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; their king, Roderick, 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 (712-15), extended his control over most of the Iberian Peninsula, which came to known to the Arabs as Al-Andalus.
The first Abbasid caliph, Abu'l-Abbas al-Saffah (r. 749-54), 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, or emir. This was the beginning of the Umayyad dynasty in Spain, which was to rule Al-Andalus until 1031. Abd al-Rahman I (r. 756-88) established Cordoba as his capital, and in the years 784-86 he erected the Great Mosque, which was rebuilt and enlarged by several of his successors.
The Umayyad dynasty in Al-Andalus reached its peak under ‘Abd al-Rahman III (r. 912-61), 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,” referred to by the Saxon nun Hroswith as “the ornament of the world.” The golden age continued under Abd al-Rahman's son and successor, al-Hakem II (r. 961-76), and his grandson Hisham II (976-1009), who was a puppet in the hands of his vizier al-Mansur, the Latin Almanzor.
Abd al-Raman chose a site outside Cordoba to build the magnificent palace of Madinat al-Zahra, “the radiant.” 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 Jews who lived under Islamic rule. As the Maghreb historian al-Maqqari was to write of tenth-century Cordoba: “In four things Cordoba surpasses the capitals of the world. Among them are the bridge over the river and the mosque. These are the first two; the third is Madinat al-Zahra; but the greatest of all things is knowledge—and that is the fourth.”
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, beginning what came to be known as the Reconquista. The first major Christian triumph came in 1085, when Toledo fell to the king of Castile and León, Alfonso VI (r. 1072-1109).
The fall of Toledo led the petty Muslim rulers to seek help from the powerful ruler of the Almoravids in Morocco, Yusuf ibn Tashfin (r. 1061-1106). Yusuf crossed into Al-Andalus in 1086 and decisively defeated Alfonso's army, saving southern Spain from falling into Christian hands. This led to the domination of Al-Andalus by the Almoravids, which lasted until the mid-twelfth century, when they were supplanted by another powerful dynasty from the Maghreb, the Almohads. During the reign of Abd al-Mu'min (r. 1130-63) the Almohads extended their power throughout both the Maghreb and Al-Andalus. The Almohads suffered a crushing defeat in 1212 at the hands of a Christian coalition, which in the next half century seized the major Muslim cities in Al-Andalus, taking Cordoba in 1236. Virtually all that remained 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 drove the last of the Moors from Spain.
Abd al-Rahman II (r. 822-52) 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 amir was keenly interested in astronomy and astrology, perhaps stimulated by a total eclipse of the sun on 17 September 833, which so terrified the people of Cordoba that they quickly gathered at the Great Mosque to pray for divine deliverance.
The amir‘s court poet and astrologer was Abbas ibn Firnas (d. 887), who introduced a version of al-Khwarizmi's astronomical tables, the Zij al-Sindhind With the amir‘s patronage, Ibn Firnas built an observatory in Cordoba, with a planetarium, an armillary sphere, and a water clock capable of indicating the times of prayer. He also attempted to fly by leaping from the top of the Rusafa palace in Cordoba with a hang glider of his own invention. He apparently managed to glide for some distance but suffered injuries in a rough landing, which his critics attributed to his failure to observe the manner in which birds use their feathers when they alight on a branch.
Tenth-century Cordoba was renowned for its school of physicians, presided over by the Jewish doctor Hasday ibn Shaprut, vizier of Abd al-Rahman III and later personal physician of Hisham II. Hasday also supervised the imperial translation activities and carried out diplomatic missions on behalf of the caliphate. One of his diplomatic activities involved the reception of an ambassador from the Byzantine capital Constantinople in 949. The envoy brought with him presents for Abd al-Rahman III from the emperor Constantine VII Porphyrogenitus (r. 913-59), one of them being a superb Greek manuscript of Dioscorides’ De Materia Medica
No one in Cordoba knew enough Greek to read the manuscript, so the ambassador arranged for a Byzantine monk named Nicholas to be sent to Cordoba. He arrived in 951, along with a Greek-speaking Arab from Sicily. Nicholas and the Arab then explained Dioscorides’ work to a group of Cordoban scholars headed by Hasday thus beginning the study of pharmacology in Al-Andalus. De Materia Medica was subsequently translated from Arabic into Latin for the education of pharmacists and physicians in Christian Europe.
