MOST OF THE GREEK PHILOSOPHICAL AND SCIENTIFIC WORKS that survived made their way through the Hellenized Syriac-speaking Christians of Mesopotamia to the Islamic world after 762, when the Abbasid caliph al-Mansur founded Baghdad as his new capital.
Baghdad emerged as a great cultural center under al-Mansur (r. 754–775) and three generations of his successors, particularly al-Mahdi (r. 775–785), Harun al-Rashid (r. 786–809), and al-Ma’mun (r. 813–833). According to the historian al-Mas’udi (d. 956), al-Mansur “was the first caliph to have books translated from foreign languages into Arabic,” including “books by Aristotle on logic and other subjects, and other ancient books from classical Greek, Byzantine Greek, Pahlavi, Neopersian, and Syriac.” These translations were done at the famous Bayt al-Hikma, or House of Wisdom, a library founded in Baghdad early in the Abbasid period.
There were several motivations for this translation movement, including the desire of al-Mansur and his immediate successors to elevate the cultural level of their caliphate by gaining access to Greek science and philosophy. Another reason was to educate the secretaries needed to administer the Abbasid empire. This is evident in the writings of ibn-Qutayb (d. 889), whose Adab al-Katib (Education of the Secretaries) enumerates the subjects that state secretaries should learn, including arithmetic, geometry, and astronomy, as well as practical skills such as surveying, metrology, and civil engineering, for which Greek works in science had to be translated into Arabic to provide the necessary textbooks.
Al-Mahdi commissioned the translation of Aristotle’s Topics into Arabic from Syriac, a form of Aramaic, into which it had been translated from Greek. Later the work was translated directly from Greek into Arabic. Topics taught the art of systematic argumentation, which was vital in discourse between Muslim scholars and those of other faiths and in converting nonbelievers to Islam, which became state policy under the Abbasids. Aristotle’s Physics was first translated into Arabic during the reign of Harun al-Rashid, the motivation apparently being its use in theological disputations concerning cosmology between Muslims and Christians, who at that time had a far better grounding in philosophy.
The program of translation continued until the mid-eleventh century, both in the East and in Muslim Spain. By that time most of the important works of Greek science and philosophy were available in Arabic translations, along with commentaries on these works and the original treatises by Islamic scientists that had been produced in the interim. Thus, through their contact with surrounding cultures, scholars writing in Arabic were in a position to take the lead in science and philosophy, absorbing what they had learned from the Greeks and adding to it to begin an Islamic renaissance, whose fruits were eventually passed on to western Europe.
At the beginning of the second millennium the so-called Clash of Civilizations became a convergence of cultures, as Islamic science, then at its peak, began to nourish the newly emergent science of western Europe, not only passing along what it had acquired from the Greeks but also works that its own scholars had produced. The effect was profound, for when the heritage of Graeco-Islamic learning became available to Latin scholars, the development of western European science began to accelerate.
The first of the great Islamic scientists, al-Khwarizmi (fl. 828), is renowned for his treatise Kitab al-jabr wa’l-muqabalah, known more simply as Algebra, for it was from this work that Europe later learned the branch of mathematics known by that name. In his preface the author writes that the Caliph al-Ma’mun “encouraged me to compose a compendious work on algebra, confining it to the fine and important parts of its calculation, such as people constantly require in cases of inheritance, legacies, partition, law-suits and trade, and in all their dealings with one another, or where surveying, the digging of canals, geometrical computation, and other objects of various sorts and kinds are concerned.”
Another of al-Khwarizmi’s mathematical works survives only in a unique copy of a Latin translation entitled De numero Indorum (Concerning the Hindu Art of Reckoning), the original Arabic version having been lost. This work, probably based on an Arabic translation of works by the Indian mathematician Brahmagupta (fl. 628), describes the Hindu numerals that eventually became the digits used in the modern Western world. The new notation came to be known as that of al-Khwarizmi, corrupted to “algorism” or “algorithm,” which now means a procedure for solving a mathematical problem in a finite number of steps that often involves repetition of an operation.
Al-Khwarizmi is the author of the earliest extant original work of Islamic astronomy, the Zij al-Sindhind (a zij is an astronomical handbook with tables). This is a set of planetary tables using earlier Indian and Greek astronomical elements, including the epicycle theory. He and Fadil ibn al-Nawbaht are credited with building the first Islamic observatory, which they founded in Baghdad in around 828, during the reign of al-Ma’mun. Al-Khwarizmi also wrote the first comprehensive Islamic treatise on geography, in which he revised much of Ptolemy’s work on this subject, drawing new maps.
Euclid’s Elements was first translated into Arabic during the reign of Harun al-Rashid by the mathematician al-Hajjaj ibn Matar (fl. c. 786–833). Al-Hajjaj did an improved and abbreviated version of the Elements for al-Ma’mun, apparently for use as a school textbook.
Islamic astronomy was dominated by Ptolemy, whose works were translated into Arabic and also disseminated in summaries and commentaries. The earliest Arabic translation of the Almagest is by al-Hajjaj ibn Matar in the first half of the ninth century. The most popular compendium of Ptolemaic astronomy was that of al-Farghani (d. after 861), who used the findings of earlier Islamic astronomers to correct the Almagest. Habash al-Hasib (d. c. 870) produced a set of astronomical tables in which he introduced the trigonometric functions of the sine, cosine, and tangent, which do not appear in Ptolemy’s works.
