Islamic science developed apace with the translation movement, generated by polymath philosophers and scientists of extraordinary versatility. The founding of Islamic philosophy is credited to Abu Yusuf Yaqub ibn Ishaq al-Kindi (ca. 801–66), the Latin Alkindes, famous in the West as the ‘Philosopher of the Arabs’ – an epithet also given to him in both Arabic and Persian sources. Al-Kindi was from a wealthy Arab family in Kufa, in present-day Iraq, which he left to study in Baghdad. There he founded his own intellectual circle of patronage, translation, writing and teaching, enjoying the patronage of al-Ma’mun and his successor al-Mu’tasim. He was not a translator himself, knowing neither Greek nor Syriac, but he appears to have worked on the Arabic texts of those who did the translations, correcting, completing or commenting upon them. He was also a patron of the translation movement.
Al-Kindi benefited from the translation movement to become the first of the Islamic philosopher-scientists, forging a Neoplatonic reconciliation between Platonic and Aristotelian philosophy. Ibn al-Nadim listed 242 works by al-Kindi, including treatises in philosophy, astronomy, cosmology, mathematics, physics meteorology, optics, medicine, pharmacology, zoology, geography, meteorology, mineralogy, metallurgy, music, cryptology, politics, theology, alchemy and astrology, as well as technological writings on such topics as the making of clocks, astronomical instruments, and even of objects such as swords. Only about ten per cent of these works have survived and been edited.
Al-Kindi’s extraordinarily wide range of interests is characteristic of Islamic philosopher-scientists, as it had been for Aristotle, for they were interested in everything in creation. But not everything that al-Kindi wrote was of the highest quality, and some of it is no more than superstition typical of the times, such as the notion that the characteristics of various peoples are determined by the configuration of the celestial bodies above their homeland.
The longest of al-Kindi’s extant works is On First Philosophy, of which only the first four chapters have survived. The title is Kindi’s homage to ancient philosophies such as that of Aristotle, who referred to metaphysics as the ‘first philosophy’, which, as al-Kindi says in his introduction, is the knowledge of the causes of things: ‘Knowledge of the first cause has truthfully been called “First Philosophy”, since all the rest of philosophy is contained in its knowledge. The first cause is, therefore, the first in nobility, the first in genus, the first in rank with respect to that knowledge which is most certain; and the first in time, since it is the cause of time.’
Al-Kindi acknowledged his debt to the Greeks in the search for truth, writing that knowledge is accumulated across the centuries through the efforts of many scholars extending and perfecting the work of their predecessors. As he wrote in the preface to On First Philosophy, which he dedicated to Caliph al-Mu’tasim: ‘We should not be ashamed to acknowledge truth and to assimilate it from whatever source it comes to us, even if it is brought to us by former generations and foreign peoples. For him who seeks the truth there is nothing of higher value than truth itself; it never cheapens or abases him who searches for it, but ennobles and honours him.’
Many of al-Kindi’s ideas were influenced by Aristotle, as is evident from his treatise On the Number of Books by Aristotle and What is Needed to Learn Philosophy. But he was also influenced by the Neoplatonists Porphyry and Proclus, the Stoics, John Philoponus and other Alexandrian philosophers of the sixth century, and by the occult sciences of the Corpus Hermeticum. As he notes in the preface to On First Philosophy, he established the practice of quoting from Aristotle and other Greek writers and then commenting upon their ideas and adapting them to Islamic language: ‘My principle is first to record in complete quotations all that the Ancients have said on the subject; secondly to complete what the Ancients have not fully expressed, and this according to the usage of our Arabic language, the customs of our age and our own ability.’
The world is finite in both space and time, according to al-Kindi, who believed that it had been created out of nothing by God, in which he disagreed with the Greek rejection of creation ex nihilo. This was due to al-Kindi’s desire to reconcile Greek philosophy and Islamic theology, to create a philosophy for an Islamic community, which is evident in his work On the Number of Aristotle’s Works, where he contrasts the approach of rational philosophers with that of prophets of revealed religion: ‘The philosopher may intend to answer such questions with great effort, using his own devices, which he has at his disposal due to long perseverance in inquiry and exercise. But we will find that he does not arrive at what he seeks with anything like the brevity, clarity, unerringness, and comprehensiveness that is shown by the answer of the Prophet.’
Al-Kindi generally takes the Aristotelian view in his treatise on the Five Essences, which he identifies as matter, space, form, motion and time. In another treatise, the Nature of the Sphere is Different from That of the Four Elements, he adopts Aristotle’s model in which the four terrestrial elements – earth, water, air and fire – are arranged in concentric spheres from earth outward, and says that the celestial bodies are composed of a ‘fifth element’, or ‘quintessence’, which he does not name, but that is obviously the aether of Anaxagoras and Aristotle.
