.33
The Arabs also produced dozens of commentaries on Elements and translated other important works by Euclid. Almost immediately, the Muslim approach to both science and philosophy began to reflect the Greek mathematician’s fundamental insistence on demonstrable proofs. This approach soon extended to questions of theology and religion, prompting the aristocratic scholar al-Kindi to seek out the teachings of Greek philosophers on metaphysics in order to subject matters of faith to this same form of rigorous analysis. Toward this end, al-Kindi commissioned Arabic translations of Greek philosophical texts that would one day pose a major challenge to the theologians of both the East and the West, including Aristotle’s works on cosmology and the soul.34
For medieval Europe, the discovery of the complete Euclid was a sensation. The three earliest Latin versions, based on the translation of al-Hajjaj three centuries earlier, have historically been attributed to Adelard.35 Editions by other scholars soon followed. Notations in a number of surviving manuscripts and the testimony of later medieval intellectuals establish Adelard’s close links to the earliest texts. Roger Bacon quotes from the third of these treatises—actually a commentary on Euclid rather than a translation—and refers to it approvingly as the “special edition of Adelard of Bath.”36 And there is no reason to doubt Adelard’s own account when he tells us in a later work that he already translated Elements some years before.37
No one has yet succeeded in unraveling the mystery of exactly which texts bear the master’s own hand. Still, Adelard’s fingerprints are all over the successful introduction of Euclidean geometry to the Latin world, as early as 1126. Whatever their exact provenance, these first manuscripts reveal much about the ways in which Adelard and the early Latin scholars who followed in his path assimilated and gradually mastered Arabic scientific texts. The oldest editions bear all the hallmarks of an early, tentative encounter with the studia Arabum. The translation of technical terms is often inconsistent and relies heavily on imprecise or erroneous Latin terms; at other times, failing to find any Latin equivalent, the author simply transliterates from the original Arabic. Such linguistic poverty was soon to plague the translations of Muslim philosophy as well; one early version of a major work of Arab metaphysics is forced to fall back on a single Latin word, esse, to represent thirty-four distinct Arabic expressions for being and related notions.38
According to a modern linguistic analysis, the earliest translation relies on more than seventy direct transliterations from the Arabic in order to present basic geometric concepts for which medieval Latin had no ready terminology. These include diameter, tangent, and ratio. However, a slightly later version has reduced its reliance on Arabic to fewer than two dozen transliterations and has replaced all of the terms above with suitable Latin equivalents. This suggests that Adelard—or perhaps a colleague or one of his pupils—had since made considerable strides in mastering the material at hand and identifying or producing Latin variants.39 Some of the extant Euclid manuscripts also include marginal notations discussing Arabic vocabulary or explaining points of grammar, a technique that Adelard himself used in other works—in one, he highlights the foreign words in special red ink—and one that was carried on by his students.40
Virtually all surviving examples of the second of the three early Latin Euclids explicitly identify the work as that of Adelard. This version proved a “bestseller” for five centuries and formed one of the centerpieces of the West’s emerging new sciences. At least fifty-six manuscripts have survived, a relatively large figure that attests to the work’s general appeal and widespread use.41 It served as the basis for what later became the definitive scholarly text of the day and was cited widely in commentaries throughout the thirteenth and fourteenth centuries. In the realm of theory, Euclid gave the Latins their first explicit model of scientific thinking and exposed them to the classical approach to logical deduction.42 In practical terms, his geometry was crucial to the development of medieval astronomy, for it allowed the measurement of far-off celestial bodies in terms of angles and degrees and helped explain and predict their movements through the heavens.