Islamic science developed apace with the translation movement, which involved philosophers as well as scientists. The beginning of Islamic philosophy is credited to Yaqub ibn Ishaq al-Kindi (c. 795–866), the Latin Alkindes, famous in the West as the “Philosopher of the Arabs.” Al-Kindi was from a wealthy Arab family in Kufa, in present-day Iraq, which he left to study in Baghdad. There he worked in the Bayt al-Hikma, enjoying the patronage of al-Ma’mun and his immediate successors.
Al-Kindi, though not a translator himself, benefited from the translation movement to become the first of the Islamic philosopher-scientists, founding the Aristotelian movement in Islam. He was a polymath, his treatises including works in geography, politics, philosophy, cosmology, physics, mathematics, meteorology, music, optics, theology, alchemy, and astrology. He was the first Islamic theorist of music, following in the Pythagorean tradition. His work on optics follows Theon of Alexandria in studying the propagation of light and the formation of shadows, and his theory of the emission and transmission of light is based on that of Euclid. Al-Kindi’s ideas on visual perception, which differed from those of Aristotle, together with his studies of the reflection of light, laid the foundations for what became, in the European renaissance, the laws of perspective. His studies of natural science convinced him of the value of rational thought, and as a result he was the first noted Islamic philosopher to be attacked by fundamentalist Muslim clerics.
Hunayn ibn-Ishaq (808–873), known in Latin as Jannitus, was born in al-Hira in southern Iraq, the son of a Nestorian apothecary. He went to Baghdad to study under the Nestorian physician Yuhannah ibn Masawayh (d. 857), personal physician to al-Ma’mun and his successors. He then moved to Baghdad, where he and his students, who included his son Ishaq ibn-Hunayn and his nephew Hubaysh, made meticulous translations from Greek into both Syriac and Arabic. Their translations included the medical works of Hippocrates and Galen, Euclid’s Elements, and De materia medica of Dioscorides, which became the basis for Islamic pharmacology. Ishaq’s extant translation of Aristotle’s Physics is the last and best version of that work in Arabic. His translations included Ptolemy’s Almagest, while his father, Hunayn, revised the Tetrabiblos. Hunayn also revised an earlier translation of Galen by Yahya ibn al-Bitriq (d. 820); these were synopses that contained Plato’s Republic, Timaeus, and Laws, the first rendering of the Platonic dialogues into Arabic.
Hunayn was an outstanding physician and wrote two books on medicine, both extant in Arabic, one of them a history of the subject, the other a treatise entitled On the Properties of Nutrition, based on Galen and other Greek writers. His other writings include treatises on philosophy, astronomy, mathematics, optics, ophthalmology, meteorology, alchemy, and magic, and he is also credited with establishing the technical vocabulary of Islamic science.
Thabit ibn-Qurra (c. 836–901) was born in the Mesopotamian town of Harran, a center of the ancient Sabean cult, an astral religion in which the sun, moon, and five planets were worshipped as divinities. Harran had preserved Hellenic literary culture, and so educated Sabeans like Thabit were fluent in Greek as well as in Syriac and Arabic.
Thabit translated works from both Syriac and Greek into Arabic, his works including improved editions of Euclid’s Elements and Ptolemy’s Almagest. His descendants produced Arabic translations of the writings of Archimedes and Apollonius of Perge, among other works. Thabit’s own treatises include works on physics, astronomy, astrology, dynamics, mechanics, optics, and mathematics. He wrote a commentary on Aristotle’s Physics and an original work entitled The Nature and Influence of the Stars, which laid out the ideological foundations of Islamic astrology. He also wrote a comprehensive work on the construction and theory of sundials.
Another prominent figure of the translation movement was Qusta ibn Luqa, a Greek-speaking Christian from Lebanon, who worked in Baghdad as a physician, scientist, and translator until his death in 913. His translations included works of Aristarchus, Hero, and Diophantus. He wrote commentaries on Euclid’s Elements and De Materia medica of Diophantus, as well as original treatises on medicine, astronomy, metrology, and optics. His medical works include a treatise on sexual hygiene and a book on medicine for pilgrims.
Astronomy always held pride of place among the sciences in Islam, and Arabic astronomers often waxed eloquent in extolling the utility and godliness of their field. Muhammed ibn Jabir al-Battani (858–929) begins his Zij al-Sabi by citing a verse of the Kuran in praise of astronomy. “He it is who appointed the sun a splendor and the moon a light, and measured for her stages, that ye might know the number of the years, and the reckoning.”
Al-Battani, the Latin Albategnius, was a Sabean from Harran who had a private observatory in the Syrian town of al-Raqqa. His Zij al Sabi, known in its Latin translation as De scientia stellarum (On the Science of Stars), was used in Europe down to the end of the eighteenth century. In the preface to his Zij, al-Battani writes that the errors he found in earlier astronomical treatises had led him to improve the Ptolemaic model with new theories and observations, just as Ptolemy had done with the work of Hipparchus and other predecessors. Ptolemy had measured the rate of precession to be 1° in one hundred years, while al-Battani found it to be 1° in sixty-six years, whereas the correct value is 1° in seventy-two years. Al-Battani’s astronomical writings were translated into Latin and were used by astronomers up to the seventeenth century.
Many Arabic astronomers doubled as astrologers, as did some in western Europe, most notably Kepler. The first Arabic philosopher to attack astrology was Abu Nasr al-Farabi (c. 870–950), known in the West as Alfarabius, whose scientific works include commentaries on Euclid’s Elements and Ptolemy’s Almagest.
Astrology was also attacked by Sa’di of Shiraz, the famous thirteenth-century Persian poet. One of his tales tells of an astrologer who returned home unexpectedly and found his wife in bed with a stranger. When he raised a fuss about this, a stranger mocked him by saying, “What can you know of the celestial sphere when you cannot tell who is in your own house.”
