A thousand years ago western civilisation stood at a low ebb, with much knowledge lying neglected in the libraries of remote monasteries or in Arab archives. Anthony Kenny charts the resurgence in learning during the Middle Ages, which saw the foundation of the first universities.
The 10th century, the last of the old millennium, was, from an intellectual point of view, the darkest in the history of western Christendom.
In the six centuries before the birth of Christ, Greek scientists had made great progress in mathematics, biology, geography and astronomy. The two greatest thinkers of Greece, Plato and Aristotle, possessed philosophical genius of a grandeur never since surpassed.
But, in the centuries after the Roman Empire turned Christian, much that the pagan world had learnt was forgotten, preserved only in unconsulted manuscripts in remote monastic libraries. At the beginning of the second millennium the inhabitants of Europe knew much less about the world than their predecessors had known ten centuries previously.
In the year 1000, the one person in the world who had a real grasp of the scientific achievement of the Greeks was not a European but a Persian Muslim, Ibn Sina or Avicenna. Born in 980, he mastered in his teens the texts of Greek authors which, in Arabic translation, had been treasured in Baghdad since the era of the Arabian Nights. At the age of 20 he published an encyclopedia of logic, mathematics, physics, medicine and metaphysics.
A famous physician in later life, as well as a voluminous writer in Persian and Arabic, he assembled Greek and Arabic clinical material with some original observations of his own into a Canon of Medicine, which was to be used by practitioners in Europe until the 17th century. From him, doctors learnt the theory of the four humours, or bodily fluids (blood, phlegm, choler and black bile), which were supposed to determine people's health and character, making them sanguine, phlegmatic, choleric or melancholic as the case might be. More usefully, he identified anthrax and promoted the practice of uroscopy.
For the first two centuries of the millennium Western Europe was, intellectually, heavily dependent on Muslim culture and it was largely through the Arabs that it recovered the lost knowledge of the Greeks. The pope in the year 1000, Silvester II, was a remarkable scholar, a mathematician skilled in the use of the abacus, a musician who could play the newly improved organ, and an astronomer familiar with the terrestrial and celestial globes. He had studied in Spain, which, ruled largely by the Moors between 850 and 1150, was a principal channel by which Arabic learning reached the West, and he was an object of suspicion to some Catholics, who regarded his learning as magical and attributed it to a pact with the devil. Silvester was, however, a good teacher, and one of his pupils, as bishop of Chartres, set the fashion of founding cathedral schools, which, with monastic schools, were the principal vehicles of education in the early centuries of the millennium. There were as yet no universities.
The two great western thinkers in this pre-university era were Anselm and Abelard. Anselm, archbishop of Canterbury at the end of the 11th century, was a product of a Benedictine abbey in Normandy. He wrote on grammar, logic and theology, and is best known for his ingenious philosophical proof of the existence of God. By "God" we surely mean something than which nothing greater can be imagined; but if God was only a fiction we would be able to imagine something greater than him, namely, a God who really existed; so God is no mere fiction but really exists.
Abelard, educated at the cathedral school of Notre Dame in Paris, was as convinced a theist as Anselm; but his hardy speculations in philosophy and theology - much more than his tragic affair with Heloise - brought him into collision with church authorities. He was a subtle and independent thinker, who contributed significantly to logic and the philosophy of language; some of his insights remained unsurpassed until the 19th century.
Only two other thinkers in 12th-century Europe compared in brilliance with Abelard. One was the Arab Ibn Rushd of Averroes and the other was the Jew Maimonides. Both were natives of Cordoba in Muslim Spain, which remained the foremost centre of artistic and literary culture in Europe. Maimonides was most influential in the philosophy of religion: his Guide for the Perplexed was meant to reconcile the contradictions between the teachings of the Bible and the learning of the philosophers, especially Aristotle, "the summit of human intelligence". It was as an interpreter of Aristotle that Averroes made his name: his voluminous commentaries mediated to the Latin Middle Ages the works of the man who was henceforth to be known as "The Philosopher" par excellence.