Al-Kindi’s treatise on the Definitions and Descriptions of Things follows the example of Aristotle’s Metaphysics in defining and elaborating on the technical terms used in philosophy. This contributed to the development of the vocabulary of Islamic philosophy, although many of the terms introduced by al-Kindi were changed by later Arabic writers.
Al-Kindi was the first in Islam to classify the sciences, basing his system on the classification of Aristotle’s works, beginning with the logical treatises and followed by the physical, psychological, metaphysical and ethical writings. He did not include mathematics in his system, since he considered it to be a necessary introduction to the study of philosophy rather than an integral part of the philosophical system. He emphasised this in a treatise entitled That Philosophy Cannot be Acquired Except with a Knowledge of Mathematics.
He was also an Islamic theorist of music, following in the Pythagorean tradition. His system was based on ancient Greek musical theory, where he used the letters of the alphabet to designate the notes of the scale, a notation that was adopted a century later in Europe.
Al-Kindi’s work on optics follows Theon of Alexandria in studying the propagation of light and the formation of shadows, while his theory of the emission and transmission of light is based on that of Euclid, which is based on the erroneous idea that visual images are created by rays that are transmitted by the eye to the object observed, rather than the other way round. His 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. Al-Kindi’s two treatises on optics, De aspecticus, which is a manual on ancient Greek optics, and On Burning Mirrors, were translated into Latin in the twelfth century. De aspecticus was read by Robert Grosseteste and Roger Bacon, who refers to al-Kindi’s concept of the velocity of light. The latter treatise represents an advance on what Anthemius of Tralles, one of the last two mathematical physicists of antiquity, had done in his work on the same subject.
One of al-Kindi’s extant works is on ethics, entitled On the Art of Dispelling Sorrows. This is based on the Stoic concept that happiness should not be based on the transient things of the physical world, but on the universal forms of the intellectual realm. He writes that ‘It is impossible for someone to attain everything he seeks, or to keep all of the things he loves safe from loss, because stability and permanence are nonexistent in the world of generation and corruption we inhabit. Necessarily, stability and permanence can only exist in the world of the intellect.’
Al-Kindi considered astrology to be a science, as he claims in 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 a popular custom among certain Islamic countries: ‘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.’
Aside from his contribution in bringing Aristotelian thought to some of the scholars of Baghdad, al-Kindi never established a school of philosophy. Some of al-Kindi’s treatises were translated into Latin in the twelfth century, by Gerard of Cremona and Avendauth. He is referred to by Albertus Magnus and Giles of Rome, who in his De erroribus philosophorum points out al-Kindi’s ‘errors’, particularly in cosmology and astrology.
Al-Kindi seems to have been a particularly difficult character, at least according to his contemporary al-Jahiz, who satirises him in his Book of Misers. As al-Jahiz tells the story, al-Kindi, despite his wealth, rented out rooms in his house to lodgers. One of his tenants, who headed a family of six and paid 30 dirhams a month for rent, wrote to al-Kindi and asked if two relatives could stay with him for a month. Al-Kindi called the man in and subjected him to a tongue lashing, demanding an extra 10 dirhams for the two additional lodgers, and at the same time lecturing him on the problems that landlords had to put up with from the devious ways of their tenants.
Al-Jahir (781–869) himself was an exceptionally interesting figure. He was from a very poor black family of East African origin who had moved to Basra, where as a boy he supported himself selling fish along one of the canals. He educated himself by listening to the scholars who lectured at the mosques and other gathering-places in Basra, before moving to Baghdad, where he became a highly popular writer and acquired a series of wealthy and powerful patrons. He is credited with more than two hundred works, including treatises on philosophy, zoology, psychology, history, theology, kalam, lexicography, rhetoric, and Arabic grammar, of which thirty survive. Aside from the Book of Misers, his best known work is Kitab al-Hayawan (Book of Animals), an encyclopedia in seven volumes, with descriptions and anecdotes of more than 350 types of animals, its original ideas including basic notions of natural selection through the survival of the fittest, the influence of the environment, and the notion of the interdependence of creatures through their food chain, of which he gives the following example:
The mosquitoes go out to look for their food as they know instinctively that blood is the thing which makes them live. As soon as they see the elephant, hippopotamus or any other animal, they know that the skin has been fashioned to serve them as food; and falling on it, they pierce it with their proboscises, certain that their thrusts are piercing deep enough and are capable of reaching down to draw the blood. Flies in their turn, although they feed on many and various things, principally hunt the mosquito... All animals, in short, cannot exist without food, neither can the hunted animal in turn escape being hunted in his turn.
