Time Table (Dates Are C

Islam's Contribution to Western Learning Dr. J. L. Berggren, SFU 11 February 2002

Historical Persons/Events Date Muslim Figures Charlamagne 820 Caliph al-Ma’mun (translations) 825 Al-Khwarizmi (Arithmetic & Algebra) Alfred of England 880 The Banu Musa - Geometry 890 Al-Battani - Astronomy 890 Abu Kamil – Arithmetic and Algebra 905 Al-Razi (Rhazes) - Medicine Gerbert becomes Pope Sylvester 990 Maslama al-Majritii - Astrolabe II Leif Ericson’s voyages 1005 Ibn al-Haytham - Optics 1020 Ibn Sina (Avicenna) Saladin defeats the crusaders 1200 Al-Jazzari (engineering) Cathedral at Chartres completed 1240 Nasir al-Din al-Tusi

It began, according to a charming story, with the dream of one man, the great caliph al-Ma’mun, who reigned in Baghdad from 813 - 833. This caliph was the son of Harun al-Rashid, a patron of the arts whose fame has come down to us in the tales of the Thousand and One Nights. Brought up in an educated environment al-Ma’mun was a learned man. He knew well the traditional Muslim studies, but in addition to these he was passionately interested in the learning of the Greeks. The problem with this, from the point of view of some Muslim traditionalists, was that Greeks such as Aristotle and Euclid were not Muslims. They were not even Christians, who were, along with the Jews, one of the protected peoples in Islam. They were pagans. And what could such people have to say that was of value to a Muslim community? Indeed, there was good reason to suppose that what they had to say could, in many instances, be harmful to the Muslim faith. But, in his dream, the caliph saw the Greek sage, Aristotle, and Aristotle reassured him that religion and learning were not enemies, that al- Ma’mun’s support of foreign learning was not a threat to Islam.i Berggren Islam's Contribution to Western Learning 5/8/18 p. 2

Thus reassured, Ma’mun went on, in the year before he died, to one of his great achievements - the founding of the Bayt al-Hikma, the House of Wisdom. In this scholars from all over al-Ma’mun’s empire, and professing many faiths, studied, translated, and disseminated wisdom and learning, from whatever source it might come. Mohammad had said, “Seek learning, even in China,” and scholars at the House of Wisdom studied and translated ancient Greek, Syriac and even Sanskrit manuscripts into Arabic - the language Allah had honored by making it the vehicle of His most recent – and final – revelation, the Holy Quran. Here scholars of many faiths labored to build up one branch or another of that great Islamic enterprise: ‘ilm.’. This is a word which, unfortunately, has no real English, equivalent. We use the word ‘science,’ lacking a better word, but the French noun ‘savoir’ or the German ‘Wissenschaft’ better catch the broad sense of the Arabic word whose basic meaning is ‘an organized field of knowledge.’ I shall use the word ‘learning.’ There was only one Arabic word for it, but ‘learning’ was in Medieval Islam recognized as having two main divisions: the religious and the ancient. Included in religious learning were such areas of study as the correct reading of the Quran and its interpretation, the traditions regarding the words and deeds of the prophet and his companions, theology, law, etc. The foreign sciences included philosophy, astronomy and astrology, mathematics, optics, geography, map making, etc. They were also known as the sciences of the ancients and the first contribution of Islam to the development of Western learning was the translation of a huge corpus of Greek philosophical and scientific learning into Arabic. Among the works translated were the writings of the philosopher, Aristotle, the medical practitioner, Galen, the geometry of Euclid, advanced geometrical works of Apollonius and Archimedes, and the astronomy of Ptolemy. Among other things these translations resulted in the creation of Arabic philosophical medical, mathematical, and astronomical vocabularies. All of these works were available in the twelfth century, the great century in which so much of Arabic learning was transmitted to the Latin west. Among the translators was William of Berggren Islam's Contribution to Western Learning 5/8/18 p. 3