At the beginning of the millennium the only works of Aristotle available in Latin were a couple of basic treatises in logic. Towards the end of the 12th century, translations from Greek or Arabic appeared of all his works on logic, physics, biology, psychology, metaphysics and ethics. They were accompanied by Latin versions of substantial portions of Averroes's commentaries. Initially these products of Greek paganism, gift-wrapped in Muslim commentary, were regarded with suspicion by Christian authorities; but they were to dominate European thought until half-way through the millennium.
Simultaneous with the reception of Aristotle, there took place a development of even greater importance for the world's intellectual history: the establishment of the first universities. The university as we know it today is a medieval invention, if by "university" we mean a corporation of people engaged professionally, full-time, in the teaching and expansion of a corpus of knowledge, according to an agreed syllabus, conferring qualifications on the basis of agreed professional standards. Most of the universities throughout the world today can trace their ancestry to four universities established towards the end of the 12th century, in Bologna, Paris, Salerno and Oxford.
Unlike the cathedral and monastic schools that preceded them, medieval universities were open to students from all over the continent. Someone who was licensed to teach in one university could teach in any university and, in an age when all academics used the common language of Latin, there was considerable migration of graduates. (Too much for some universities: Bologna, in a desperate attempt to halt a brain drain, at one time threatened with the death penalty any professor over 50 who left to teach elsewhere.) A typical medieval university had four faculties: the universal undergraduate faculty of arts, and the three higher faculties of theology, law, and medicine, each linked to a profession. The teaching programme was built around set texts: in theology, the Sentences of the Paris bishop Peter Lombard, an anthology of authoritative quotations from the Bible and church documents; in law, Justinian's codification of Roman law, and the compendium of canon or church law drawn up about 1150 by the Bolognese monk Gratian. In medicine, different texts were used in different universities. In the faculty of arts, eventually, it was the works of Aristotle that provided the canon and defined the syllabus: psychology would be studied through lectures and commentaries on his On the Soul, physics, or "natural philosophy" through working on the text of his Physics or On Generation and Corruption, and so on.
It took time, though, for the universities to lose their initial hostility to Aristotle: an edict of Paris in 1210 forbade lectures on his natural philosophy, and ordered his texts to be burnt. The condemnation was reinforced by papal bulls; but by 1255 it had become a dead letter, and most of his known works were soon compulsory parts of the syllabus in arts.
The person who, more than anyone else, made Aristotle respectable in Christian eyes was Thomas Aquinas, whose life almost exactly straddles the mid-point of the half-millennium. Aquinas was a Dominican friar, a member of one of the new religious orders of begging ("mendicant") preachers whose foundation was initially almost as important for the intellectual history of Europe as the institution of the university. In the first years of the 13th century St Francis founded the order of Friars Minor ("Greyfriars", who wore brown) and St Dominic established the Order of Preachers ("Blackfriars", who wore more white than black). By 1219 both orders were established in the University of Paris and from that time until the Reformation almost all the most distinguished philosophers and theologians came from one or other order of friars.
Aquinas was not only a most perceptive commentator on the works of Aristotle, but in his own right an original thinker of great power, a theologian to rival St Augustine and a philosopher of the same calibre as Descartes or Kant. His surviving works add up to nearly nine million words; best known are his two encyclopedic syntheses, the Summa contra Gentes (against the errors of the Infidels), some 325,000 words long, and the Summa Theologiae, which, in a million and a half words, expounds his mature thought at even greater length.
By making a distinction between matters of faith, which can be learnt only through a divine revelation such as the Bible, and matters of philosophy, which can be reached by the unaided operation of the human reason, Aquinas achieved a working relationship between Aristotelianism and Christianity. Within the area of philosophy itself he developed and modified Aristotle's ideas, and while his treatment of logic and natural philosophy has been antiquated by later progress, his contributions to metaphysics, philosophy of religion, philosophical psychology and moral philosophy are full of insights that are as valuable today as in the 13th century.
Aristotle had been a scientist as well as a philosopher; he can indeed claim to have been the founder of several of the life sciences, and some of his zoological observations remained impressive until the time of Charles Darwin. But in the Middle Ages, while the reception of his works was a great boon to philosophy, the influence of his scientific works was damaging to science. Many medieval Aristotelians took Aristotle's writings as the last as well as the first word on scientific matters, instead of following his own example of close examination of nature itself.