Medicine was another branch of science highly esteemed in Islam, as is evident in one of the hadith, or sayings, attributed to the Prophet Muhammed: ‘The best gift from Allah is good health. Everyone should reach that goal by preserving it for now and the future.’
An early and great writer on Islamic medicine is Abu Bakr Muhammed ibn Zakariya al-Razi (ca. 854–ca. 930), the Latin Rhazes, who was born in Rayy, in a suburb of present-day Tehran. As a youth he is said to have played the lute before he began his studies in medicine and philosophy. According to Ibn Khallikan’s biography of al-Razi: ‘In his youth he played on the lute and cultivated vocal music, but, on reaching the age of manhood, he renounced these occupations, saying that music proceeding from between mustachios and a beard had no charm for him.’
Al-Razi learned medicine in Rayy and became the director of the hospital there before the age of thirty-two. Later he headed the hospital in Baghdad, where students came from afar to study with him. He is credited with 232 works, including treatises on virtually every aspect of medicine as well as works in philosophy, logic, mathematics, astronomy, cosmology, alchemy, theology and grammar, of which most are lost.
The most important of al-Razi’s surviving medical works is al-Hawi, known in its Latin translation as Continens, the longest extant Arabic work on medicine, filling some twenty-five volumes. It was translated into Latin under the patronage of King Charles I of Anjou by the Jewish physician Faraj ibn Salim (‘Farragut’), who completed it in 1279, after having spent most of his life in the task. His translation was printed five times between 1488 and 1542.
Al-Razi’s 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. He was famous as a physician in both the East, where he was called ‘the unsurpassed physician of Islam’, and the West, where he was known as ‘the Second Galen’.
Al-Razi’s medical writings are characterised by his greater emphasis on observational diagnosis and therapy than on the theory of illnesses and their cures. Theories of illnesses and the scholarship surrounding them are constantly evolving, but in the most basic terms, they concern the ideas that people have to explain why they become ill or remain healthy. Whenever he writes about a particular malady he summarises all that he has read on the subject in Greek and Indian sources in Arabic translation as well as in the works of earlier Islamic physicians, adding his own opinion, an approach that he also took in his philosophical treatises. The titles of some of his works reveal his sense of humour concerning the limitations and misuse of the medical profession, such as his treatises On the Fact that even Skillful Physicians Cannot Heal all Diseases, Why People Prefer Quacks and Charlatans to Skilled Physicians, On Why Some People Leave a Physician if he is Intelligent and Why Ignorant Physicians, Common Folk, and Women in the Cities are more Successful than Scientists in Treating Certain Diseases – and the Physician’s Excuse for This.
Al-Biruni’s biography of al-Razi credits him with eighty works on philosophy, of which only a few short treatises and fragments survive. Al-Razi’s extant philosophical writings show that he differed with Aristotle’s rejection of the void as well as in the doctrine of natural motion, holding instead that all bodies tend to move toward the centre of the earth. Al-Razi followed Democritus in saying that matter consisted of atoms separated by a void, their relative separation determining their primary qualities such as density. He believed in the Pythagorean doctrine of metempsychosis, or the transmigration of souls. He followed Plato’s Timaeus in holding that the five eternal principles are matter, space, time, the soul and the demiurge, or creator, known in Arabic as bari. Al-Razi’s belief in the eternity of the soul and its eventual freedom from the body ran counter to the Islamic doctrines, as did his rejection of revelation and prophecy. The latter belief caused him to be branded a heretic and infidel by many of his successors.
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.
Unlike Plato and the Islamic philosophers who followed him, al-Razi did not believe that only the elite few are capable of understanding philosophy, which he said was accessible to all humans as a way of life and was their only means of salvation.
Al-Razi’s most famous work is the Kitab al-Tibb al-Ruhani, known in its English translation as the Book of Spiritual Physick. This is a treatise on ethics based on Plato’s concept of the Soul from the Republic, and was a companion volume to the Kitab al-Mansuri, known in its Latin translation as the Liber Almansoris, named for Abu Salih al-Mansur, prince of Kirman and Khorasan, which dealt with the ‘Bodily Physick’.