These first Latin translations, which sought to interpret Euclid for a Western audience, set the stage for the rigorous Arabic program of study that culminated in mathematical astronomy and applied astrology.43 They also had a profound effect on the overall development of early European scientific and philosophical thinking. Robert Grosseteste—literally “the big-headed,” prompting one contemporary to call him “Robert of the big head but subtle intellect”44—recognized the fundamental importance of the new geometry. “The utility of a consideration of lines, angles and figures is the very greatest, since it is impossible that natural philosophy be known without them. They obtain absolutely in the whole universe and in its parts,” writes Robert, an early chancellor at Oxford, who died in 1253. Without lines, angles, and figures, he notes, it would be impossible to know the true nature of things.45
Roger Bacon, Robert’s younger colleague, repeatedly invokes Adelard’s special edition of Euclid as an authority for the idea, just beginning to take root in the West, of the uses of proof in both logic and the theory of knowledge, or epistemology. Roger draws explicitly on Adelard for his own groundbreaking work on theories of vision and on the broader question of the role of experimentation in science. “An axiom, as Adelard of Bath says in his edition, is interpreted as a dignity, for it explicates the definitions of things. And this is especially true when the axiom is taken strictly, although in a wide sense all principles are called axioms, as Adelard of Bath’s epilogue at the end of the book supposes,” Roger writes in his Geometrica Speculativa.
He then goes on to link Adelard directly to Aristotle’s own work on experience and experimentation, before adding, “A postulate is, as Adelard of Bath says, that which being conceded nothing inconvenient follows from the hypothesis.” The union of these three elements—geometry; the system of axioms, postulates, and proofs explained by Adelard; and direct experience—formed the basis for much productive Western research and scholarship, including the development at Oxford of calculus and formal analysis.46 The new art of geometry was also central to medieval philosophical investigation into light, color, and vision.
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, experts 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 over 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
As for the crusaders who preceded Adelard to Syria, the overwhelming majority were too blinded by ignorance and sectarian hatred, or by their own moral smugness, to recognize the accomplishments of the advanced civilization they now faced in battle. This tendency is reminiscent of the present day, when the West looks eastward and sees only barbarism. Adelard’s outlook proved a remarkable exception to the mood of his own times—which held that Islam was an evil faith with nothing to offer Christendom but the role of sacred enemy—and he came back to England very much a new man. Everything that was once familiar in his native land now appeared part of an alien and distasteful world.
Upon the insistence of friends and family, with whom he had just reunited, Adelard surveyed the state of English society. “I found,” he writes in Questions on Natural Science, shortly after his return home, “the princes barbarous, the bishops bibulous, judges bribable, patrons unreliable, clients sycophants, promisers liars, friends envious, and almost everybody full of ambition.”75 Ever the teacher, Adelard resolves that knowledge offers the best antidote to the “moral depravity” on display in his homeland. “I undertook the following treatise, which I know will be useful to its auditors, but whether it is pleasant, I do not know. For the present generation suffers from this ingrained fault, that it thinks that nothing should be accepted which is discovered by the ‘moderns.’ ”76
During his wanderings, Adelard tells us, he adopted his trademark flowing green cloak and began to sport a prominent signet ring, set with an obscure astrological symbol, in the same rich green, “less extensive but more efficacious” in its emerald hue. Adelard’s new intellectual outlook is no less startling. Gone is the young country gentleman who once dedicated earnest prose to the goddess of philosophy, in pale imitation of the bygone classical age; in his place stands the relentless seeker of knowledge and scientific truth. The new Adelard, now a citizen of the world, challenges the intellectual corruption, complacency, and rigidity that has dogged the West for centuries. Unlike the student from the cathedral schools who once branded the moderns “dumb,”the reborn Adelard is an ardent proponent of contemporary scholarship—only now his world is shaped by the new and dynamic Arab learning from the East.
Such knowledge, he says, can liberate the Western world from the burden of orthodoxy and give man permission to make his own way through the universe: “For I have learned one thing from my Arab masters, with reason as guide, but you another: you follow a halter, being enthralled by the picture of authority. For what else can authority be called other than a halter? As brute animals are led wherever one pleases by a halter, but do not know where or why they are led, and only follow the rope by which they are held, so the authority of written words leads not a few of you into danger, since you are enthralled and bound by brutish credulity.”77
Man should take refuge in God, he declares, only when his intellect proves incapable of understanding the world around him. Such a declaration connects Adelard of Bath directly to his spiritual and intellectual heir, the pioneering astronomer Galileo, whose public showdown with religious orthodoxy five centuries later would seal the end of the beginning of the Western scientific revolution. This wanderer in the flowing green robes issues the first explicit assertion in the Christian Middle Ages that the existence of God must not prevent man from exploring the laws of nature. “I will detract nothing from God, for whatever is, is from Him … We must listen to the very limits of human knowledge and only when this utterly breaks down should we refer things to God.”78