Moerbecke, Robert of Chester, and Plato of Tivoli. This transmission of the Greek classics was a major Islamic contribution to the development of learning in the west. However, this was not the only contribution. Medieval Islamic scholars not only copied the works, but they studied them as well. They wrote commentaries on them, they composed lecture courses to teach them, and they criticized and improved on them. This was a massive enterprise, extending over 600 years, and it too contributed to the development of Western learning, for it was not just the Greek classics that the West acquired from Arabic texts. It was also treatises with new ideas. Al-Khwarizmi One of the first of these new ideas was a system of counting and arithmetic, namely the system we use today. The man who introduced this to Islam and the West was Muhammad ibn Musa al-Khwarizmi al-Majusi, who worked in Baghdad at the time of al-Ma’mun. His ancestors were Zoroastrians, but his name indicates that he, at least, was Muslim, one who came from the region of Khwarizm. This was located around the delta of the Oxus River at the Aral Sea [MAP FOR OVERHEAD] and had been a center of ancient civilization before Muslim armies conquered it. He wrote fundamental works for four different sciences: arithmetic, algebra, astronomy and geography. And, in the first three of these, his work was widely influential in the west. In arithmetic he has to his credit the introduction the base 10 positional system (complete with 0) for the representation of whole numbers. He acknowledges that the Hindus were the ones to discover this system, but his treatise, Addition and Subtraction According to the Hindu Method of Calculation, was the first Arabic arithmetic treatise on it and the first to be translated into Latin. It gave us not only our system of arithmetic but the word ‘algorithm’ (a corruption of his name) as well. Despite its title, which speaks only of addition and subtraction, the work explains how to do all four operations of arithmetic in the new system, as well as the extraction of square and cube roots and an Berggren Islam's Contribution to Western Learning 5/8/18 p. 4 ingenious system of fractions. Its translation made obsolete the cumbersome system of Roman numerals, which had dominated western mathematics up to the twelfth century. It gave Latin scholars the means for dealing with the numerical tables in the astronomical texts that they were translating from Arabic into Latin at the same time. These tables were vastly more sophisticated than the simple tables used in the West for the computation of the date of Easter, and they siimply would not have been accessible without the work of al-Khwarizmi. Like his arithmetic, al-Khwarizmi’s Algebra also gave the west a new word, ‘algebra’, and its first treatment of that subject. Indeed, he gave the subject its name. But it was not just a text with rules to memorize and apply without understanding. Rather, al-Khwarizmi included demonstrations of the validity of his methods for solving equations. In the hands of al-Khwarizmi algebra had become ‘ilm – not just a collection of facts but an organized discipline of thought. It is quite appropriate that al-Khwarizmi should have dedicated such an important work to the Chalif, al-Ma’mun. Al-Khwarizmi also authored a set of astronomical tables for solving problems in astronomy. In addition to solving the standard problems on finding the true positions of the planets, the sun, and the moon at a given time he also solved the problem of finding the dates of the new moons. This was not done in Greek astronomy since the date of the new moon was not important for them. But for the Muslims the new moon marked the beginning of the new month, and an ability to predict the date of the next new moon had obvious social utility. Also in the book are discussions of astrology, a subject that interested many Muslim rulers. Al-Khwarizmi computed his tables for the longitude of a locality in India known as Arin, now called Ujjain, located on the Summer Tropic at a longitude 76° east of Greenwich.1 Some 250 years later a Muslim astronomer in Madrid, redid the tables for the longitude of his home town, Cordova. In this form the tables were translated into Latin by Adelard of Bath in the early 12th century, and these, too, were basic for late-medieval Western science.2

1 Al-Khwarizmi took Arin to be the mindpoint of the hemisphere extending from pole to pole and from the Western Ocean to the Eastern Ocean. Berggren Islam's Contribution to Western Learning 5/8/18 p. 5

The Banu Musa These were three brothers, Muhammad, Ahmad, and al-Hasan, whose father had been, variously, a successful highway robber and, later, a court astrologer. At his death he left his sons in the care of the caliph, al-Ma’mun, who ensured that they were brought up with a good education.In fact they were placed under the tutelage of an astrologer at the Bayt al-Hikma. In later life they became quite wealthy and influential, and stories are told of how they used this influence to have scholars that they did not like punished. For all their intrigues, however, they were accomplished scholars and spent much of their wealth acquiring and having Greek manuscripts translated, one of these being a classic work of advanced geometry, known as the Conics, by Apollonius of Perga. [Extract from Preface, explaining their struggle to understand the work.] Their most important work in terms of our topic today is the work On the Measurement of Plane and Solid Figures, which developed ideas in Archimedes’s works. The Latin translation of this work3 by Gerard of Cremona played an important role in introducing geometrical ideas into Europe and in the next century. It influenced the famous Leonardo Fibonacci of Pisa at the end of the 12th century. They (probably mostly Ahmed) also wrote a work called On Ingenious Mechanical Devices, containing descriptions of 100 such devices, and we shall refer to this later. Al-Battani He was one of the many famous Muslim scientists who came from Harran and belonged to a religious sect that al-Ma’mun encountered on his military campaigns in that area, known as the Sabians. These were star worshippers and so, technically, should have converted to Islam or face death. Some, indeed, were compelled to convert, but eventually the Muslims decided that these people, who called themselves Sabeans, were the people of the Queen of