The first great writer in Islamic medicine is Abu Bakr Muhammed ibn Zakariya al-Razi (c. 865–c. 930), the Latin Rhazes, who was born in the Persian city of Rai. He was famous as a physician in both the East and the West, where he was known as the Arabic Galen. He studied in Rai and became the director of the hospital there. He later headed the hospital in Baghdad, where students came from afar to study with him. He is credited with 232 works, of which most are lost, including all of his philosophical treatises. The most important of his surviving medical works is al-Hawi, known in its Latin translation as Continens, the longest extant Arabic work on medicine. His treatise on smallpox and measles, known in Latin as De peste, was translated into English and other Western languages and published in forty editions between the fifteenth century and the nineteenth.
Ibn Sina (980–1037) was born and educated near Bukhara (in present-day Uzbekistan), and later he lived in the Persian towns of Rai and Hamadan, where he died. He is credited with some 270 works; the best known are the Canon of Medicine and the Book of Healing, which also contain chapters on logic, ethics, mathematics, physics, optics, chemistry, biology, botany, geology, mineralogy, meteorology, and seismology. He also wrote on the classification of the sciences, ranking philosophy as “queen of the sciences.” His medical writings, along with those of al-Razi, were translated into Latin and used as basic texts in Europe’s medical schools until the seventeenth century. His Canon of Medicine was far ahead of its times in dealing with such matters as cancer treatment, the influence of the environment, the beneficial effects of physical exercise, and the need for psychotherapy, where he recognized the connection between emotional and physical states, including the heartache of unrequited love.
Ibn Sina was the first Muslim scientist to revive the impetus theory of John Philoponus, an attempt to explain why a projectile continues to move after it is fired. He described this impetus as a “borrowed power” given to the projectile by the source of motion, “just as heat is given to water by a fire.”
Ibn Sina had immense influence on the subsequent development of science, both in the Islamic world and in Latin Europe, where, as Avicenna, he was known as the Prince of Physicians. His ideas, which combined Platonic and Aristotelian concepts, had a profound effect on Western thought in the thirteenth century, when the new European science was being created from Graeco-Arabic sources.
When I am asked about whether Islamic science produced any original works that surpassed those of the ancient Greeks, I point out in particular Abu `Ali al-Hasan ibn al-Haytham (c. 965–c. 1041), known in the West as Alhazen. Ibn al-Haytham was born in Basra, in Iraq, where he studied mathematics and science before going to Egypt during the reign of the Fatimid Caliph al-Hakim. He took up residence near the al-Azhar mosque, teaching and copying Euclid’s Elements and Ptolemy’s Almagest, which supported him while he worked on his researches.
Ibn al-Haytham’s masterpiece is his Book of Optics, which is considered to be one of the most important and influential works ever produced in Islamic science, representing a definite advance beyond what had been achieved by the ancient Greeks in their study of light. The Optics was translated into Latin in the late twelfth or early thirteenth century, under the title Perspectiva. The Perspectiva was the subject of studies and commentaries in Europe up until the seventeenth century, stimulating the study of optics in the Latin West.
The seventh and final book of the Optics is devoted to dioptrics, phenomena involving refraction, which also had been studied by Ptolemy. Ibn al-Haytham gives a detailed description of his improved version of Ptolemy’s instrument for measuring refraction, which he used to study the bending of light at plane and spherical surfaces with air-water, air-glass, and water-glass interfaces. Ibn al-Haytham’s theory introduced a new method, that of resolving the velocity of light into two independent components, one along the normal and the other perpendicular to it, where the first component changed in the refraction while the second remained constant. This approach, called the parallelogram method, was used by a number of European physicists from the thirteenth century onward, in the study of both light and motion. One of his works describes the camera obscura, or pinhole camera, the first appearance of the device that eventually led to the development of photography.
Gerbert of Aurillac appears to have been the first Western scholar to write about the all-important astrolabe, the basic astronomical instrument and calculator that Islamic astronomers had inherited from the Greeks, probably invented by Hipparchus.
The first European to follow Gerbert’s lead was the German monk Hermann the Lame (1013–1054), who wrote about the astrolabe as well as the chilinder and quadrant, two other astronomical instruments that had been widely used in the Islamic world. The chilinder is a portable sundial designed to give the time for a single latitude, while the quadrant is used to measure the sun’s altitude and also give the latitude and time of day. These instruments are described in De mensure astrolabi and De utilitatibus astrolabi, two works that have been attributed to Hermann, though the first part of the latter work may be by Gerbert d’Aurillac. All three instruments were widely used in the Latin West after they were acquired from Islamic sources.
The first astronomer in western Europe known to have used the astrolabe is Walcher of Malvern, a German monk who had come to England in about 1091. While traveling in Italy Walcher had observed the eclipse of October 30, 1091, and after his return to England he noted that the time of day was considerably different from that recorded by a brother monk at Malvern. At Malvern the following year he observed the eclipse of October 18, using his astrolabe to locate it accurately on the celestial sphere, where in recording its position he uses the Arabic names for three stars as if they were well known to his readers. Using his early observations, Walcher compiled a set of tables giving the time of new moons from 1036 through 1111, which he thought to be important for use in astrology. The celestial coordinates in these tables were worked out by the clumsy methods of Roman fractions, but in a later treatise, written in 1120, he used the system of degrees, minutes, and seconds of arc that Arab astronomers had inherited from the Greeks. Walcher seems to have taken this system from a treatise published in 1115 by Petrus Alphonsus, a Spanish Jew.
