In those lusty centuries of Islamic life the Moslems labored for such an understanding. The caliphs realized the backwardness of the Arabs in science and philosophy, and the wealth of Greek culture surviving in Syria. The Umayyads wisely left unhindered the Christian, Sabaean, or Persian colleges at Alexandria, Beirut, Antioch, Harran, Nisibis, and Jund-i-Shapur; and in those schools the classics of Greek science and philosophy were preserved, often in Syriac translations. Moslems learning Syriac or Greek were intrigued by these treatises; and soon translations were made into Arabic by Nestorian Christians or Jews. Umayyad and Abbasid princes stimulated this fruitful borrowing. Al-Mansur, al-Mamun, and al-Mutawakkil dispatched messengers to Constantinople and other Hellenistic cities—sometimes to their traditional enemies the Greek emperors—asking for Greek books, especially in medicine or mathematics; in this way Euclid’s Elements came to Islam. In 830 al-Mamun established at Baghdad, at a cost of 200,000 dinars ($950,000), a “House of Wisdom” (Bayt al-Hikmah) as a scientific academy, an observatory, and a public library; here he installed a corps of translators, and paid them from the public treasury. To the work of this institution, thought Ibn Khaldun,20 Islam owed that vibrant awakening which in causes—the extension of commerce and the rediscovery of Greece—and results—the flowering of science, literature, and art—resembled the Italian Renaissance.
From 750 to 900 this fertilizing process of translation continued, from Syriac, Greek, Pahlavi, and Sanskrit. At the head of the translators in the House of Wisdom was a Nestorian physician, Hunain ibn Ishaq (809–73)—i.e., John son of Isaac. By his own account he translated a hundred treatises of Galen and the Galenic school into Syriac, and thirty-nine into Arabic; through his renderings some important works of Galen escaped destruction. Further, Hunain translated Aristotle’s Categories, Physics, and Magna Moralia;Plato’s Republic, Timaeus, and Laws; Hippocrates’ Aphorisms, Dioscorides’ Materia Medica, Ptolemy’s Quadripartitum, and the Old Testament from the Septuagint Greek. Al-Mamun endangered the treasury by paying Hunain in gold the weight of the books he had translated. Al-Mutawakkil made him court physician, but jailed him for a year when Hunain, though threatened with death, refused to concoct a poison for an enemy. His son Ishaq ibn Hunain helped him with his translations, and himself rendered into Arabic the Metaphysics, On the Soul, and On the Generation and Corruption of Animals of Aristotle, and the commentaries of Alexander of Aphrodisias—a work fated to wield great influence on Moslem philosophy.
By 850 most of the classic Greek texts in mathematics, astronomy, and medicine had been translated. It was through its Arabic version that Ptolemy’s Almagest received its name; and only Arabic versions preserved Books V–VII of the Conics of Apollonius of Perga, the Mechanics of Hero of Alexandria, and the Pneumatics of Philo of Byzantium. Strange to say, the Mohammedans, so addicted to poetry and history, ignored Greek poetry, drama, and historiography; here Islam accepted the lead of Persia instead of Greece. It was the misfortune of Islam and humanity that Plato, and even Aristotle, came into Moslem ken chiefly in Neoplatonic form: Plato in Porphyry’s interpretation, and Aristotle discolored by an apocryphal Theology of Aristotle written by a Neoplatonist of the fifth or sixth century, and translated into Arabic as a genuine product of the Stagirite. The works of Plato and Aristotle were almost completely translated, though with many inaccuracies; but as the Moslem scholars sought to reconcile Greek philosophy with the Koran, they took more readily to Neoplatonist interpretations of them than to the original books themselves. The real Aristotle reached Islam only in his logic and his science.
