The Islamic era began in 622 with the Prophet Muhammad's flight from Mecca to Medina. Led by the first caliphs, Arab forces conquered Syria in 637, Egypt in 639, Persia in 640, Tripolitania in 647, and northwest Africa in 670. An Arab fleet attacked Constantinople in 674, subjecting the city to an unsuccessful four-year siege. Within the next half century the armies of Islam conquered Sind (a province of western Pakistan) and Transoxiana (in central Asia) and invaded Spain, raiding across the Pyrenees until they were finally stopped by Charles Martel in 732 at the Battle of Tours, in France.
Mu'awiya, leader of the Umayyad clan, assumed the caliphate at Jerusalem in 661, whereupon he immediately moved to Damascus. This was the beginning of the Umayyad dynasty, whose caliphs ruled mostly from Damascus. In 749, after a four-year civil war, the Umayyads were overthrown and Abu'l-Abbas al-Saffah became caliph, thus founding the Abbasid dynasty, which would last for more than five centuries. Abu'l-Abbas was succeeded in 754 by his brother Abu Jafar al-Mansur, who in the years 762-65 built Baghdad as his new capital, beginning the most illustrious period in the history of Islam.
Baghdad emerged as a great cultural center under al-Mansur (r. 754-75) and three generations of his successors, particularly al-Mahdi (r. 775-85), Harun al-Rashid (r. 786-809), and al-Ma'mun (r. 813-33). 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, Neo-Persian, and Syriac.” Al-Mas'udi says that al-Mansur “was the first caliph to favor astrologers and to act on the basis of astrological prognostications.” He notes that the caliph had three astronomers in his court who also served as astrologers: Nawbaht the Zoroastrian, Ibrahim al-Fazri, and Ali ibn Isa the Astrolabist.
Nawbaht was the first court astrologer of al-Mansur, and his examination of the celestial signs led him to advise the caliph to begin the construction of Baghdad on 30 July 762. Ibrahim al-Fazari, the first court astronomer of the Abbasid caliphs, worked on problems of calendar reform. Ali ibn Isa is credited with being the first in Islam to make an astrolabe, an ancient Greek astronomical instrument much used by Islamic astronomers. He was also a physician, famous for his Notebook of the Oculists, the earliest important Islamic treatise on the structure and illnesses of the eye.
Nawbaht was succeeded as court astrologer by his son Abu Sahl ibn Nawbaht, the author of Kitab an Nahmutan This was the first book in Arabic on astrological history, a dynastic chronicle in terms of cyclical periods of varying lengths governed by celestial bodies. He writes, “The people of every age acquire fresh experience and have knowledge renewed for them in accordance with the decree of the stars and the signs of the zodiac, a decree which is in charge of governing time by the command of God Almighty.” Abu Sahl's motive was to show that the Abbasid succession was preordained by the stars and God, and that it was now their dynasty's turn to renew knowledge.
Theophilus of Edessa (d. 789), a Nestorian Christian who was al-Mahdi's court astrologer, called astrology the “mistress of all sciences,” because of the importance of astrological history to the Abbasids and the commissioning of horoscopes by the caliphs. Ptolemy's Tetrabibbs, the foremost astrological work of antiquity, was translated from Greek to Arabic by the Christian scholar al-Bitriq during the reign of al-Mansur.
The most prominent astrologer in the early Abbasid period was Mash'allah, a Jew from Basra who was one of those whose examinations of the celestial signs led to the founding of Baghdad. His horoscopes can be dated to the period 762-809, and he served as astrologer to all of the caliphs from al-Mansur to al-Ma'mun. He wrote on every aspect of astrology, his most interesting work being his astrological history. His works were translated into Latin, and he is referred to by Copernicus.
Jabir ibn Hayyan (ca. 721-ca. 815), known in the West as Geber the Wise, is renowned in the Muslim world as the founder of alchemy. He was born in Kufa in southern Mesopotamia and in his later years moved to Baghdad, where he became the court astrologer of Harun al-Rashid. The Gabiran corpus represents virtually all that is known of alchemy in Islam during the early Abbasid period. A basic concept of Islamic alchemy that had been inherited from the ancient Greeks was the notion that materials like sulphur and mercury could be transmuted into gold. Islamic alchemy also involved astrology, astral cosmology, magic, and other occult sciences. These branches of learning came under the heading of the “hidden” (khajiyyah) sciences, in contrast to the “open”(jaliyyah)sciences such as mathematics.
Another reason for translating Greek works into Arabic 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. It was Greek science that could provide the necessary textbooks.