The first of the important translators of Graeco-Islamic science from Arabic into Latin is Constantine the African (fl. 1065–1085). Constantine was a Muslim merchant from Carthage in North Africa who visited the Lombard court in Salerno in southern Italy, where he learned that there was no medical literature available in Latin. He went back to North Africa and studied medicine for three years, after which he returned to Salerno with a collection of medical writings in Arabic, perhaps as early as 1065. A few years later he converted to Christianity and became a monk in the Benedictine abbey at Monte Cassino. There, under the patronage of the famous abbot Desiderius, later Pope Victor III, he spent the rest of his days in making Latin translations or compilations from Arabic medical texts. Constantine is credited with a score of translations, including works of Hippocrates and Galen and the Arabic writer Haly Abbas (c. 925–994), whose Kitab al-Maliki he translated as the Pentegne, divided into two sections, theorica and practica.
Constantine’s translations were used at the medical school of Salerno, the first in Europe, founded in the mid-eleventh century. These works were introduced into the curriculum under the title of Ars medicine or Articella, which formed the foundation of a large part of European medical education on into the sixteenth century. Constantine had always emphasized that medicine should be taught as a basic part of natural philosophy, and the theorica section of the Pantegne provided the basis for this integrated study.
The First Crusade, which began in 1096, led to the establishment of Crusader states in Edessa, Antioch, and Jerusalem, an important factor in opening up Islamic culture to western Europe. One of the earliest examples of this cross-cultural contact is the work of Stephen of Antioch, a translator who flourished in the first half of the twelfth century. According to Matthew of Ferrara, Stephen was a Pisan who went to Syria, probably to the Pisan quarter of Antioch, where his uncle was the Roman Catholic Patriarch.
At Antioch, Stephen learned Arabic and translated the Kitab al-Maliki of Haly Abbas into Latin, under the title of Regalis dispositio, which he completed in 1127. Stephen says that he did so because he felt that the previous translation of this work by Constantine the African was incomplete and distorted. He also added a prologue to the second part of this work, a list of synonyms in three columns—Arabic, Latin, and Greek—as an aid to help his readers understand the Arabic terms in De materia medica of Dioscorides. There he noted that those who have difficulty with the Latin terms can consult experts, “for in Sicily and Salerno, where students of such matters are chiefly to be found, there are both Greeks and men familiar with Arabic.”
The leading figure in the early European acquisition of Arabic science was Adelard of Bath (fl. 1116–1142). In the introduction to his Questiones naturales, addressed to his nephew, Adelard wrote of his “long period of study abroad,” first in France, where he studied at Tours and taught in Laon. He then went on to Salerno, Sicily, Tarsus, Antioch, and probably also to Spain, spending a total of seven years abroad.
Adelard may have learned Arabic in Spain, for his translation of the Astronomical Tables of al-Khwarizmi was from the revised version of the Andalusian astronomer Maslama al-Majriti (d. 1071). The Tables, comprising thirty-seven introductory chapters and 116 listings of celestial data, provided Christian Europe with its first knowledge of Graeco-Arabic-Indian astronomy and mathematics, including the first tables of the trigonometric sine function to appear in Latin.
Adelard may also have been the author of the first Latin translation of another work by al-Khwarizmi, De numero Indorum (Concerning the Hindu Art of Reckoning), which describes the Hindu-Arabic numerals that eventually became the digits used in the modern Western world. These numerals, including the all-important zero, may have been introduced in India from Greek sources in Alexandria and were further developed in the Arab world before taking their present form in late medieval Europe. They replaced the unwieldy Roman numerals and were a great stimulus to the development of mathematics in western Europe.
Adelard was probably also the first to give a full Latin translation of Euclid’s Elements, which he did in three versions. The second of these became very popular, beginning the process that led to Euclid’s domination of medieval European mathematics. The first complete English edition appears in Robert Recorde’s The Pathway to Knowledge, in London in 1551. Recorde realized that Euclid’s axioms would be far beyond the mathematical ability of the “simple ignorant” people who would read his book, “for nother is there anie matter more straunge in the English tunge, than this whereof never booke was written before now, in that tunge before now, in that tunge.” The first proper English translation, published in London in 1570, was by Sir Henry Billingsley, later lord mayor of London, with a “fruitfull Praeface” by John Dee, who wrote that the book contains “manifolde additions, Scholies, Annotations and Inventions … gathered out of the most famous and chiefe Mathematicians, both of old time and in our age.”
Adelard says that his Questiones naturalis was written to explain “something new from my Arab studies.” The Questiones are seventy-six in number, 1–6 dealing with plants, 7–14 with birds, 15–16 with mankind in general, 17–32 with psychology, 33–47 with the human body, and 48–76 with meteorology and astronomy. Throughout he looks for natural rather than supernatural causes of phenomena, a practice that would be followed by later European writers.
In one particularly interesting passage in this work, Adelard’s nephew asks him if it were not “better to attribute all the operations of the universe to God.” Adelard replied: “I do not detract from God. Everything that is, is from him and because of him. But [nature] is not confused and without system and so far as human knowledge has progressed it should be given a hearing. Only when it fails utterly should there be a recourse to God.”
The Questiones naturalis remained popular throughout the rest of the Middle Ages, with three editions appearing before 1500, as well as a Hebrew version. Adelard also wrote works ranging from trigonometry to astrology and from Platonic philosophy to falconry. His last work was a treatise on the astrolabe, in which once more he explained “the opinions of the Arabs,” this time concerning astronomy. The treatise describes the workings of the astrolabe and its various applications in celestial measurements, using Arabic terms freely and quoting from Adelard’s other works, particularly his translations of Euclid’s Elements and the planetary tables of al-Khwarizmi.