The continuity of science and philosophy from Egypt, India, and Babylonia through Greece and Byzantium to Eastern and Spanish Islam, and thence to northern Europe and America, is one of the brightest threads in the skein of history. Greek science, though long since enfeebled by obscurantism, misgovernment, and poverty, was still alive in Syria when the Moslems came; at the very time of the conquest Severus Sebokht, abbot of Ken-nesre on the upper Euphrates, was writing Greek treatises on astronomy, and was making the first known mention of Hindu numerals outside of India (662). The Arabic inheritance of science was overwhelmingly Greek, but Hindu influences ranked next. In 773, at al-Mansur’s behest, translations were made of the Siddhantas—Indian astronomical treatises dating as far back as 425 B.C.; these versions may have been the vehicle through which the “Arabic” numerals and the zero were brought from India into Islam.21 In 813 al-Khwarizmi used the Hindu numerals in his astronomical tables; about 825 he issued a treatise known in its Latin form as Algoritmi de numero Indorum—“al-Khwarizmi on the Numerals of the Indians”; in time algorithm or algorism came to mean any arithmetical system based on the decimal notation. In 976 Muhammad ibn Ahmad, in his Keys of the Sciences, remarked that if, in a calculation, no number appears in the place of tens, a little circle should be used “to keep the rows.”22 This circle the Moslems called sifr, “empty” whence our cipher; Latin scholars transformed sifr intozephyrum, which the Italians shortened into zero.
Algebra, which we find in the Greek Diophantes in the third century, owes its name to the Arabs, who extensively developed this detective science. The great figure here—perhaps the greatest in medieval mathematics—was Muhammad ibn Musa (780–850), called al-Khwarizmi from his birthplace Khwarizm (now Khiva), east of the Caspian Sea. Al-Khwarizmi contributed effectively to five sciences: he wrote on the Hindu numerals; compiled astronomical tables which, as revised in Moslem Spain, were for centuries standard among astronomers from Cordova to Chang-an; formulated the oldest trigonometrical tables known; collaborated with sixty-nine other scholars in drawing up for al-Mamun a geographical encyclopedia; and in his Calculation of Integration and Equationgave analytical and geometrical solutions of quadratic equations. This work, now lost in its Arabic form, was translated by Gerard of Cremona in the twelfth century, was used as a principal text in European universities until the sixteenth century, and introduced to the West the word algebra (al-jabr—“restitution,” “completion”). Thabit ibn Qurra (826–901), besides making important translations, achieved fame in astronomy and medicine, and became the greatest of Moslem geometers. Abu Abdallah al-Battani (850–929), a Sabaean of Raqqa known to Europe as Albategnus, advanced trigonometry far beyond its beginnings in Hipparchus and Ptolemy by substituting triangular for Ptolemy’s quadrilateral solutions, and the sine for Hipparchus’ chord; he formulated the trigonometrical ratios essentially as we use them today.
The Caliph al-Mamun engaged a staff of astronomers to make observations and records, to test the findings of Ptolemy, and to study the spots on the sun. Taking for granted the sphericity of the earth, they measured a terrestrial degree by simultaneously taking the position of the sun from both Palmyra and the plain of Sinjar; their measurement gave miles—half a mile more than our present calculation; and from their results they estimated the earth’s circumference to approximate 20,000 miles. These astronomers proceeded on completely scientific principles: they accepted nothing as true which was not confirmed by experience or experiment. One of them, Abu’l-Farghani, of Transoxiana, wrote (c. 860) an astronomical text which remained in authority in Europe and Western Asia for 700 years. Even more renowned was al-Battani; his astronomical observations, continued for forty one years, were remarkable for their range and accuracy; he determined many astronomical coefficients with remarkable approximation to modern calculations—the precession of the equinoxes at 54.5″ a year, and the inclination of the ecliptic at 23° 55′.23 Working under the patronage of the early Buwayhid rulers of Baghdad, Abu’l-Wafa (in the disputed opinion of Sadillot) discovered the third lunar variation 600 years before Tycho Brahe.24 Costly instruments were built for the Moslem astronomers: not only astrolabes and armillary spheres, known to the Greeks, but quadrants with a radius of thirty feet, and sextants with a radius of eighty. The astrolabe, much improved by the Moslems, reached Europe in the tenth century, and was widely used by mariners till the seventeenth. The Arabs designed and constructed it with aesthetic passion, making it at once an instrument of science and a work of art.