The principal source of information about the Cordoban medical school is Ibn Juljul al-Andalusi (944-ca. 994), who studied medicine there between the ages of fourteen and twenty-four. His most important work, entitled Generations of Physicians and Wise Men,is the most complete extant source in Arabic on the history of medicine. He says that most of the physicians practicing in Al-Andalus up to the time of Abd al-Rahman III were Mozarabs, or Christians living under Arab rule, and that the principal source of their knowledge was “one of the books of the Christians that had been translated,” which would have been Dioscorides’ work.
Ibn Juljul also wrote a treatise on Dioscorides’ De Materia Medica, probably based on the manuscript that had been sent from Constantinople. The works of Ibn Juljul remained popular in Al-Andalus for centuries, and one of them may have been translated into Latin, since Albertus Magnus quotes from a treatise that he attributes to a certain Gilgil, probably a corruption of “Juljul.”
The physician Abu'l Qasim al-Zahrawi (ca. 936-ca. 1013), the Latin Abulcasis, was a contemporary of Ibn Juljul's. He lived in the imperial Cordoban suburb of Madinat al-Zahra, his family tracing its origins back to the Arab warriors who originally conquered Al-Andalus. His only known work is the Kitab al-Tasrif, a medical encyclopedia in thirty volumes, which he completed in about the year 1000, encompassing nearly half a century of experience as a physician. The encyclopedia covers every aspect of medicine, including the design and manufacture of surgical tools, midwifery, pharmaceutical preparations, diet, hygiene, medical terminology, weights and measures, medical chemistry, human anatomy and physiology, therapeutics, and psychotherapy. Al-Zahrawi particularly emphasized the importance of bedside manner and the bond between doctor and patient, writing, “Only by repeated visits to the patient's bedside can the physician follow the progress of his medical treatment.”
Al-Zahrawi was also a pioneer in the use of drugs in psychotherapy, and he made an opium-based medicine that he called “the bringer of joy and gladness, because it relaxes the soul, dispels bad thoughts and worries, moderates temperaments, and is useful against melancholia.”
The development of astronomy in Al-Andalus begins with the work of Abu Maslama al-Majriti, who was born in Madrid and studied in Cordoba, where he died in 1007. Together with his student Ibn al-Saffar (d. 1034), he improved the astronomical tables of al-Khwarizmi and adapted them for the longitude of Cordoba, a work that passed to Christian Europe through a Latin translation by Adelard of Bath. Two other extant works of al-Majriti's are the Commercial Arithmetic and the brief Treatise on the Astrolabe,while his Arabic translation of Ptolemy's Planis-phaerium survives in a Latin version by Herman of Dalmatia. The eleventh-century historian Ibn Sa'id of Toledo says that al-Majriti “applied himself to the observation of the heavenly bodies and to understanding the book of Ptolemy called the Almagest,” and that he was “the author of a summary of the part of al-Battani's table concerning the equation of the planets.”
Another work attributed to al-Majriti is the Ghayat al-Hakim (The Aim of the Wise), which was translated into Spanish in 1256 through the patronage of King Alfonso X of Castile. It was later translated into Latin under the title Picatrix, a corruption of Buqratis, the Arab name of Hippocrates, on the supposition that he, and not al-Majriti, was the author, who is described on the title page as being a “very wise… philosopher… most skilled in mathematics … [and] very learned in the arts of necromancy.”
The Picatrix has been described as “a compendium of magic, cosmology, astrological practice, and esoteric wisdom in general” that “provides the most complete picture of superstitions current in eleventh-century Islam.” Lynn Thorndike devotes a whole chapter of his History of Magic and Experimental Science to the Picatrix, which he describes as a “confused compilation of extracts from occult writings and a hodgepodge of innumerable magical and astrological recipes.”
Al-Majriti had a number of students who spread his knowledge of both science and magic throughout Al-Andalus and even beyond, the best known being Ibn al-Samh of Granada (d. 1035), al-Kirmani of Saragossa (d. 1055), and Ibn al-Saffar. Knowledge of al-Majriti's work evidently made its way to the eastern Islamic world, for nearly four centuries later he is mentioned by Ibn al-Shatir of Damascus as one of those who had produced astronomical models that were different from the standard Ptolemaic theories.