A woman personifying Geometry, and her students, from a manuscript of the Elements of Euclid translated from the Arabic by Adelard of Bath
Toledo became a center for translation from the Arabic after its recapture from the Moors in 1085 by Alfonso VI, king of Castile and Leon, the first major triumph of the reconquista, the Christian reconquest of Andalusia.
The Muslim conquest of the Iberian peninsula began in the spring of 711, when Musa ibn Nusayr, the Arab governor of the Maghreb, or northwest Africa, sent an army across the Strait of Gibraltar under the command of Tariq ibn Ziyad. At that time the Iberian peninsula was ruled by the Visigoths, whose king, Roderic, was defeated and killed in July 711 by Tariq, who went on to capture Cordoba and Toledo, the Visigoth capital.
Musa followed across the strait with an even larger army and, after taking Seville and other cities and fortresses, he joined Tariq in Toledo. Musa was then recalled to Damascus by the Umayyad caliph, leaving the conquered lands in the hands of his son `Abd al-Aziz, who, in the three years of his governorship (712–715), extended his control over most of the Iberian peninsula, which came to be known to the Arabs as al-Andalus.
The first Abbasid caliph, Abu al-Abbas al-Saffah (r. 749–754), sought to consolidate his power by slaughtering all of the members of the Umayyad family, but one of them, the young prince `Abd al-Rahman, escaped to the Maghreb and then to Spain, where in 756 he established himself in Cordoba, taking the title of amir. This was the beginning of the Umayyad dynasty in Spain, which was to rule al-Andalus until 1031. `Abd al-Rahman I (r. 756–788) established Cordoba as his capital, and in the years 784–786 he erected the Great Mosque, which was rebuilt and enlarged by several of his successors. `Abd al-Rahman II (r. 822–852) began the development of science in al-Andalus by sending an agent to the East to buy books, which an anonymous Maghreb chronicler says included astronomical tables as well as works in astronomy, philosophy, medicine, and music.
The Umayyad dynasty in al-Andalus reached its peak under `Abd al-Rahman III (r. 912–961), who in 929 took the title of caliph, emphasizing the independence of al-Andalus from the Abbasid caliphate in the East. This began the golden age of Muslim Cordoba, known to Arab chroniclers as the “the bride of al-Andalus.” The golden age continued under `Abd al-Rahman’s son and successor, al-Hakem II (r. 961–976), and his grandson Hisham II (976–1009), who was a puppet in the hands of his vizier al-Mansur.
Al-Hakem built one of the greatest libraries in the Islamic world in Cordoba, rivaling those at Baghdad and Cairo. The caliph’s library, together with the twenty-seven free schools he founded in his capital, gave Cordoba a reputation for learning that spread throughout Europe, attracting Christian scholars as well as Muslims, not to mention the Sephardic Jews who lived under Islamic rule.
The culmination of Arabic philosophy comes with ibn Rushd, the Latin Averroës (1126–1198), who was from a distinguished family of Cordoban jurists.
He studied theology, law, medicine, and philosophy, including the works of Aristotle, particularly his writings in physics and natural science.
The philosophical writings of ibn Rushd can be divided into two groups, his commentaries on Aristotle and his own treatises on philosophy. He regarded the philosophy of Aristotle as the last word, to the extent that truth can be understood by the human mind. By the beginning of the thirteenth century ibn Rushd was considered to be the outstanding interpreter of Aristotle and his works were translated into Hebrew. By the end of that century nearly half of his commentaries on Aristotle had been translated from Arabic into Latin, so that he came to be known in the West as the Commentator.
Ibn Rushd interpreted the concept of creation in such a way as to deny free will not only to man but even to God himself. According to ibn Rushd, the world had been created by a hierarchy of necessary causes starting with God and descending through the various Intelligences that moved the celestial spheres. He accepted Aristotle’s planetary model of the homocentric spheres and rejected Ptolemy’s theory of eccentrics and epicycles. He writes of his astronomical researches in his commentary on Aristotle’s Metaphysics, where he expresses his belief that the prevailing Ptolemaic theory is a mathematical fiction that has no basis in reality.
One of the discoveries made by ibn Rushd in his medical researches was that the retina rather than the lens is the sensitive element in the eye, an idea that was forgotten until it was revived by the anatomist Felix Plater (1536–1614).
After al-Mansur’s death in 1002, the caliphate passed in turn to several claimants in the principal cities of al-Andalus, and finally it was abolished altogether in 1031. The fall of the caliphate was followed by a period of sixty years in which al-Andalus was fragmented into a mosaic of petty Muslim states, allowing the Christian kingdoms of northern Spain to start expanding south. The last remnant of Muslim Spain was the Banu Nasr kingdom of Granada, which hung on until its capture in 1492 by Ferdinand II of Aragon and Isabella of Castile, the Catholic kings, who that year drove the last of the Moors from Spain, also expelling the Jews.
The initiative for the translation movement in Spain seems to have come from Raymond, archbishop of Toledo, (r. 1125–51) as evidenced in the dedications of a contemporary Toledan translator, Domenicus Gundissalinus (c. 1110–c. 1190).
Gundissalinus, archbishop of Segovia, did several translations and adaptations of Arabic philosophy, including works by Al-Kindi, ibn Rushd, and ibn Sina, as well as one by the Jewish physician Isaac Judaeus. The translations attributed to Gundissalinus were probably done by him in collaboration with others who were fluent in Arabic, though only in one work, the De anima of ibn Sina, is his name linked with that of a coauthor.