Even more important than the charting of the skies was the mapping of the earth, for Islam lived by tillage and trade. Suleiman al-Tajir—i.e., the merchant—about 840 carried his wares to the Far East; an anonymous author (851) wrote a narrative of Suleiman’s journey; this oldest Arabic account of China antedated Marco Polo’s Travels by 425 years. In the same century Ibn Khordadhbeh wrote a description of India, Ceylon, the East Indies, and China, apparently from direct observation; and Ibn Hauqal described India and Africa. Ahmad al-Yaqubi, of Armenia and Khurasan, wrote in 891 a Book of the Countries, giving a reliable account of Islamic provinces and cities, and of many foreign states. Muhammad al-Muqaddasi visited all the lands of Islam except Spain, suffered countless vicissitudes, and in 985 wrote his Description of the Moslem Empire—the greatest work of Arabic geography before al-Biruni’s India.
Abu al-Rayhan Muhammad ibn Ahmad al-Biruni (973–1048) shows the Moslem scholar at his best. Philosopher, historian, traveler, geographer, linguist, mathematician, astronomer, poet, and physicist—and doing major and original work in all these fields—he was at least the Leibniz,25 almost the Leonardo, of Islam. Born like al-Khwarizmi near the modern Khiva, he signalized again the leadership of the Transcaspian region in this culminating century of medieval science. The princes of Khwarizm and Tabaristan, recognizing his talents, gave him a place at their courts. Hearing of the bevy of poets and philosophers at Khwarizm, Mahmud of Ghazni asked its prince to send him al-Biruni, Ibn Sina, and other savants; the prince felt obliged to comply (1018), and al-Biruni went to live in honor and studious peace with the bellicose ravisher of India. Perhaps it was in Mahmud’s train that al-Biruni entered India; in any case he stayed there several years, and learned the language and the antiquities of the country. Returning to Mahmud’s court, he became a favorite of that incalculable despot. A visitor from northern Asia offended the king by describing a region, which he claimed to have seen, where for many months the sun never set; Mahmud was about to imprison the man for jesting with royalty when al-Biruni explained the phenomenon to the satisfaction of the king and the great relief of the visitor.26 Mahmud’s son Masud, himself an amateur scientist, showered gifts and money upon al-Biruni, who often returned them to the treasury as much exceeding his needs.
His first major work (c. 1000) was a highly technical treatise—Vestiges of the Past (Athar-ul-Baqiya)—on the calendars and religious festivals of the Persians, Syrians, Greeks, Jews, Christians, Sabaeans, Zoroastrians, and Arabs. It is an unusually impartial study, utterly devoid of religious animosities. As a Moslem al-Biruni inclined to the Shia sect, with an unobtrusive tendency to agnosticism. He retained, however, a degree of Persian patriotism, and condemned the Arabs for destroying the high civilization of the Sasanian regime.27 Otherwise his attitude was that of the objective scholar, assiduous in research, critical in the scrutiny of traditions and texts (including the Gospels), precise and conscientious in statement, frequently admitting his ignorance, and promising to pursue his inquiries till the truth should emerge. In the preface to the Vestiges he wrote like Francis Bacon: “We must clear our minds … from all causes that blind people to the truth—old custom, party spirit, personal rivalry or passion, the desire for influence.” While his host was devastating India al-Biruni spent many years studying its peoples, languages, faiths, cultures, and castes. In 1030 he published his masterpiece, History of India (Tarikh al-Hind). At the outset he sharply distinguished between hearsay and eyewitness reports, and classified the varieties of “liars” who have written history.28 He spent little space on the political history of India, but gave forty-two chapters to Hindu astronomy, and eleven to Hindu religion. He was charmed by the Bhagavad Gita. He saw the similarity between the mysticism of the Vedanta, the Sufis, the Neopythagoreans, and the Neoplatonists; he compared excerpts from Indian thinkers with like passages from Greek philosophers, and expressed his preference for the Greeks. “India,” he wrote, “has produced no Socrates; no logical method has there expelled fantasy from science.”29 Nevertheless he translated several Sanskrit works of science into Arabic, and, as if to pay a debt, rendered into Sanskrit Euclid’s Elements and Ptolemy’s Almagest.
