The Islamic renaissance began even before the translation movement ended, spreading eastward to central Asia and westward into North Africa and Spain, giving rise to works in all of the branches of science known to the ancient Greeks. The preponderance of the earliest figures in this renaissance worked in the region between Baghdad and central Asia, where Arabic science would continue to flourish long after it had declined elsewhere in the Islamic world, particularly in astronomy.
The rapid expansion of early Islam, together with the requirement that all Muslims make a pilgrimage to Mecca, stimulated an interest in geography and natural history among Arabic scholars. The most popular of the early Islamic works in this area were by Abu'l Hasan al-Masudi, who has been called the Muslim Pliny.
Al-Masudi was born toward the end of the ninth century near Baghdad, where he studied before traveling throughout Asia and parts of Europe, reporting that he found the Europeans “humorless, gross and dull.” He spent the last decade of his life in Syria and Egypt, where he died in 956. His best-known work is Prairies of Gold, which reveals him as a traveler, chronicler, geographer, geologist, and natural historian. Al-Masudi's last work was his Book of Indications and Revisions, which summarizes his observations and philosophy concerning nature and history. He also developed theories of music and advocated musical therapy, as well as proposing the concept of human evolution. He cautioned against an uncritical acceptance of the “ancients,” believing that science advanced through new discoveries.
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. Muhammad ibn Jabir al-Battani (858-929) begins his Zij al-Sabi by citing a verse of the Koran 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 Stellanon (On the Science of Stars), was used in Europe until 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. His observations of the changing position of the celestial pole led him to reject the trepidation theory of Thabit ibn Qurra in favor of the ancient precession theory of Hipparchus. Ptolemy had measured the rate of precession to be 1 degree in 100 years, while al-Battani found it to be 1 degree in 66 years; the correct value is 1 degree in 72 years. Al-Battani's astronomical writings were translated into Latin and were used by astronomers until the seventeenth century.
Many Arabic astronomers doubled as astrologers, given the great popularity of astrology among all classes in the Islamic world. This was despite the determined opposition of theologians, who quoted the Koran in reminding the faithful that “none in the heavens and the earth knows the unseen save Allah.” The poet Sa'di of Shiraz tells an anecdote in ridiculing the claims that astrology can predict the future. It seems that an astrologer returned home one day and found his wife with another man; when he raised a fuss about this a neighbor mocked him by saying, “What can you know of the celestial sphere when you cannot tell who is in your own house?”
Prominent Arabic philosophers also attacked astrology, the earliest to do so being Abu Nasr al-Farabi (ca. 870-950). Al-Farabi, known in Latin as Alpharabius, was a Turk born in Transoxiana, the region beyond the Oxus River (the modern Amu Darya) in central Asia, where he spent the first half of his life. He later went to school in Baghdad, where he studied logic under a Syriac-speaking Nestorian scholar named Yuhanna ibn Haylan. After two decades in Baghdad he moved to the court of Saif al-Daulah in Damascus; he lived there for the rest of his days.
Al-Farabi's attack on astrology comes in the introduction to his Enumeration of the Sciences, known in its Latin translation as De Scientiis This is the earliest extant medieval classification of the sciences, a system modified and elaborated upon by the Arabic scholars who succeeded him. Despite his opposition to astrology, al-Farabi still includes it with observational and mathematical astronomy as part of the “Science of the Heavens.”
Al-Farabi was the second Islamic Aristotelian philosopher-scientist after al-Kindi. But he was also deeply influenced by Plato and made an effort to reconcile Platonic and Aristotelian ideas when they conflicted. His treatise Al-Madina al-Fadila (The Good City) attempts to show the relation between Plato's ideal community in the Republic and Islam's sharia, or sacred law. He is noted as the Islamic founder of political philosophy and logic. His scientific works include commentaries on Euclid's Elements and Ptolemy'sAlmagest Al-Farabi's treatise on music is the earliest Islamic study of the subject, far ahead of any work in Latin Europe. He was also a composer, and some of his works were played in the rites of the Sufi brotherhoods, a number of them surviving today in the dervish orders of Turkey.
Medicine was another branch of science highly esteemed in Islam, as is evident in one of the hadith, or sayings, attributed to the Prophet Muhammad: “The best gift from Allah is good health. Everyone should reach that goal by preserving it for now and the future.”