The Spiritual Physick is divided into twenty chapters, whose headings reveal the character of the book: Of the Excellence and Praise of Reason; Of Suppressing the Passion, with a Summary of the Views of Plato the Philosopher; Summary Prolegomena to the Detailed Account of the Evil Dispositions of the Soul; Of How a Man may Discover his Own Vices; Of Repelling Carnal Love and Familiarity, with a Summary Account of Pleasure; Of Repelling Conceit; Of Repelling Envy; Of Repelling Excessive and Hurtful Anger; Of Casting Away Mendacity; Of Casting Away Miserliness; Of Repelling Excessive and Hurtful Anxiety and Worry; Of Dismissing Grief; Of Repelling Greed; Of Repelling Habitual Drunkenness; Of Repelling Addiction to Sexual Intercourse; Of Repelling Excessive Fondness, Trifling, and Ritual; Of the Amount of Earning, Acquiring, and Expending; Of Repelling the Strife and Struggle in Quest of Worldly Rank and Station, and the Difference between the Counsel of Passion and Reason; Of the Virtuous Life; Of the Fear of Death. In the chapter on drunkenness, al-Razi addresses a poem to those addicted to 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 describes his own moderate lifestyle in The Philosophical Way of Life, where he says that so far as indulgence and self-denial are concerned ‘I have never gone beyond the upper and lower limits I have defined’, noting that he had always devoted himself to scholarship. A contemporary describes al-Razi’s routine in his last years, when he continued to practice as a physician despite his failing sight.
He used to sit in his reception room with his students around him, surrounded by their students, and then still other students. A patient would enter and describe his symptoms to the first one he met. If they did not know what was wrong, he would progress to the next group. If they did not know, al-Razi himself would discuss the case. He was generous, dignified and honest with the people – so compassionate with the poor and sick that he would supply ample food for them and provide them with nursing care...He was never seen to be taking notes or transcribing information, and I never went in to see him without finding him writing out a draft or a revision...He went blind at the end of his life.
Al-Razi’s failing sight was apparently caused by a cataract that developed in his later years. He refused surgery to have the cataract removed, saying that he had seen enough of the world. A poem that he wrote in his last days reveals the spirit in which he faced death:
The next great Islamic philosopher-scientist after al-Kindi and al-Razi was Abu Nasr Muhammed al-Farabi (ca. 870–950). Al-Farabi, known in Latin as Alpharabius, was probably of Turkish origin, born at Farab in Transoxania, the region beyond the Oxus River (the modern Syr Darya) in Central Asia. He took courses in law and music at Bukhara then went to Merv, where he studied logic under a Syriac-speaking Nestorian scholar named Yuhanna ibn Haylan, whom he accompanied to Baghdad during the reign of Caliph al-Mu’tadid (r. 892–902). During the caliphate of al-Muktafi (r. 902–8) he moved to Harran with Ibn Haylan, where according to his own account, quoted by al-Khattabi, he completed his study of Aristotle’s Posterior Analytics. ‘After this,’ according to al-Khattabi, ‘he travelled to the land of the Greeks and stayed in their land for eight years until he completed [the study of the] science[s] and learned the entire philosophic syllabus.’ His Greek studies would have been done at the university in Constantinople, where the study of ancient Greek philosophy had been revived during the patriarchate of Photius (r. 858–67, 877–86). This was part of a cultural revival in Byzantium that coincided with the flowering of Islamic knowledge and culture under the early ‘Abassid caliphs.
Al-Farabi returned to Baghdad ca. 910 and remained there until 942, teaching and writing. He then moved to the court of the Hamdanid prince Sayf al-Dawlah in Damascus and Aleppo. He is credited with more than one hundred works, of which 33 have survived, including 12 in philosophy, 4 each in mathematics and music, 3 each in astronomy, physics and literature, 2 in medicine, and 1 each in chemistry and zoology.
He was deeply influenced by both Plato and Aristotle, and made an effort to reconcile Platonic and Aristotelian ideas when they conflicted. His goal was to revive the Aristotelianism taught at Alexandria in late antiquity, which had been transmitted to Islam by a succession of teachers, one of the last of whom may have been his own mentor Yuhanna ibn Haylan. Al-Farabi writes of this in his Appearance of Philosophy, where he says that the teaching of some of Aristotle’s logical works was suppressed by the Christian bishops of Alexandria, and that thenceforth those works could only be taught privately until the coming of Islam.
Al-Farabi sought to give philosophy precedence over law, using Greek thought to reinterpret Islamic culture. His writings can be divided into three categories: introductory works on philosophy, commentaries on and paraphrases of Aristotle, and his own original theses.