Al-Mansur suffered from dyspepsia, or chronic indigestion, and soon after he moved into his new capital he sought the aid of the physicians at the Jundishapur medical school. His ailment was cured by the director of the hospital, Gurgis ibn Buhtisu, a Nestorian Christian, who came to Baghdad to serve as al-Mansur's personal physician. The Buhtisus became the leading practitioners of medicine in Baghdad, several generations of them serving as personal physicians to the caliphs. The historian Ibn Usaybi'a reports that al-Mansur commissioned many translations of Greek works from Gurgis ibn Buhtisu. The translations would have been done from Syriac by Nestorian scholars from Jundishapur, whose medical center was eventually transferred to Baghdad, becoming the first hospital and Islamic school of medicine in the Abbasid capital.
The translation program continued under al-Mansur's son and successor al-Mahdi. The new caliph's vizier, Yahya ibn Khalid ibn Barmak, is credited by the tenth-century Tunisian scholar Abdallah ibn abi-Zayd with initiating the Abbasids’ policy of importing Greek books from the Byzantine Empire.
The most important intellectual institution in Baghdad under the Abbasids was the famous Bayt al-Hikma, or House of Wisdom, which originally seems to have been basically a library. Pahlavi manuscripts were kept there and in the early Abbasid period some of these were translated into Arabic. The chronicler Ibn al-Nadim notes that the court astrologer Abu Sahl ibn Nawbaht was employed by Harun al-Rashid at the Bayt al-Hikma, where “he translated from Persian into Arabic and relied in his scholarship on the books of Iran.” During the reign of al-Ma'mun astronomers and mathematicians were associated with the Bayt al-Hikma, which at that time probably served as a research institute as well as a library. Ibn al-Nadim also reports that the famous mathematician and astronomer Muhammad ibn Musa al-Khwarizmi (fl. ca. 828) “was employed full-time in the Bayt al-Hikma in the service of al-Ma'mun.”
Al-Khwarizmi 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 circa 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. ca. 786-833), under the patronage of the vezir Yahya ibn Khalid ibn Barmak. Al-Hajjaj did an improved and abbreviated version of the Elements for al-Ma'mun, apparently for use as a school textbook.
Al-Mahdi commissioned the translation of Aristotle's Topics into Arabic from Syriac, into which it had been translated from Greek. Later the work was translated directly from Greek into Arabic. The motivation for translating the Topics was that it 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.
Harun al-Rashid's Baghdad is the setting for the Thousand Nights and One Night, where the “Tale of Aladdin and His Wonderful Lamp” reflects the marvels of the new science and the amazing inventions and discoveries that were attributed to wizard scientists. The medieval Islamic scientist was, at least in the popular view, the prototype of the villainous Moor who led Aladdin to the lamp. As Shaharzad says of the Moor: “From his earliest youth he had studied sorcery and spells, geomancy and alchemy, astrology, fumigation and enchantment; so that after thirty years of wizardry, he had learnt the existence of a powerful lamp in some unknown place, powerful enough to raise its owner above the kings and powers of the world.”
Harun al-Rashid's son al-Ma'mun continued the translation program of his predecessors. Al-Mas'udi writes of al-Ma'mun's interest in astrology and his patronage of intellectual investigations: “At the beginning of his reign … he used to spend time investigating astrological rulings and prognostications, to follow what the stars prescribed, and to model his conduct on that of the past Sassanian emperors…. He had jurists and the learned among men of general culture attend his session; he had such men brought from various cities and stipends for them allocated.”
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. ca. 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 founding of Islamic philosophy is credited to Abu Yusuf Yaqub ibn Ishaq al-Kindi (ca. 801-866), 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. His Letter on the Method of Banishing Sadness says that the cure for melancholia is applying oneself to the only enduring object, the world of the intellect.
Al-Kindi also wrote a work called The Theory of the Magic Art, or On Stellar Rays, which survives only in medieval Latin manuscripts. He begins the treatise by saying that stellar rays are emitted by celestial bodies and influence everything in the universe, mankind included, and that a study of the heavens thus allows astrologers to predict the future. He concludes with a discussion of the magical power of talismanic inscriptions, an occult art that is still practiced in Islam. “The sages,” he writes, “have proved by frequent experiments that figures and characters inscribed by the hand of man on various materials with intention and due solemnity of place and time and other circumstances have the effect of motion upon eternal objects.”
The most important figures in the program for sponsoring science under al-Ma'mun and his immediate successors were the Banu Musa, three brothers named Muhammad, Ahmad, and al-Hasan. These were the sons of Musa ibn Shakir, a former highway robber who became an astrologer in Merv, where he befriended al-Ma'mun before the latter became caliph in 813. When Musa died his three sons were adopted by al-Ma'mun, who had them educated in Baghdad after he became caliph. After finishing their studies the Banu Musa served al-Ma'mun and his immediate successors in various ways, becoming rich and powerful in the process. They spent much of their wealth in collecting ancient manuscripts, and they also supported a group of translators in Baghdad. The Banu Musa themselves are credited with writing some twenty books on astronomy, mathematics, and engineering, three of which have survived, including a treatise by Ahmad on ingenious mechanical devices patterned on the automata of Hellenistic Greece.