The first great writer in Islamic medicine is Abu Bakr Muhammad ibn Zakariya al-Razi (ca. 854-ca. 930), the Latin Rhazes, who was born in the Persian city of Rayy. He was famous as a physician in both the East and the West, where he was known as “the Arabic Galen.” He studied in Rayy and became the director of the hospital there. He later headed the hospital in Baghdad, and 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. Al-Razi's writings are characterized by his greater emphasis on observational diagnosis and therapy than on a theory of illnesses and their cures. The titles of some of his works indicate that he was aware of the limitations and misuses of the medical profession, such as his treatises On the Fact That Even Skillful Physicians Cannot Heal All Diseases and Why People Prefer Quacks and Charlatans to Skilled Physicians
One of al-Razi's books, known in its English translation as Spiritual Physick, concerns the diagnosis and treatment of ailments involving both the body and the soul. Each of the chapters in the book concerns one of twenty psychosomatic diseases; he ends the fourteenth chapter, “On Drunkenness,” by quoting an Arabic poem on the evils of drink:
When shall it be within thy power
To grasp the good things God doth shower
Though they be but a span from thee,
If all thy nights in revelry
Be passed, and in the morn thy rise
With fumes of drinking in thine eyes
And heavy with its wind, ere noon
Return to thy drunkard's boon?
Al-Razi's alchemical writings are also well known, particularly the Book of Secrets Here he is less interested in the esoteric philosophical background of alchemy than in the chemical substances, processes, and laboratory equipment involved. Among the substances that he studied was naft, or petroleum, which in modern times was to become the principal source of wealth of a number of Islamic countries in the Middle East. He also worked with oil lamps, or nafata, for which he used both vegetable oils and refined petroleum as fuel.
Al-Razi wrote on magic and astrology as well as on alchemy, and his work in these fields influenced the first natural philosophers in western Europe. One of his works, entitled Of Exorcism, Fascinations, and Incantations, discusses the use of those occult practices in causing and curing diseases. Those who followed al-Razi's lead searched for the elixir of life, the philosopher's stone, talismans, and the magical properties of plants and minerals with their supposed ability to cure diseases.
The most outstanding Islamic physician in the generation after al-Razi was Ali ibn al-Abbas al-Majusi (ca. 925-994), the Latin Haly Abbas. Majusi means “Zoroastrian,” although he himself was a Muslim, born near Shiraz. His principal work is Kitab al-Maliki(The Royal Book), known in its Latin translation as Liber Regius The main interest of this book today is al-Majusi's assessment of his Greek and Arabic predecessors, including al-Razi.
Al-Majusi emphasized the importance of psychotherapy in treating psychosomatic illnesses; one of those he recognized was unrequited love. His writings on poisons, including their symptoms and antidotes, represents the beginning of medieval toxicology. He wrote on the use of opiates and problems of drug addiction as part of his general discussion of medicines, and he also emphasized chemotherapy. He opposed contraception and the use of drugs to cause abortion, except in cases where the physical or mental health of the woman was endangered. He insisted on the highest standards of medical ethics, referring his colleagues to the Hippocratic code.
The Persian astronomer Abd al-Rahman al-Sufi (903-86) was known in the West as Azophi. Little is known of his life and career except his association with the Buyid dynasts, who captured Baghdad in 945 and for more than a century afterward acted as protectors of the Abbasid caliphs, who were reduced to the role of mere puppets. Al-Sufi is best known for his Treatise on the Constellations of the Fixed Stars, a critical revision of Ptolemy's star catalog based on his own observations, which was a classic of Arabic astronomy for many centuries and later became known to the West through a Castilian translation. The old Arabic star names that he used were adopted by most later Islamic astronomers and have made their way into modern stellar terminology. The illuminated manuscripts of the Treatise are among the most beautiful in Islamic science. The paintings show forty-eight constellations, with tables giving the positions, magnitudes, and colors of all of the stars. Each of the constellations is shown in two facing views: as it would look to an observer on earth, and as it would appear on the celestial sphere to a viewer outside. The mythological figures are portrayed in Islamic rather than Greek costumes, so that in the constellation that bears his name Perseus is dressed in a flowing Arabic robe, brandishing his sword in one hand and with the other holding the severed head of Medusa by her long hair.
Some of the most renowned figures of the Islamic renaissance were polymaths who wrote on many different branches of science, including astronomy and not always excluding astrology.
Abu Rayhan al-Biruni (973-1050) is credited with 146 works, comprising treatises on astronomy, astrology, chronology, time measurement, geography, geodesy, cartography, mathematics (including arithmetic, geometry, and trigonometry), mechanics, medicine, pharmacology, meteorology, mineralogy (including gems), history, philosophy, religion, literature, and magic, as well detailed descriptions of his observational instruments and inventions. Probably of Turkish origin, he was born in the central Asian region known as Khwarazm (now in Uzbekistan) and studied under the astronomer and mathematician Abu Nasr Mansur. Later he entered the service of Sultan Mahmud al-Ghaznami of Ghazna (in what is now Afghanistan) in his campaigns of conquest in central Asia and India.