His interest extended to nearly all the sciences. He gave the best medieval account of the Hindu numerals. He wrote treatises on the astrolabe, the planisphere, the armillary sphere; and formulated astronomical tables for Sultan Masud. He took it for granted that the earth is round, noted “the attraction of all things towards the center of the earth,” and remarked that astronomic data can be explained as well by supposing that the earth turns daily on its axis and annually around the sun, as by the reverse hypothesis.30 He speculated on the possibility that the Indus valley had been once the bottom of a sea.31 He composed an extensive lapidary, describing a great number of stones and metals from the natural, commercial, and medical points of view. He determined the specific gravity of eighteen precious stones, and laid down the principle that the specific gravity of an object corresponds to the volume of water its displaces.32 He found a method of calculating, without laborious additions, the result of the repeated doubling of a number, as in the Hindu story of the chessboard squares and the grains of sand. He contributed to geometry the solution of theorems that thereafter bore his name. He composed an encyclopedia of astronomy, a treatise on geography, and an epitome of astronomy, astrology, and mathematics. He explained the workings of natural springs and artesian wells by the hydrostatic principle of communicating vessels.33 He wrote histories of Mahmud’s reign, of Subuktigin, and of Khwarizm. Oriental historians call him “the Sheik”—as if to mean “the master of those who know.” His multifarious production in the same generation with Ibn Sina, Ibn al-Haitham, and Firdausi, marks the turn of the tenth century into the eleventh as the zenith of Islamic culture, and the climax of medieval thought.34
Chemistry as a science was almost created by the Moslems; for in this field, where the Greeks (so far as we know) were confined to industrial experience and vague hypothesis, the Saracens introduced precise observation, controlled experiment, and careful records. They invented and named the alembic (al-anbiq), chemically analyzed innumerable substances, composed lapidaries, distinguished alkalis and acids, investigated their affinities, studied and manufactured hundreds of drugs.* Alchemy, which the Moslems inherited from Egypt, contributed to chemistry by a thousand incidental discoveries, and by its method, which was the most scientific of all medieval operations. Practically all Moslem scientists believed that all metals were ultimately of the same species, and could therefore be transmuted one into another. The aim of the alchemists was to change “base” metals like iron, copper, lead, or tin into silver or gold; the “philosopher’s stone” was a substance—ever sought, never found—which when properly treated would effect this transmutation. Blood, hair, excrement, and other materials were treated with various reagents, and were subjected to calcination, sublimation, sunlight, and fire, to see if they contained this magic al-iksir or essence.36 He who should possess this elixir would be able at will to prolong his life. The most famous of the alchemists was Jabir ibn Hayyan (702–65), known to Europe as Gebir. Son of a Kufa druggist, he practiced as a physician, but spent most of his time with alembic and crucible. The hundred or more works attributed to him were produced by unknown authors, chiefly in the tenth century; many of these anonymous works were translated into Latin, and strongly stimulated the development of European chemistry. After the tenth century the science of chemistry, like other sciences, gave ground to occultism, and did not lift its head again for almost three hundred years.
The remains of Moslem biology in this period are scant. Abu Hanifa al-Dinawari (815–95) wrote a Book of Plants based on Dioscorides, but adding many plants to pharmacology. Mohammedan botanists knew how to produce new fruits by grafting; they combined the rose bush and the almond tree to generate rare and lovely flowers.37 Othman Amr al-Jahiz (d. 869) propounded a theory of evolution like al-Masudi’s: life had climbed “from mineral to plant, from plant to animal, from animal to man.”38 The mystic poet Jalal ud-din accepted the theory, and merely added that if this has been achieved in the past, then in the next stage men will become angels, and finally God.39