2 The study of these old documents can sometimes yield unexpected results, one example being Neugebauer’s discovery that a method discovered by J. Kepler for approximating certain important astronomical parameters (specifically, parallaxes) is identical with that discovered a thousand years before Kepler’s time by Hindu astronomers in India. 3 The book was known in that language as the Liber trium fratrum de geometria. Berggren Islam's Contribution to Western Learning 5/8/18 p. 6

Sheba. As a people mentioned in the Bible they then became a protected religious group and many of them enjoyed distinguished careers in the chalif’sl court while retaining the faith they were born into. The name of our author (Muhammad) shows, however, that he was a Muslim, and he became one of the greatest Muslim astronomers. Three of his four known works are on astrology, and this is further evidence of the popularity of that subject in medieval Islam. Although he was probably born in Harran, sometime before 858, he lived all his life in Rakka – on the left bank of the Euphrates River – in a colony of immigrants from Harran. He knew, of course, Ptolemy’s great astronomical classic, the Almagest, but he devoted his life to astronomical observations to check, correct, and improve the parameters given in that work. Among these were observations that resulted in highly accurate determinations of the obliquity of the ecliptic, the length of the tropical year, and the lengths of the seasons. Al-Battani’s fourth known work is his set of astronomical tables. In addition to providing new tables and solutions to standard astronomical problems, the work gave new methods for determining the beginnings of the Muslim months, as well as an approximate method for determining the direction of Mecca. This was now another important way in which science could prove itself to be useful to Islam, since the direction of Mecca was the direction the believer was to face for the five daily prayers. A number of translators produced Latin translations of his tables, the latest being that in the 13th century by Alfonso X of Castille. These translations influenced Jewish and Christian astronomers in the West, including Abraham bar Hiya and Regiomontanus. Abu Kamil Other than his Egyptian origin nothing is known of his life. He followed al- Khwarizmi in algebra and extended his system from the second power of the unknown to the eighth. He also provided a correct statement of the law of signs for multiplying algebraic quantities. Berggren Islam's Contribution to Western Learning 5/8/18 p. 7

Like al-Khwarizmi, he also wrote on arithmetic, and his Rarities of Arithmetic was translated into Hebrew and Latin. His Algebra was also translated into these two languages, and it had a considerable influence on Fibonacci. Al-Razi (865 – 925) Abu Bakr al-Razi was born in Iran. He was an accomplished musician, who also studied philosophy. Eventually, however, he decided on the study medicine, and he went to a hospital in Baghdad to gain experience. He then returned to al-Rayy, near modern Teheran, to become director of its hospital. After another trip to Baghdad in the early 890s, where he wrote a book on his hospital experiences, he returned to Rayy where he became physician to the governor, al-Mansur. To this patron he dedicated two books, his al-Tibb al- Mansuri, and his At-tibb al-ruhani. The first dealt with physical ills and the second with psychological ills. Al-Biruni, one of the great Muslim polymaths, catalogued 184 of his works, mostly on medicine. His works are rich in observatioin, and although he knew the Greek medical literature of Hippocrates and Galen well he also criticized parts of it and insisted on checking opinions by experience. He insisted on the use of previously tested drugs, he urged continuing study for physicians, and he fought quacks and charlatans in medicine. (He also warned patients that changing from one doctor to another would waste their wealth, health, and time!) Three of his books that were translated into Latin were (1) The Book of al-Mansur (Liber almansoris, by Gerard of Cremona), (2) the Inclusive Treatise on Medicine, a huge work translated by the Jewish physician Faraj ibn Salim in 1279 under the title Continens, and (3) a treatise on smallpox and measles. He was known in the Latin west as Rhazes. He was an indefatigable worker, and the following account from his writings testifies to this passion for learning: “As for my love of learning and my desire and passionate endeavour to possess it, it is well known amongst my friends and those who have observed me at it that I have never ceased since my yourth up to this present time to be intent upon learning; so much so, that whenever I have chanced upon a book which I have Berggren Islam's Contribution to Western Learning 5/8/18 p. 8 not read, or a man whom I have not hitherto met, I have not heeded any other occuptation—even though it has been to my great loss—until I have mastered the book and found out all that the man knew. So vast indeed have been my patience and endeavour that I have written, in a minute script like that in which amulets are inscribed, more than 20,000 sheets within a single year. I was engaged contiinuously upon the great Compendium for fifteen years, working night and day, until my sight grew dim and I was affected by a paralysis in the muscles of my hand, so that at the present time I am disabled from reading and writing. Yet I still continue these two occupations to the utmost of my power, and always engage the assistance of someone to read and write for me.” As for the dimness of sight he refers to, when an oculist suggested an operation al-Razi remarked, “I have seen enough of this old world, and I do not cherish the idea of suffering the ordeal of an operation for the hope of seeing more of it.” In tribute to his contributions, one of the stained glass windows of the Princeton U. Chapel has his portrait, along with the Arabic title of one of his great works, the Inclusive Treatise. Berggren Islam's Contribution to Western Learning 5/8/18 p. 9