The constellation Perseus shown in al-Sufi's Treatise on the Constellations of the Fixed Stars, from a tenth-century Arabic manuscript.
The knowledge that al-Biruni obtained in these campaigns enabled him to write his major work, The Description of India, a mine of information on history, geography, science, religion, and studies of humankind and society. This work was also very influential in introducing Hindu mathematics to the Islamic world, which later passed this knowledge on to Europe. His Chronology of Ancient Nations describes the calendars and religious festivals of various peoples in antiquity. His Canon of Al-Mas'ud became the basic text of Islamic astronomy, just as his Elements of Astrology was the standard work in that field. Nevertheless, al-Biruni emphasized that he did not really believe in astrology, for he thought that the “decrees of the stars” had no place in the exact sciences.
Al-Biruni's other accomplishments include an accurate measurement of the earth's circumference; a geared calendar showing the motion of the sun and moon among the signs of the zodiac; a device for making accurate measurements of the specific gravities of liquids; a mechanical triangulation instrument for measuring distances such as the width of a river or the height of a minaret; a mathematical method for determining the qibla, the direction of Mecca from any point; a speculation on the rotation of the earth; and observations on technological processes such as the casting of iron, the production of steel, and the mining and purification of gold, all of the latter techniques and many others described in his Kitab al-Jamahir But al-Biruni's works were never translated into Latin, and so he had little influence on the subsequent development of science in Europe.
Al-Biruni's speculations about celestial motion are extremely interesting, for he disagrees with Aristotle's doctrine of natural place and natural motion, proposing instead that the heavenly bodies do have gravity (i.e., weight) despite the fact that they move in circular orbits rather than toward the center. His thoughts on celestial motion and other matters appear in his correspondence with Abu ‘Ali al-Husain ibn Sina, the Latin Avicenna, to whom he addressed a number of questions, the first of which concerns “the possible gravity of the heavens, their circular motion and the denial of the natural place of things.”
Ibn Sina (980-1037) was born and educated near Bukhara (in present-day Uzbekistan); he later lived in the Persian towns of Rayy and Hamadan, where he died. He is credited with some 270 works, including an autobiography, completed by his disciple al-Juzjani. His best known works are the Canon of Medicine and the Book of Healing, which in addition 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; he recognized the connection between emotional and physical states, including, like al-Majusi, 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 a new European science was being created from Greco-Arabic sources.
Ibn Sina's most influential follower was Sayyid Zayn al-Din Ismail al-Juzjani (d. ca. 1070), who lived in the central Asian region of Khwarazm. His principal work is the Treasury Dedicated to the King of Khwarazm, a medical encyclopedia based on Ibn Sina'sCanon, written in Persian, which established the scientific terminology for medicine, including pharmacology. Al-Juzjani's other writings include his Medical Memoranda and The Aims of Medicine, which, along with his Treasury, were the principal sources for the perpetuation of the medical teachings of Ibn Sina and his predecessors. He also wrote a treatise on astronomy, The Composition of the Heavenly Spheres, in which he dealt with Ptolemy's controversial concept of the equant, the point about which the planets move with constant velocity, as explained in the Almagest, an idea that many Islamic astronomers rejected.
The most illustrious figure in the history of Islamic mathematics is Abu'l Fath Umar ibn Ibrahim al-Khayyami (ca. 1048-ca. 1130), known in the West as Omar Khayyam, the “Tentmaker.” Khayyam was born in Nishapur, in Persia, shortly before the Seljuk Turks conquered much of the former Abbasid empire, climaxed by their capture of Baghdad in 1055.
Khayyam's principal work in mathematics is his Algebra, which is generally considered to be the culmination of Islamic research in this field, going beyond that of al-Khwarizmi to include cubic equations. He used both arithmetic and geometric methods to solve quadratic equations and employed a scheme of intersecting conics to solve cubic equations, an approach first taken by Archimedes. He was also the first to see the equivalence between algebra and geometry, finally established by Descartes in the seventeenth century.
Khayyam did research in physics and invented a water balance that was for a long time known by his name. He was also involved in a program of calendar reform initiated by the Seljuk sultan Melikshah (r. 1072-92). The Jalali calendar that he and his colleagues created is still used in Iran and other parts of the Islamic world. He refers to this work in one of the quatrains of his Rubaiyat, the volume of poetry that made him far more famous in the West than his mathematics.