Gundissalinus also wrote five philosophical works on his own, based largely on the books that he had translated as well as on Latin sources. His De divisione philosophiae, which incorporates the systems of both Aristotle and Arabic philosophers, is a classification of the sciences transcending the traditional division of studies in the trivium and quadrivium, and it influenced later schemes of classification in western Europe.
Sephardic Jews played an important role in the translation movement, since their languages included Arabic and Latin as well as Hebrew, and several of them wrote original works of enduring importance. The most influential was the mathematician, astronomer, and philosopher Abraham bar Hiyya Ha-Nasi, known in Latin as Savasorda, who was born in Barcelona in 1070 and died in Provence in 1136 or 1145.
Savasorda’s most important work is his Hebrew thesis on practical arithmetic, which he and Plato of Tivoli translated into Latin in 1145 as the Liber embadorum. This was one of the earliest works on Arabic algebra and trigonometry to be published in Latin Europe, and it contains the first solution of the standard quadratic equation to appear in the West. It was also the earliest to deal with Euclid’s Division of Figures, which has not survived in Greek and only partially in Arabic. Savasorda’s Encyclopedia is a compendium of practical reckoning and business arithmetic as well as the theory of numbers and geometric definition. It has been defined as “probably the earliest algorithmic work written in western Europe.”
Among the other figures in the translation of Graeco-Arabic science to Latin, the most prolific by far was Gerard of Cremona (1114–1187), whose influence was evident for centuries. The few details that are known of Gerard’s life come mostly from a short biography and eulogy written in Cremona after his death. It notes that Gerard completed his education in the schools of the Latins before going to Toledo, which he would have reached by 1144 at the latest, when he would have been thirty years old. The biography goes on to say that it was his love of Ptolemy’s Almagest, which he knew was not available in Latin, that drew Gerard to Toledo, and “there, seeing the abundance of books in Arabic on every subject … he learned the Arabic language, in order to be able to translate.”
Gerard’s translations include Arabic versions of writings by Aristotle, Euclid, Archimedes, Ptolemy, and Galen, as well as works by Thabit ibn-Qurra, al-Kindi, al-Khwarizmi, al-Razi, ibn Sina, and ibn al-Haytham. The subjects covered in these translations include twenty-one works on medicine; seventeen on geometry, mathematics, optics, weights, and dynamics; fourteen on philosophy and logic; twelve on astronomy and astrology; and seven on alchemy, divination, and geomancy, or predicting the future from geographic features.
More of Arabic science passed to the West through Gerard than from any other source. His translations produced a great impact upon the development of European science, particularly in medicine, where students in the Latin West took advantage of the more advanced state of medical studies in medieval Islam, particularly those of ibn Sina. Ibn Sina’s Canon of Medicine, particularly its encyclopedic detail on the practical side of the healing art, remained unsurpassed up until the beginning of the twentieth century, at least according to the opinion of pharmaco-epidemiology professor John Urquhart. Writing in the British Medical Journal in 2006, Urquhart said: “If the year were 1900 and you were marooned and in need of a guide for practical medicine, which book would you want by your side? My choice was Ibn Sina.”
Gerard’s translations in astronomy, physics, and mathematics were also very influential, particularly those of Archimedes and Euclid, since they represented a scientific approach to the study of nature rather than the philosophical and theological attitude that had been prevalent in the Latin West. Gerard’s translation of Ptolemy’s Almagest was particularly important; as historian Charles Homer Haskins noted, through this work “the fullness of Greek astronomy reached western Europe.”
The English scholar Robert of Chester, a younger contemporary of Adelard, collaborated with other translators at several places in southern France and Spain, including Toledo. Robert’s solo translations include al-Khwarizmi’s Algebra (dated Segovia, 1145); a treatise on the astrolabe (London, 1147); a set of astronomical tables for the longitude of London (1149–1150); and a revision, also for the meridian of London, of Adelard’s version of the tables of al-Khwarizmi. His treatises on astrolabes and astronomical tables indicate that work on both observational and theoretical astronomy was being done in England at the time.
One of the extant manuscripts of Robert’s revisions of al-Khwarizmi’s work contains astronomical tables for the longitude of Hereford in England, dated 1178, which have been attributed to Roger of Hereford, who wrote several works on astronomy and astrology in the decade 1170–1180. One of these, a survey entitled Liber de divisione astronomiae, begins with the phrase “In the name of God the pious and merciful,” the traditional opening of an Islamic treatise, suggesting that this is a translation from the Arabic, though the author is unknown. But interest in the astrolabe and in astronomical tables revised for Hereford indicates that Roger was actively engaged in astronomy himself, the earliest-known astronomer in Latin Europe.
Alfred of Sareshel, another twelfth-century English scholar, dedicated one of his translations to Roger of Hereford. Alfred did translations of several Aristotelian works from Arabic, together with commentaries, and he also translated parts of ibn Rushd’s Kitab al-Shifa, the sections on geology and alchemy, which he entitled De mineralibus. Alfred seems to have learned Arabic in Spain, where he probably did his translation of ibn Rushd, and he also appears to have used Greek sources, particularly in his works on Aristotle, whose natural philosophy and metaphysics he introduced to England.