The leading Andalusian astronomer in the century after al-Majriti was Ibn Mu'adh al-Jayyani (d. 1093), whose last name comes from the fact that he was a native of Jaén, east of Cordoba. His best-known work is the Tabulae Jahenen, a set of astronomical tables based on al-Khwarizmi's Zij al-Sindhind and adapted for the longitude of Jaén. His tables were an improvement over the Sindhind, for he took into account the precession of the equinoxes, which al-Khwarizmi had ignored, and he utilized advances in astronomical theory made by al-Biruni and his other predecessors. The Tabulae Jahenen also gives detailed instructions in such practical matters as determining the times of prayer, the direction of Mecca, the beginning of the Islamic months, and the casting of horoscopes, all of which made it very helpful for mosque astronomers.
Al-Jayyani's other writings include treatises on astronomy and mathematics. His astronomical works include a treatise dealing with the phenomena of twilight and false dawn, which in its Latin translation was popular from the medieval era until the Renaissance. One of his mathematical works is a treatise on spherical trigonometry. Another is his treatise On Ratio, which he says he composed “to explain what may not be clear in the fifth book of Euclid's writing to such as are not satisfied with it.” But there is no evidence that he did clarify the fifth book of the Elements
Al-Jayyani's treatise on spherical trigonometry was indirectly transmitted to Christian Europe through a work of Jabir ibn Aflah's, an astronomer and mathematician who flourished in Seville in the first half of the twelfth century. Ibn Aflah's most important work, in which he used and added to al-Jayyani's methods in spherical trigonometry, is an adaptation of Ptolemy's astronomical theories in a treatise entitled Islah al-Majisti (Correction of the Almagest) The Islah was translated into Latin and Hebrew, and it was used by Muslim, Jewish, and Christian astronomers and mathematicians until the seventeenth century.
Another set of astronomical tables was compiled for Toledo around 1069. These were the famous Toledan Tables, known only through a Latin translation, which survives in an enormous number of manuscript copies. The tables, which were an adaptation of earlier works from Ptolemy through al-Khwarizmi and al-Battani, were prepared by a group of astronomers, the best-known of whom was Abu'l-Qasim Sa'id (d. 1070), the qadi, or judge, of Toledo.
Another notable member of the group was Ibn al-Zarqali (d. 1100), the Latin Arczachel, a self-educated artisan who worked for Abu'l-Qasim Sa'id as a maker of astronomical instruments and water clocks. After Abu'l-Qasim Sa'id died, al-Zarqali became director of the group that completed the new astronomical tables. The Toledan Tables were used in both Al-Andalus and in Christian Europe, where they were translated into Latin circa 1140 as the Marseilles Tables They remained in use until the fourteenth century, and a Latin version of the Toledan Tables was translated into Greek, completing a remarkable cultural cycle. The tables are mentioned by Chaucer in “The Franklin's Tale,” where one of the characters is a magician-astrologer of Orleans, equipped with all the tools of his celestial trade:
His tables Toletanes forth he brought
Ful wel corrected, ne ther lacked noght,
Neither his collect ne his expans yeres,
Ne his rotes ne his othere geres.
The observations that led to the Toledan Tables were continued for another three decades by al-Zarqali, who in around 1078 left Toledo because of the repeated attacks by the Christian king Alfonso VI and moved to Cordoba, where he lived for the rest of his days. The water clocks built in Toledo by al-Zarqali remained in use until 1133, when King Alfonso VII of Castile and León had them taken apart to see how they worked but could not reassemble them. Water clocks of the type built by al-Zarqali, which showed the motion of the celestial bodies, became popular in seventeenth-century Europe.
Other works by al-Zarqali include six treatises on mathematical astronomy and astronomical instruments. One of these treatises is an adaptation of an astronomical work by Ammonius of Alexandria entitled the Almanac Al-Zarqali's elaboration of the Almanac,in which he uses Babylonian astronomy as well as drawings from the works of Hip-parchus and Ptolemy, was translated into Latin, Hebrew, Portuguese, Catalan, and Castilian, and it remained in use until the fifteenth century. Another of his astronomical treatises describes the orbit of Mercury as “oval” rather than circular, which a modern Islamic scholar has interpreted as anticipating Kepler's theory of elliptical orbits, but this seems highly unlikely.