Ah, but my Computations, People say
Reduced the y ear to better reckoning? Nay
‘Twas only striking from the Calendar
Unborn Tomorrow and dead Yesterday
Islamic theology reached its peak with Abu Hamid al-Ghazali (1058-1111), the Latin Algazel. The most important of al-Ghazali's works is The Incoherence of the Philosophers, an attack on the rationalism of Neoplatonist and Aristotelian physics and metaphysics, in which he criticized some of the views of Ibn Sina and al-Farabi. His writings greatly increased the popularity of mysticism in Islam, leading to a rejection of rational philosophy and science. The decline of Arabic science that began in the twelfth century is sometimes attributed partly to the influence of al-Ghazali, Nevertheless, Arabic work in mechanics and astronomy, at least, remained at a high level after his time, particularly in central Asia.
The Archimedean tradition in mechanics and hydrostatics continued to develop in late medieval Islam as far afield as central Asia. This is evidenced by the writings of Abd al-Rahman al-Khazini, who in the first half of the twelfth century flourished in Merv, in what is now Turkmenistan. Originally a slave boy of Byzantine origin, possibly a castrato, he seems to have been a high government official under Sanjar ibn Malikshah, who was first emir of Khorasan (r. 1097-1118) and then sultan of the Seljuk Empire (r. 1118-57), during which time Merv became a center of literary and scientific activity.
Al-Khazini's best known work is The Book of the Balance of Wisdom, an encyclopedia of medieval mechanics and hydrostatics that also features commentaries on the writings of earlier scholars in this field going back as far as Euclid and Archimedes. The topics covered in the encyclopedia include theories of the center of gravity; measurements of specific gravities of fifty substances, both liquid and solid; determination of the constituents of alloys; and the mechanisms of the steelyard and other balances, including the water balance of Omar Khayyam and one attributed to Archimedes. The encyclopedia also establishes standards of measurement, discusses capillary action, and describes ingenious mechanical automata The most interesting feature of this work is that al-Khazini treats gravitation as a universal force attracting all terrestrial (though not celestial) bodies toward the center of the earth, the attraction being proportional to the weight of the body. He was aware that even air has weight, and that its density decreases with height.
Al-Khazini was also a distinguished astronomer. His most important work in this field was the Sanjar Zij, the astronomical tables he compiled for Sultan Sanjar ibn Malikshah, which also includes interesting information on various calendars as well as lists of religious holidays, fasts, rulers, and prophets, concluding with tables of astrological quantities. Another of his writings on astronomy is the Treatise on Instruments Each of the seven parts of this work is devoted to an astronomical instrument, with instructions for its use as well as explanations of its geometrical basis.
Another Greek scientific tradition that flourished in late medieval Islam was the making of automata Islamic work in this field culminated with the inventions of Badi al-Zaman Abu'l Izz Ismail ibn al-Razzaz al-Jazari (fl. ca. 1200), following in the tradition of Ctesibius, Hero of Alexandria, and Philo of Byzantium.
All that is known of al-Jazari's life is contained in the introduction to his only extant work, the Book of Knowledge of Ingenious Mechanical Devices, which became the definitive text on mechanics and automata in the Islamic world. There he says that when he wrote the book he was in the service of Nasr al-Din, the ruler of the Turcoman Artukid emirate that had its capital at Diyarbakir in southeastern Anatolia.
A water-raising machine, from a fourteenth-century Arabic manuscript of al-Jazari's Book of Knowledge of Ingenious Mechanical Devices.
Some of al-Jazari's inventions later reappeared in the West, including his conical valve, mentioned by Leonardo da Vinci. He was renowned for his inventions, some of which had an obvious use, such as pumps and water-raising devices. Others were for decoration or entertainment, including fountains, musical automata, and water clocks, while a number were trick vessels of various kinds, all illustrated in miniature paintings.
The Abbasid dynasty came to an end in 1258 with the sack of Baghdad by the Mongols under Hulagu Khan, a grandson of Genghis Khan's. Hulagu had the last Abbasid caliph executed, along with a large part of the population of Baghdad. Whole quarters of the city were looted and destroyed, including the Great Mosque and the Shiite mosque of Khazi-man, and chroniclers report that piles of manuscripts were burned, including many that would have come from the House of Wisdom in Baghdad.
Baghdad was never again to be the capital of Islam. It survived only as a provincial city, at the mercy of the successive conquerors who passed that way, until it fell to Tamerlane in 1393. Thenceforth Islamic scholars could only look back on the past glories of the Abbasid capital, as in the encomium the tenth-century geographer Muqaddasi wrote of the city of Harun al-Rashid, referring to “Baghdad, which has no equal in the Orient or in the Western world.”