The most important interface among Greek, Latin, and Arabic culture in the twelfth century was the Norman realm in southern Italy and Sicily, the kingdom of the Two Sicilies. When Count Roger I conquered Palermo in 1091, it had been under Muslim domination for nearly two centuries. He reduced the Muslims to the status of serfs except in Palermo, his capital, where he employed the most talented of them as civil servants, so that Greek, Latin, and Arabic were spoken in the Norman court and used in royal charters and registers. Under his son Roger II (r. 1130–1154), Palermo became a center of culture for both Christians and Muslims, surpassed only by Cordoba and Toledo. Beginning under Roger II, and continuing with his successors, the Sicilian court sponsored numerous translations from both Greek and Arabic into Latin.
Roger II was particularly interested in geography, but he was dissatisfied with existing Greek and Arabic geographical works. Thus in 1138 he wrote to al-Idrisi (1100–1166), the distinguished Muslim geographer and cartographer, who was then living in Cueta, and invited him to visit Palermo, saying, “If you live among the Muslims, their kings will contrive to kill you, but if you stay with me you will be safe.” Al-Idrisi accepted the offer and lived in Palermo until Roger’s death in 1154, after which he returned to Cueta and passed his remaining days there.
Roger commissioned al-Idrisi to create a large circular relief map of the world in silver, the data for which came from Greek and Arabic sources, principally Ptolemy’s Geography, as well as travelers and the king’s envoys. The map has long since vanished, but its features were probably reproduced in the sectional maps in al-Idrisi’s Arabic geographical compendium, Kitab nuzhat al-mushtaq fi ikhtiraq al-afar, which has survived. The compendium deals with both physical and descriptive geography, with information on political, economic, and social conditions in the lands around the Mediterranean and in the Middle East, and is thus a veritable encyclopedia of the medieval world. Al-Idrisi’s work was a popular textbook in Europe for several centuries and a number of abridgements were done, the first at Rome in 1592. A Latin translation was published at Paris in 1619, and a two-volume French translation was done in 1830–1840, entitled Géographie d’Edrisi.
Frederick II of Hohenstauffen (r. 1211–1250), the Holy Roman Emperor and king of the Two Sicilies, was a grandson of the Emperor Frederick I Barbarossa and the Norman king Roger II. Known in his time as stupor mundi, “the wonder of the world,” he had been raised from age seven to twelve in Palermo, where he grew up speaking Arabic and Sicilian as well as learning Latin and Greek. When he became emperor in 1211, at the age of fourteen, he turned away from his northern dominions to his kingdom of the Two Sicilies, where, like his Norman predecessors, who were known as “baptized sultans,” he indulged himself in his harem in the style of an oriental potentate.
Frederick was deeply interested in science and mathematics, and he invited a number of scholars to his brilliant court, most notably John of Palermo, Master Theodorus, and Michael Scot, calling them his “philosophers.” He subsidized their scientific writings and translations, which included works of Aristotle on physics and logic, some of which he presented in 1232 to the faculty at Bologna University. The letter that Frederick sent with the gift told of how he had loved learning since his youth, and of how he still took time from affairs of state to read in his library, where numerous manuscripts of all kinds “classified in order, enrich our cupboards.”
Frederick’s scholarship is evident in his famous book on falconry, De arte venandi cum avibus, or The Art of Hunting with Birds. This is a scientific work on ornithology as well as a detailed and beautifully illustrated manual of falconry as an art rather than a sport. Frederick acknowledged his debt to Aristotle’s Zoology, which had been translated by Michael Scot earlier in the twelfth century. But he was critical of some aspects of the work, as he wrote in the preface to his manual: “We have followed Aristotle when it was opportune, but in many cases, especially in that which regards the nature of some birds, he appears to have departed from the truth. That is why we have not always followed the prince of philosophers, because rarely, or never, had he the experience of falconing which we have loved and practiced always.” This is the earliest European work critical of Aristotle, a view that is one of Galileo’s main claims to fame.
One of those with whom Frederick corresponded was the renowned mathematician Leonardo Fibonacci (c. 1170–after 1240), who had been presented to him when he held court at Pisa around 1225. Fibonacci had at that time just completed his treatise on squared numbers, the Liber quadratorum, which he dedicated to Frederick, noting, “I have heard from the Podesta of Pisa that it pleases you from time to time to hear subtle reasoning in Geometry and Arithmetic.”
Fibonacci was born in Pisa around 1170. He wrote about his life in the preface to his most famous work, the book on calculations entitled Liber abbaci. His father, a secretary of the Republic of Pisa, was around 1192 appointed director of the Pisan trading colony in the Algerian city of Bugia (now Bouge). He was brought to Bugia by his father to be trained in the art of calculating, which he learned to do “with the new Indian numerals,” the so-called Hindu-Arabic numbers, which he would introduce to Europe in his Liber abbaci. His father also sent him on business trips to Provence, Sicily, Egypt, Syria, and Constantinople, where he met with Latin, Greek, and Arabic mathematicians. Around 1200 he returned to Pisa, where he spent the rest of his days writing the mathematical treatises that made him the greatest mathematician of the Middle Ages.
His extant works are the Liber abbaci, first published in 1202 and revised in 1228; the Practica geometriae (1220/1221), on applied geometry; a treatise entitled Flos (1225), sent to Frederick II in response to mathematical questions that had been put to Fibonacci by John of Palermo at the time of the emperor’s visit to Pisa; an undated letter to Master Theodorus, one of the court “philosophers”; and the Liber quadratorum (1225). The latter work contains the famous “rabbit problem”: “How many pairs of rabbits will be produced in a year, beginning with a single pair, if in every month each pair produces a new pair which become productive from the second month on?” The solution to this problem gave rise to the so-called Fibonacci numbers, a progression in which each number is the sum of the two that precede it:
1, 1, 2, 3, 5, 8, 13, 21 …
The sequence is a mathematical wonder that continues to fascinate mathematicians. Fibonacci’s sources, where they can be traced, include Greek, Roman, Indian, and Arabic works, which he synthesized and, adding to them with his own creative genius, stimulated the beginning of the new European mathematics.