The beginning of Arabic philosophy in Al-Andalus comes with the work of Ibn Hazm (994-1064), who was born and spent most of his life in Cordoba, where his father and grandfather had been functionaries in the Umayyad court. His best-known philosophical work is his Book on the Classification of the Sciences Aside from his many philosophical compositions, he also wrote poetry and treatises on history, jurisprudence, ethics, and theology. His most famous poetical work is entitled Tawq al-Hamama (The Dove's Neck-Ring), a treatise on the art of love, which he says is “a serious illness.”
I've a sickness doctors can't cure,
Inexorably pulling me to the well of my destruction
Consented to be a sacrifice, killed for her love,
Eager, like the drunk gulping wine mixed with poison
Shameless were those my nights,
Yet my soul loved them beyond all passion.
Ibn Hazm notes that he was particularly qualified to write a book on the art of love, having been brought up until the age of fourteen in the harem, or women's quarters, of his family home: “I have observed women at first hand and I am acquainted with their secrets to an extent that no one else could claim, for I was raised in their chambers and I grew up among them and knew no one but them.” He goes on to say that “women taught me the Koran, they recited to me much poetry, they trained me in calligraphy.”
The Islamic schools of the time in Cordoba employed scores of women copyists, as did the city's book market. More highly educated women worked as teachers and librarians, and a few even practiced medicine and law.
The next Andalusian philosopher of note after Ibn Hazm was Ibn Bajja, known in Latin as Avempace. Ibn Bajja was born in Saragossa circa 1070, and in the years 1110-18 he served as vizier to the Almoravid governor of the city, Ibn Tifilwit. After the Christian conquest of Saragossa he spent the rest of his life in Almoravid territory, living in turn in Almeria, Granada, and Seville. While in Seville he was imprisoned before being released due to the intervention of Ibn Rushd al-Jadd, grandfather of the philosopher Averroës. After his release he moved first to Jaén and then to Fez in Morocco, where he died in 1128. Tradition says that he was killed by eating an eggplant poisoned by his rivals, intellectuals in the Almoravid court in Fez.
Thirty-seven of Ibn Bajja's numerous works survive, many of them commentaries on the works of Aristotle, Euclid, Galen, and al-Farabi, along with three of his own works. His ideas influenced the thought of Ibn Tufayl (Abubacer), Ibn Rushd (Averroës), Maimonides, and, in Latin translation, Saint Thomas Aquinas.
Ibn Bajja seems to have been the first Arabic scientist in Al-Andalus to oppose the Ptolemaic planetary model. He rejected the use of epicycles as being incompatible with Aristotle's doctrine of celestial motion, in which the planets move in perfect circles about the earth, at the center.
Ibn Bajja's ideas on dynamics appear in his notes on Aristotle's Physics Here he rejected the Aristotelian law of motion, which held that the velocity of a body was directly proportional to the motive power and inversely proportional to the resistance of the medium through which it moved. Instead, following John Philoponus, he said that motion would occur only when the motive power was greater than the resistance, and that the velocity was proportional to the difference between the power and the resistance. This meant that in a void a body would move with finite speed, rather than infinitely fast. He argued further that even in a void a body had to traverse a definite distance in any given time, so that its velocity would be finite no matter how fast it was moving. This was counter to the Aristotelian notion that in a vacuum a body's velocity would be infinite, which was impossible, so that a void could not possibly exist.
Ibn Bajja was also an accomplished musician and poet. According to the thirteenth-century Tunisian writer al-Tifashi, Ibn Bajja “combined the songs of the Christians with those of the East, thereby inventing a style found only in Andalus, toward which the temperament of its people inclined so that they rejected all others.”
Abu Marwan ibn Zuhr (ca. 1092-1162), the Latin Avenzoar, was the most famous of a family of Seville physicians who served the Almoravid dynasty in Al-Andalus and the Maghreb. Ibn Zuhr served as personal physician to the amir Ali ibn Tashfin (r. 1106-43) in his palace at Mar-rakesh, but because of a misunderstanding he was imprisoned by his patron. When the Almoravids were overthrown by the Almohads, Ibn Zuhr was restored to favor by the new ruler, Abd al-Mu'min (r. 1145-63), who appointed him as his court physician and personal counselor, with the rank of emir.