Some of the earliest medieval pupils of Aristotle were indeed serious scientists. Robert Grosseteste, Bishop of Lincoln and chancellor of Oxford in the first half of the 13th century, studied the nature of light and was aware of the importance of mathematics in the explanation of reflection and refraction. He wrote on tides and on the rainbow, and he proposed a reform of the calendar that was not implemented until 1582.
In the next generation, the Franciscan Roger Bacon claimed to have spent, over ten years, more than Pounds 2,000 in the purchase of books, scientific instruments, astronomical tables and the like for purposes of research. For Pope Clement IV he wrote a massive research proposal that covered geometry, astronomy, statics, alchemy, agriculture and medicine, emphasising mathematics as the key to all other sciences.
Meanwhile, on the continent, St Albert the Great wrote voluminously on astronomy, chemistry and physiology. He was the most learned man of the first half of the millennium and a remarkable teacher: in Paris he had to lecture in the open air because no hall was large enough to hold his audience. He produced a vast compendium of natural history, including first-hand descriptions of various species of animals and birds.
Most medieval writers, however, were content to take their scientific information second-hand from Aristotle. All knew that the earth was round (indeed Aquinas takes this as a stock example of a scientific truth, ascertainable by a variety of methods); but they believed that it was the centre of the universe, surrounded by concentric spheres, like onion skins, which carried the plants, the moon and the sun in their journeys around the heavens. An outer sphere carried the fixed stars, and all the spheres were moved by a source of movement not itself in motion, namely God. The heavenly bodies and the spheres which carried them were made out of an imperishable crystalline substance quite different from the materials to be found in our sublunar world. Earthly bodies were made up of four elements: earth, water, air and fire, each characterised by the possession of a unique pair of the primary qualities of heat, cold, wetness and dryness. Each element had its natural place in an ordered cosmos, a home to which it tended by a natural motion: thus earthy solids fell while fire rose ever higher.
But while the authority of Aristotle kept fundamental science static for much of the Middle Ages, numerous technological developments enabled medieval folk to surpass their predecessors. In the 11th and 12th centuries the horse-drawn iron plough and the threefold rotation of crops produced an agricultural revolution. The pointed arch and the flying buttress, first employed near Paris in the 1140s and quickly spreading throughout Europe, permitted the creation of the light, soaring, airy cathedrals that are the most tangible surviving glory of the medieval era. From the 1140s the use of paper, introduced into Europe through Muslim Spain, everywhere began to replace parchment and pergamon, greatly facilitating the communication of information.
In the 12th century, however, much of the energy of Christian Europe was dissipated in the costly, and ultimately futile, military ventures of the Crusades. That century had begun with the bloody recovery of Jerusalem from the Saracens in the First Crusade. It ended with the Fourth Crusade, whose only achievement was the sacking of the Greek Christian capital of Constantinople. Expeditions projected with devout intent were disfigured by avarice, treachery, cruelty and massacre, until they became paradigms of unjust warfare. One small compensation was that surgery, in this age of knightly battles and knightly wounds, began to thrive despite ecclesiastical discouragement.
It was in the 13th century that the most lasting contributions of the Middle Ages were achieved. Within a comparatively peaceful Christendom, individual nations began to take shape and to establish their national institutions. In England, the year 1215 saw the signing of Magna Carta, and in 1258 Simon de Montfort convened the first English Parliament. In Italy a vernacular literature grew up, which culminated in Dante's great Divine Comedy, set in the final year of the century. As the century drew to its close, Dante's friend Giotto began to paint in a novel way, linking the theocentric Byzantine icons of the past with the future Renaissance. While the achievement of Aquinas straddled the middle of the century, at its turn Oxford and Paris listened to the lectures of his Franciscan successor, John Duns Scotus, most subtle of all the schoolmen, a philosopher whose influence, often unsuspected, lingers on into the present era.