Master Theodorus, who is usually referred to as the Philosopher, was born in Antioch. He served Frederick as secretary, ambassador, astrologer, and translator, from both Greek and Arabic into Latin, and he was also the emperor’s chief confectioner. One of his works is a translation of an Arabic work on falconry. He served the emperor until the time of his death around 1250, when Frederick regranted the estate that “the late Theodore our philosopher held so long as he lived.”
Theodorus had probably succeeded Michael Scot as court astrologer. Michael was born in the last years of the twelfth century, probably in Scotland. Nothing is known of his university studies, but his references to Paris indicate that he may have studied and lectured there as well as in Bologna, where he did some medical research in 1220–1221. He may have learned Arabic and some Hebrew in Toledo where, around 1217, he translated al-Bitruji’s On the Sphere, with the help of Abuteus Levita, a Jew who later converted to Christianity. By 1220 he had completed what became the standard Latin versions of Aristotle’s Physica, De caelo, and De anima with Averroës’s commentaries. He had become a priest by 1224, when Pope Honorius II appointed him as archbishop of Cashel, in Ireland, and obtained benefices for him in England. He declined the appointment as archbishop, saying that he did not speak Irish, and was then given further benefices in England and Scotland by the archbishop of Canterbury.
When Fibonacci completed his revised version of Liber abbaci in 1228, he sent it to Michael, who by that time seems to have entered the service of Frederick II as court astrologer and translator. Aside from his translations, Michael’s major work was a comprehensive introduction to the sciences, including alchemy, on which, according to historian Lynn Thorndike, he may also have written a separate thesis. Thorndike quoted Michael in describing his procedure for transmuting copper into gold:
“Take the blood of a ruddy man and the blood of a red owl, burning saffron, Roman vitriol, resin well pounded, natural alum, Roman alum, sugared alum, alum of Castile, red tartar, marcasite, golden alum of Tunis, which is red, and salt.” These ingredients are to be pounded in a mortar, passed through sieves, treated with the urine of an animal called taxo, or with the juice of wild cucumber, then dried, brayed again, and then put into a crucible with the copper.
Michael also wrote a voluminous treatise known in English as Introduction to Astrology, a subject that he thought should be studied by all physicians. The treatise covers every aspect of astrology and divination including necromancy, or conjuring up the spirits of the dead to reveal the future or influence the course of coming events, as well as nigromancy, or black magic, dealing with spells cast at night rather than in daylight.
Frederick addressed a long series of extraordinary questions to Michael, who inserted the questionnaire as an addendum to a work entitled Libers particularis. Frederick’s interest in necromancy is indicated in one of the questions that he asked Michael: “And how is it that the soul of a living man which has passed away to another life than ours cannot be induced to return by first love or even by hate, just as it had been nothing, nor does it seem to care at all for what it has left behind whether it be saved or lost.” Michael boasted that he could answer all of the questions asked by the emperor, including his query as to “whether one soul in the next world knows another and whether one can return to this life to speak and show one’s self; and how many are the pains of hell.”
All of this led to Michael’s posthumous fame as a magician, clouding his reputation as a scientist and translator, which is in any event controversial. Roger Bacon referred to Michael as “a notable inquirer into matter, motion, and the course of the constellations,” but at the same time he listed him among those translators who “understood neither sciences nor languages, not even Latin,” and said that his translations were for the most part done by a Jew named Andrew. Bacon credits Michael with having introduced the natural philosophy of Aristotle to the Latin West, though Michael actually transmitted only three Aristotelian works.
Along with Gerbert d’Aurillac, Michael was said to have sold his soul to the devil in exchange for his knowledge of the black arts and the magic of science. Dante writes of him in canto 20 of the Inferno, where he is pointed out in the fourth ditch of the eighth circle of Hell, among the other diviners: “That other, round the loins / So slender of his shape, was Michael Scot / Practised in every slight of magic wile.”
European science had by now outgrown the confines of the monasteries where it first developed, spreading into the outer world and interacting with Byzantine and Islamic culture, going beyond the philosophic and mathematical science of the works in the great Library of Alexandria to explore new worlds. What is more, scholarship was no longer restricted to the confines of a monastery, for the level of knowledge in the Latin West was now such that men like Gerard of Cremona and Adelard of Bath now sought out and found new sources of Greco-Islamic science, most notably ibn al-Haytham, whose work on the science of light went well beyond any work of optics produced in the Greek world. And the first step in creating institutions of higher learning had been taken in the foundation of the medical school in Salerno, with its curriculum based on both Greek and Islamic medicine.
These advances had been largely due to the political stability in western Europe at the beginning of the second Christian millennium, which fostered the growth of commerce and increased prosperity. Technological advances such as the improvement and wider use of the waterwheel and the rotation of crops created a much greater agricultural output. This led to a population explosion, and it is estimated that between the years 1000 and 1200 the population of western Europe may have increased by as much as a factor of four. There was an even greater increase in the urban population, which led to more economic opportunity, stimulating intellectual interchange, and the creation of schools, including the first universities of western Europe. The Dark Ages were definitely over; modern Europe was emerging, and with it European science.
Michael Scot is believed to have died in 1236 in Germany, where he had accompanied the emperor Frederick. By that time almost all of Graeco-Islamic science that would be translated from Arabic into Latin was available in western Europe, setting the stage for the next phase of the program, translating works directly from Greek into Latin.