Ibn Zuhr's medical writings were based on the works of Hippocrates and Galen as well as those of his Arabic predecessors and his own researches. His best-known work, An Aid to Therapy and Regimen, was translated into Hebrew and Latin and remained in use until the European Renaissance. Ibn Zuhr was generally considered to be one of the best physicians in Al-Andalus, particularly as a clinician and medical therapist.
Abu Bakr Muhammed ibn Tufayl (c. 1110-85), a student of Ibn Bajja's, was the personal physician and vizier to the Almohad caliph Abu Ya'qub Yusuf (r. 1163-84), the builder of the Great Mosque in Seville, his capital. Ibn Tufayl continued the tradition of his teacher Ibn Bajja in opposing the Ptolemaic planetary theory. He apparently formulated a planetary model that avoided using the eccentrics and epicycles of Ptolemy. Ibn Tufayl was the first Andalusian thinker to make use of the works of Ibn Sina, though with some differences, such as his belief that there is no proof that the world is eternal rather than created in time.
The culmination of Arabic philosophy comes with Ibn Rushd, the Latin Averroës (1126-98), who was from a distinguished family of Cordoban jurists. He was named for his grandfather, who was imam of the Great Mosque and also qadi, a position his father also held. He studied theology, law, medicine, and philosophy, including the works of Aristotle, particularly his writings in physics and natural science.
Ibn Rushd was in Marrakesh in 1152, during the reign of the Almohad ruler Abd al-Mu'min, when he seems to have made his first astronomical observations. There he may have met Ibn Tufayl, who would later play an important part in his life by introducing him to the caliph Abu Ya'qub Yusuf. According to Bun dud ibn Yahya, a disciple of Ibn Rushd's, the caliph had complained to Ibn Tufayl about his difficulty in reading the works of Aristotle and the need for a commentary to explain them. Ibn Tufayl said that he himself was too old and busy to do the job, and so he recommended Ibn Rushd, who was thus led to begin his monumental commentary on the works of Aristotle.
After the death of Ibn Tufayl, Ibn Rushd became the personal physician to Abu Ya'qub Yusuf and was appointed qadi, first in Seville, then in Cordoba, and then again in Seville. He retained his posts under Abu Ya'qub Yusuf's son and successor Abu Yusuf Ya'qub al-Mansur (r. 1184-99), though in 1195 the caliph confined him for two years to the town of Lucena, near Cordoba, because fundamentalist Islamic scholars had condemned his philosophical doctrines. Early in 1198 the caliph lifted the ban and took Ibn Rushd with him to his court at Marrakesh. But Ibn Rushd had little time to enjoy his freedom, for he died in Marrakesh on 10 December of that year, after which his body was returned to Cordoba for burial.
The philosophical writings of Ibn Rushd can be divided into two groups: his commentaries on Aristotle and his own treatises on philosophy, entitled Decisive Doctrine About the Concordance Between Revelation of Religion, Exposition of the Methods of Demonstration, and Incoherence of the Incoherence of the Philosophers The last treatise was written in opposition to al-Ghazali's attack on rational philosophy, particularly the works of al-Farabi and Ibn Sina, the two leading Muslim interpreters of Aristotle. Here, in his defense of Aristotelianism, Ibn Rushd shows how al-Farabi and Ibn Sina often deviated from the ideas of Aristotle, trying to resolve the dispute between Islamic theologians and philosophers and to reconcile apparent contradictions between Scripture and science. His commentaries attempted to restore Aristotle's own ideas in Islamic thought and to supplant the Neoplatonism of al-Farabi and Ibn Sina. He regarded the philosophy of Aristotle as the last word, to the extent that truth can be understood by the human mind.
Ibn Rushd's writings deeply influenced Maimonides and, through him, other Jewish scholars, who read his works in Arabic. 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.”
Following earlier Arabic philosophers, 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. Each of the eight spheres—those of the stars, sun, moon, and five planets—has its own incorporeal intelligence, which serves as what Ibn Rushd calls its “own object of desire,” since each performs its own unique motion.
Ibn Rushd 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.
In his commentary on Aristotle's Physics, Ibn Rushd attacked Ibn Bajja's theory of motion, specifically the idea that the medium impeded natural motion. Instead he supported Aristotle's theory, in which the velocity of a body is proportional to the force acting on it divided by the resisting force of the medium. Actually, both theories are incorrect; the first correct explanation came with Newton's laws of motion in 1687.