The first category comprises mostly introductions to the ideas of Plato and Aristotle. The introductory works include the Book of Indication of the Way to Happiness; Book on Attaining Happiness; Philosophy of Plato, its Parts and the Order of these Parts; Philosophy of Aristotle; Book of Common Views of Two Philosophers, Divine Plato and Aristotle; Directing Attention to the Way of Happiness; Terms Used in Logic; and Paraphrase of the ‘Categories’.
This first category of the works of al-Farabi also includes a general thesis called The Ennumeration of the Sciences, known in one of its Latin translation by Gerard of Cremona as De Scientiis. Al-Farabi’s system for classifying the sciences was modified and elaborated upon by the Arabic scholars who succeeded him. The main branches of the sciences in his system are the Science of Language; the Science of Logic; the Mathematical Sciences; Physics and Metaphysics, Divine Science; and political philosophy, Jurisprudence, and Theology. The principal branches are further subdivided, so that the Mathematical Sciences are listed as Arithmetic, Geometry, Optics, Astronomy, Music, Science of Weights, and Mechanical Artifices. Al-Farabi, in his introduction, points out the advantages to be gained in studying his book: ‘The book can be of use to the educated layman who wants to gain an overall impression of all the sciences, as well as for people who wish to be taken as scholars.’
Al-Farabi attacked astrology in his Ennumeration of the Sciences. Despite his opposition to astrology, al-Farabi still includes it with observational and mathematical astronomy as part of the ‘Science of the Heavens’.
The second category of al-Farabi’s writings includes commentaries on and paraphrases of Aristotle’s Nicomachean Ethics and the whole of the Organon, his logical works, namely Categoriae (Categories), De Interpretatione (On Interpretation), Analytica Priora (Prior Analytics), Analytica Posteriora (Posterior Analytics), Topica (Topics) and De Sophististicis Elenchis (On Sophistical Refutations). His commentary on the Nicomachean Ethics puts forward his views on the necessity of guidance and education: ‘Some men need little guidance, others a great deal of it. In addition, even when a man is guided...he will not, in the absence of external stimulus and something to rouse him, necessarily do what he had been taught and guided to do. This is how most men are. Therefore they need someone to make all this known to them and rouse them to do it.’
The third category comprises al-Farabi’s original philosophical works, the best known of which is The Principles of the Opinions of the People of the Excellent Virtuous City. Here, following the example of Plato’s Republic, al-Farabi examines the metaphysical basis of the ideal Islamic state. Using Aristotle’s world-picture as his model, he develops an hierarchical cosmology based on six principles, namely the First Cause, the Secondary Causes, the Active Intellect, Soul, Form and Matter. The First Cause is associated with the outermost sphere of the heavens; the Secondary Causes are incorporeal Intellects embodied in the nested spherical shells of the stars, the sun, the moon and the five planets; while the Active Intellect controls the terrestrial world, composed of earth, water, air and fire, which in various combinations form humans, animals and inanimate objects.
Al-Farabi’s writings include commentaries on Euclid’s Elements and Ptolemy’s Almagest, as well as an Article on Vacuum, a Treatise on the Necessity of the Art of Chemistry, a Book of Spiritual Clever Tricks and Mysteries of Nature on the Subtlety of Geometric Figures, a Book of High Reasoning on Elements of the Science of Physics, a treatise On Objections to Galen with Regard to His Discrepancy with Aristotle about Organs of the Human Body and a treatise On Rhetoric and Poetry.
Al-Farabi also wrote several treatises on musicology, the most important of which is The Great Book of Music. The theoretical part of the book, which is based mostly on Greek musicology, begins with a discussion of the physics of sound, where al-Farabi for the most part follows Aristotle. The rest of the book is devoted to musical practice concerning the various types of instruments used in the Islamic world, particularly the lute, which al-Farabi apparently played to perfection. 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.
Ibn Khallikan tells an interesting story of al-Farabi’s last days in Damascus at the court of Sayf al-Dawlah, who one evening asked him if he would like to hear some music. Al-Farabi said that he would, and a number of musicians in turn were brought in to play for him, but he found fault with each of them. Sayf al-Dawlah then said to him, ‘Have you any proficiency in this art?’, and al-Farabi answered ‘Yes’, whereupon he prepared to play before the prince and his companions. Ibn Khallikan then goes on to tell of al-Farabi’s enchanting performance:
He then drew from his waist a leather bag, opened and drew from it some reeds, which he put together. Then he played on them, whereupon all who were at the majlis [assembly] laughed. Then he took them to pieces and put them together another way, and when he played on them everyone in the majlis cried. Then he took them to pieces [yet] again, put them together differently, played on them and everyone in the majlis, even the doorkeeper, fell asleep. And al-Farabi went out.