Ibn al-Haytham (965 – 1020) Born in Basra, Iraq he went to Egypt at the request of its ruler, al-Hakim, to implement his scheme for controlling the flooding of the Nile. On his arrival he saw that the scheme would not work and confessed as much to al-Hakim, who, however, gave him another government post. However, al-Hakim was, to put it mildly, unstable, and Ibn al-Haytham decided to feign insanity. When al-Hakim died Ibn al-Haytham recovered and spent the rest of his days at al-Azhar, the famous mosque and center of teaching. According to one account he earned a living copying out, once each year, He discovered a universal solution to the problem of finding the qibla of Mecca and he wrote on the construction of mirrors that would cause burning. and he composed a treatise on the structure of the cosmos (“The Configuration of the World”). This addressed a philosophical problem with Ptolemy’s theory of the cosmos which had bothered Islamic thinkers for some time. This was translated several times into Latin, and influenced Georg Peuerbach, a noted astronomer who was a contemporary of Copernicus. However, Ibn al-Haytham is most famous for his investigation of optics, which to meant the science of vision. This work combines optical theory, experiment, and mathematical proofs and deals with everything from the geometry of vision to the psychology of vision, including optical illusions. Oddly enough, The Optics appears to have made an impression in the West before it was appreciated in Ibn al-Haytham’s own country. Latin authors were citing the work in the early 13th cengtury but seems to have been neglected in the East the Persian Kamal al-Din wrote a large commentary on it. Federicus Risner printed the Latin in 1572 under the title Opticae thesaurus. The work was a major influence not only on the thirteenth-century philosopher Roger Bacon but also on Kepler (d. 1630) and his contemporaries. Ibn al-Haytham's work on parabolic mirrors was translated by Gerard of Cremona (d. 1187). Maslama al-Majriti I have not yet said much about learning at the other, western end of the Muslim world, in al-Andalus and the Maghreb, and it is time remedy this. In al-Andalus, Berggren Islam's Contribution to Western Learning 5/8/18 p. 10 roughly modern Spain, in the 10th century one of the most learned of men was Maslama al-Majriti. As his name indicates, he came from Madrid, but he did much of his work in Cordova and died there about 1007. He was trained in geometry and the foreign sciences in Cordova, but he clearly was well trained in the Islamic sciences as well since one of the nicknames he had was ‘the determiner of shares (al-faraDii),’ that is to say one who determines the shares of the legal heirs to an estate under the complicated arithmetic rules of Islamic religious law. This is entirely consistent with his having written a commercial arithmetic, dealing with sales, valuation and taxation. He was also known as an astrologer, and probably was court astrologer for the court in Cordova. However, he was also an astronomer since he carried out observations in 979 and adopted the tables of al-Khwarizmi for the longitude of his city. We mention him here, however, for his connection with the history of the astrolabe. This instrument, invented in Hellenistic Greece, became the pocket watch of the medieval traveller. With the modifications to its design introduced by Muslim astronomers in the course of the centuries it could be used for astronomical observations, time keeping, trignometrical calculations, and even finding the direction of Mecca. It was equally important in late medieval western astronomy, and there is some evidence that it entered Europe through Barcelona and the work of Gerbert, who later became Pope Sylvester II. In any case, Maslama not only wrote a treatise on the technical details of the construction and use of this instrument but he also translated the fundamental treatise of Ptolemy on the construction of the instrument. Maslama’s Arabic translation was then translated into Latin by Hermann of Dalmatia in 1143 and into Hebrew. Maslama edited, as well, a commentary on the text. The standard astrolabe which Ptolemy described was limited to use in a particular latitude, and if one went north or south any appreciable distance one had to have a different plate. For this reason astrolabes were made with a set of plates, each usable at a different latitude. However, an two astronomers of Toledo, Abu’l-Hasan Ali ibn Khalaf and al-Zarqallu, both of them active in the late Berggren Islam's Contribution to Western Learning 5/8/18 p. 11