Ibn Rushd's major work on medicine is his Al-Kulliyyat (Generalities), which is based on the writings of Galen. He was a very close friend of Ibn Zuhr, who dedicated his Al-Taisir to him Ibn Rushd's Al-Kulliyyat and Ibn Zuhr's Al-Taisir were meant to constitute a comprehensive medical textbook, and some Latin editions contain both treatises bound together as a single book, which in some places supplanted Ibn Sina's Canon 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 Platter (1536-1614).
Ibn Rushd was the first writer in any language to complain about discrimination against women, which he felt was one of the most serious problems in Muslim society.
Our society allows no scope for the development of women's talents. They seem to be destined exclusively to childbirth and the care of children, and this state of servility has destroyed their capacity for larger matters. It is thus that we see no women endowed with moral virtues, they live their lives like vegetables, devoting themselves to their husbands. From this stems the misery that pervades our cities, for women outnumber men by more than double and cannot procure the necessities of life by their own labors.
Ibn Tufayl's researches in astronomy were continued by his student al-Bitruji (fl. ca. 1190), the Latin Alpetragius, whose only known work is his Kitab fi'l-Hay'a (Book of Astronomy). Al-Bitruji acknowledged that Ptolemy's theory gave an exact mathematical description of planetary motion. But he felt that the Ptolemaic model was unsatisfactory since its eccentrics, epicycles, and equants were incompatible with Aristotle's physical concept of the homocentric spheres. And so he tried to formulate a model in which a simple system of concentric spheres, one for each planet, would give results equivalent to those of Ptolemy's theory.
The Kitab fi'l-Hay'a was translated into Hebrew and Latin, leading to the spread of al-Bitruji's ideas through much of Europe from the thirteenth century into the seventeenth. Al-Bitruji's planetary model was used by those who defended Aristotle's theory of the homocentric spheres against the supporters of Ptolemy's eccentric epicycles and equants. Isaac Israeli (fl. 1310) of Toledo seems to be referring to al-Bitruji when he writes of “the man whose theory shook the world.” Copernicus refers to al-Bitruji in connection with the order of the planets Mercury and Venus in his heliocentric theory of 1543.
After the fall of Cordoba to the Christians in 1252, western Arabic science continued in Granada, the last Muslim kingdom in Al-Andalus, and in the Maghreb, though on a much diminished scale.
The mathematician Ibn al-Banna al-Marrakushi (1256-1321) was a native of Granada, though, as his last name indicates, he seems to have spent most of his life in Marrakesh. He is known to have studied in both Marrakesh and Fez, where he taught mathematics and astronomy in the madrasa al-Attarin. Eighty-two of his works are known, of which the most important is the Summary of Arithmetical Operations, a compendium of the lost works of the mathematician al-Hassar (fl. ca. 1200).
Al-Qalasadi (ca. 1412-ca. 1506) is the last Arabic mathematician known to have lived in Al-Andalus and the Maghreb. He was a native of Basta (now Baza) in Spain, but when the city was taken in 1486 by Queen Isabella of Castile he was forced to flee to the Maghreb, where he died at Beja in Tunisia. One of al-Qalasadi's works is a commentary on Ibn al-Banna's Summary of Arithmetical Operations The first of his own writings was the Classification of the Science of Arithmetic, which he followed with a simplified version entitled Unveiling the Science of Arithmetic, and then an abridgment of this work called Unfolding the Secrets of the Use of Dust Letters (i.e., Hindu numerals). The last two works were used in Moroccan schools for generations after the death of al-Qalasadi.
Al-Qalasadi died only a few years after the fall of Granada in 1492, which ended the history of Al-Andalus. The principal remnant of the intellectual world of Muslim Granada is the Casa de la Ciencia (House of Science), founded in 1349 by the amir Yusuf I (r. 1334-54). Only fragments of the Moorish building remain, but it is still referred to by its original Spanish name, La Madraza, from madrasa, the Arabic word for a Muslim school of higher studies, the last one in Al-Andalus. La Madraza was the predecessor of the University of Granada, founded in 1531 by the emperor Carlos V, as Christian Spain picked up the study of science from where it had been advanced by Muslim Al-Andalus.