Ibn Khallikan also tells the story of how al-Ma'mun directed the Banu Musa to measure the circumference of the earth, to verify the measurements made by Eratosthenes and other ancient Greek scientists. The method used by the Banu Musa was to measure the north-south distance between two points in the Sinjar desert where the elevation of the polestar differed by one degree, whereupon they multiplied this by 360 to obtain the circumference of the earth. They value they obtained, according to Ibn Khallikan, was 8,000farsakhs, or 24,000 miles; the presently accepted value is 24,092 miles.
The two most famous translators of the period in Baghdad were Hunayn ibn Ishaq and Thabit ibn Qurra, both of whom were employed by the Banu Musa “for full-time translation,” according to the chronicler Abu-Sulayman al-Sigistani, who says they were paid a salary that put them on a par with the highest officials in the government bureaucracy.
Hunayn ibn Ishaq (808-73), known in Latin as Jannitus, was born at al-Hira in southern Iraq, the son of a Nestorian apothecary. He went to Baghdad to study under the Nestorian physician Yuhannah ibn Mas-awayh (d. 857), the personal physician to al Ma'mun and his successors. Hunayn, who at the time knew only Syriac, was disappointed by Ibn Masawayh, who discouraged him when he inquired about Greek medical texts. According to his autobiography, the Risala, Hunayn then went away to “the land of the Greeks”(bilal-al-Rum, probably Byzantium) and obtained a sound knowledge of Greek, after which he lived in Basra for a time to learn Arabic. 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 Dioscorides’ De Materia Medica, 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 indefatigable in his search for Greek manuscripts, as he writes in regard to Galen's De Demonstratione: “I sought for it earnestly and traveled in search of it in the lands of Syria, Palestine, and Egypt until I reached Alexandria, but I was not able to find anything except about half of it in Damascus.”
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 works 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.
One of the important translators and scientists, Thabit ibn Qurra (ca. 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 was working as a money changer in Harran when he was “discovered” by Muhammad ibn Musa, one of the Banu Musa brothers, who was returning from an expedition to find ancient Greek manuscripts in the Byzantine Empire. Muhammed brought the young Thabit back with him to Baghdad, where he became one of the salaried translators who worked for the Banu Musa along with Ishaq ibn Hunayn. After Thabit established himself, a number of his fellow Sabeans joined him in Baghdad, where they formed a school of mathematics, astronomy, and astrology that lasted through three generations.
Thabit translated works from both Syriac and Greek into Arabic, including the Introduction to Arithmetic by Nichomachus as well as improved editions of Euclid's Elements and Ptolemy's Almagest His descendants also produced Arabic translations, in particular, renderings of the writings of Archimedes and Apollonius of Perge.
Thabit wrote treatises of his own as well, including 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.
Thabit revived the erroneous “trepidation theory” of Theon of Alexandria. This held that the pole of the heavens oscillated back and forth, as opposed to the correct theory, first given by Hipparchus, that the celestial pole precessed in a circular path. Thabit pictured the planets as being embedded in solid spheres with a compressible fluid between the orbs and the eccentric circles. His planetary theory included a mathematical analysis of motion, in which he referred to the speed of a moving body at a particular point in space and time, a concept that is now part of modern kinematics. His contributions in mathematics include calculating the volume of a paraboloid and giving geometrical solutions to some quadratic and cubic equations. He also formulated a remarkable theorem concerning so-called amicable numbers, where each number of an “amicable” pair is the sum of the proper divisors (all of its factors except itself) of the other, the smallest such pair being 220 and 284.
Another prominent figure of the translation movement was Qusta ibn Luqa, a Greek-speaking Christian from the Lebanon, who worked in Baghdad as a physician, scientist, and translator until his death in 913. His translations included works by Aristarchus, Hero, and Diophantus. He wrote commentaries on Euclid's Elements and Dioscorides’ De Materia Medica, 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.
Qusta also wrote a work on magic entitled Epistle Concerning Incantations, Adjurations and Amulets, a Latin translation of which was cited by Albertus Magnus in the thirteenth century. Qusta's attitude toward sorcery is evident from an anecdote in this book, where he tells the story of “a certain great noble of our country” who believed that a witch had made him impotent. Qusta advised the noble to rub himself down with the gall of a crow mixed with sesame, persuading him that this was an aphrodisiac, and this gave the man such confidence that he overcame his imaginary ailment and regained his sexual powers.
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 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. Islamic scholars dated the beginning of this age of enlightenment to the reign of Harun al-Rashid, as in the encomium written by the poet Mosuli:
Did you not see how the sun came out of hiding on Harun's accession and flooded the world with light?