11th century, invented astrolabes that could be used for any latitude. These ‘universal’ astrolabes (as they have been called) were made known to the Latin west through translations in the Libros del Saber, a collection of works on astronomy and astrology assembled and translated in 1277 from the Arabic by Jewish scholars working under the patronage of Alfonso X (‘The Wise”) of Castille. These new astrolabes appeared, then, in a number of European books published in the mid-to-late 16th century. Ibn Sina (Avicenna 980 - 1037) No one would ever accuse Abu Ali Ibn Sina of false modesty, but he could – with some justice – reply that he had so little to be modest about! He grew up in Bukhara and by the time he was in his teens he had memorized the Qur’an, mastered the religious sciences, and studied such foreign sciences as logic, mathematics and astronomy. He become a practicing physician at the age of sixteen, and entirely characteristic of him is his remark: “Medicine is not a difficult science, and naturally I excelled in it.” He also studied Greek philosophy in a desire to learn all there was to know and it was only when he came to Aristotle’s Metaphysics that he came to a grinding halt. For the first time in his life he had hit a book of which he wrote that he ‘could not understand the contents,’ even though he had read it over forty times and had the word by heart. He describes how he had given up on it until he came on a bookseller in the market who was offering for sale a book on metaphysics. The bookseller urged him to buy it, saying that it would solve his difficulties and, since the owner needed the money, he would sell it cheaply.” Ibn Sina bought the book, which happened to be al-Farabi’s On the Objects of Metaphysics, and hurried home to read it. In his own words, “At once the objects of that book [of Aristotle] became clear to me, for I had it all by heart. I rejoiced at this, and upon the next day distributed much in alms to the poor in gratitude to Almighty God.” Avicenna’s two greatest works are his medical encyclopedia, of almost a million words, the Canon, and the Book of Healing. Both works were translated into Latin in the twelfth century, though the Book of Healing was translated only Berggren Islam's Contribution to Western Learning 5/8/18 p. 12 in part.. The Canon was the Islamic world’s major reference work in medicine until the nineteenth century and served the West in the same capacity for over 600 years. The Book of Healing one historian has described as ‘perhaps the longest treatise on philosophy ever written by one man.’ Another historian (S.H. Nasr) says in the article in the Britannica, of its influence in the west, that ‘his thought, blended with that of St. Augustine, . . . ,was a basic ingredient in the thought of many of the medieval Scholastics, especially in the Franciscan schools.” Al-Jazzari (1140? – 1210?) His name, Ismail b. al-Razzaz al Jazari, indicates that he lived in Mesopotamia, between the upper reaches of the Tigris and Euphrates Rivers. He worked during the time that Saladin had gained control of that area, though he was patronized by members of the Artuqid Dynasty, who at that time were little more than vassals of Saladin. However, their prudent decision to recognize Saladin’s sovereignty meant peace for them and their subjects, and this meant that al- Jazari had a much more peaceful life for doing his work than did Ibn Sina who had the misfortune to live in ‘interesting times.’ Al-Jazari is author of a work called The Book of Ingenious Mechanical Devices, which is a detailed description of how to make devices for all sort of purposes, ranging from simple amusement or creating wonder in those who see them to timekeeping devices, such as waterclocks. This tradition in the Islamic world goes back at least to the Banu Musa in the ninth century, whom I mentioned above. Arabic authors had translated the work of such Greek writers in this area as Heron and Philo, and had developed even geared calendars that would show the phases of the moon. A waterclock with elaborate mechanism was even presented to Charlemagne by vassals of Harun al-Rashid in the early ninth century, and al-Zarqaalu, whom we mentioned above, constructed a water clock on the banks of the Tagus in Toledo ca. 1050. Islamic engineers contributed to the development of civil engineering (including the construction of dams, bridges, and roads), mechanical engineering (water raising machines and water and wind powered devices), and the fine technology of instruments, Berggren Islam's Contribution to Western Learning 5/8/18 p. 13 automata and clocks. In al-Andalus, a century before al-Jazari, a writer named al- Muraadii. The text is so badly damaged as to be almost incomprehensible, but fortunately there are clear descriptions of both segmental and epicyclic gears used to deliver high torque in devices driven by full-size water wheels. Islamic water-clocks are described in a treatise translated in the Libros del Saber, but the true story of the history of water-clocks in medieval Europe has not been written. Not all of it was dependent on Islamic sources, but some of it certainly was. As Donald Hill wrote in his A History of Engineering in Classical and Medieval Times (p. 242) “The problem of the origin of medieval European water-clocks is unresolved. They may derive from early transmissions from islamic sources, or may continue the later Roman tradition of the anaphoric clock. Given the tradition for constructing and writing about water-clocks in Islamic Spain, however, a diffusion from Islam seems likely. The stimulus could, of course, have come from both sources.” Nasir al-Din al-Tusi (1201 – 1272) He was astrologer for the Assassins and then for Hulagu Khan, the Mongol whose conquest of Baghdad caused the river to run red with blood. He was also an astronomer, mathematician, and philosopher, whose writings on ethics are much studied by Islailis today. He was the director of an astronomical observatory in Maragha, and wrote the first text on trigonometry as a discipline independent of astronomy, anticipating Regiomontanus by about 200 years. He also produced not only new instruments but new astronomical models which were intended to address a fundamental Muslim criticism of the models of Ptolemy. (You may recall my mentioning Ibn al-Haytham’s criticisms around the year 1000.) The mathematical details of these models are in some cases identical to those employed by Copernicus. So far no direct link has been found, but the models known at Maragha were available in Constantinople and known to some Byzantine scholars. It is quite possible that this knowledge went with some of these scholars when they fled Byzantium for Italy after it was captured by the Turks in 1453. Many modern historians would not be a bit surprised to find that in fact the Berggren Islam's Contribution to Western Learning 5/8/18 p. 14 models of Copernicus originated in material that derived originally from a product of the Maragha school.

Suggestions for Further Reading J. L. Berggren. Episodes in the Mathematics of Medieval Islam. Springer-Verlag (1986). ISBN 0-387-96318-9 The first chapter of this book is about the people and civilization, and contains brief biographies of such figures as al-Khwarizmi and Omar Khayyam. The next three chapters discuss arithmetic, geometry, and algebra. J. R. Hayes (ed.). The Genius of Arab Civilization: Source of Renaissance. Cambridge, Mass.: The MIT Press (1978) ISBN 0-262-58035-7. This sumptuously produced paperback, with beautiful pictures and articles by leading experts in their fields, has chapters dealing not only with the topics discussed in my talk but with literature, philosohy and history, architecture and art, and trade and commerce. A.J. Arberry. Aspects of Islamic Civilization: As depicted in the original texts. New York: A.S. Barnes and Co., Inc. (1964) The material in the fifth chapter “Science from the West [i.e. Greece] is especially relevant to the material in this lecture. S. H. Nasr. Islamic Science: An illustrated study. London: World of Islam Festival Publishing Company (1976). Beautiful illustrations of all aspects of science, produced as a companion volume to the exhibit on Science and Technology in Islam at the Science Museum in London. The author has a very definite point of view on Islamic science, one not shared by most Western scholars in the field. Dictionary of Scientific Biography. New York: Charles Scribner’s Sons (1970 – 76) Available in the reference sections of most libraries this contains authoritative biographies of outstanding Muslim scientists and their influence on Western learning. Although much has been discovered about the work of many of the figures appearing in this collection since the series was completed in 1976 these biographies are still a good place to begin further reading. i The article in EI2 on al-Ma’mun (esp. 336b) makaes it plain that whatever Ma’mun may have seen in a dream he had a definite political interest in an Islamic movement known as mu’tazilism, and Greek philosophy provided additional arguments to support this movement.