The universities continued to thrive through the first half of the 14th century. A group of thinkers at Merton College, Oxford, called the Calculators, explored the nature of motion and change, expansion and contraction, with particular reference to infinity and continuity. They developed diagrammatic methods of representing the interaction of motion, time and distance, and in this way laid the foundation for the revolution in physics associated with better-known later names such as that of Galileo. In Paris, Jean Buridan challenged Aristotle's theory of natural motion, thus opening the way to the realisation that moving bodies tend to persist in their motion unless acted on by external forces. Nicole Oresme explored the hypothesis that the earth rotated daily on its axis.
Marsillius of Padua, like Buridan a rector of Paris University, wrote a textbook of political philosophy that was a classic statement of the doctrine that government is legitimate only if it rests on the consent of the governed.
From about 1348, the year of the Black Death, the universities lost much of their intellectual vigour. In the early Middle Ages the universal use of Latin made academic communication and exchange easy, and the teachers who belonged to the mendicant orders enjoyed access to a continental network of communities. The Hundred Years' War between England and France interrupted communication between the main universities of Paris and Oxford. With the growth of vernacular languages, while Latin remained the language of academia, it was no longer the vehicle for the most vigorous expression of thought.
English became the language of preaching and writing for many great minds of the late 14th century, such as the group around John Wycliffe. Known as the morning star of the Reformation because of his criticism of the papacy and his role in the production of an English Bible, Wycliffe was the last of the great medieval scholastic philosophers.
After the time of Wycliffe the development of intellectual and cultural life took place largely outside the universities. In the shadow of Dante the countries of Europe produced their early vernacular poets: Petrarch in Italy, Chaucer in England, Villon in France. In Italy and in the Low Countries a series of exquisite painters (such as Fra Angelico, Fra Filippo Lippi, and Jan van Eyck) formed a bridge between the medieval world and the Renaissance. After many centuries in which the main musical expression of western culture was the plainsong settings of liturgical texts, a new musical era began when, in the 1370s, Guillaume Machaut composed the first polyphonic mass.
There is no dividing line between the Middle Ages and the Renaissance, but three events around the middle of the 15th century significantly changed the ethos of European culture. First, Gutenberg's invention of printing with movable type meant that the communication of learning was no longer a prerogative of university lectures and libraries. Second, the fall of Constantinople to the Turks in 1453 brought Greek scholars and Greek manuscripts to Western Europe. This gave a fillip to the new fashion of "humanism", which favoured the study of pagan authors rather than the authors of recent Christian centuries, and preferred to study classical authorities in the original Greek rather than the Latin translations that had provided the syllabus for the medieval universities. And third, the scientific study of seafaring in the school of the Portuguese Prince Henry the Navigator (d. 1460) enabled sailors to reach distant and unknown parts of the world and brought Europe into ever-increasing contact with unfamiliar societies and cultures. From 1492 onward Columbus's exploration of the New World ushered in the new half-millennium.
If we wish to assess the contribution made to human knowledge during the period 1000-1450 we have to distinguish between various elements in the development of scientific understanding. If a field of phenomena is to be studied scientifically, it must be subjected to conceptualisation, quantification, observation and experimentation. The first step is conceptualisation: in order to formulate, for example, the law of constant acceleration, it is necessary to have a clear grasp of such concepts as "velocity", "rate of increase" and "continuity". If the law is to have purchase on the phenomena of physics, these concepts must carry with them modes of quantification: it must be possible to measure velocity and to quantify its increase over units of time. In order to know whether a scientific law holds or not an essential element is methodical observation, whether (as in astronomy) of data that are outside our control or (as in chemistry) of events that are produced by our own voluntary experimentation.
The medieval period was above all the period of conceptualisation. It was to the elucidation of concepts, and the clarification of the language that expresses them, that the best minds of the age devoted their talents. Despite a theoretical appreciation of the relationship between science and mathematics which goes back to Silvester II and to Roger Bacon, it was not until the Merton Calculators began their investigations into infinity and continuity that the task of quantification was seriously undertaken by any medieval thinker. Despite the energetic efforts of researchers such as Albert the Great, universities in the Middle Ages added little to the corpus of scientific observation that they had inherited from the Greeks and Arabs.
Medieval thinkers were acquainted with almost all the concepts that were later to prove important in the history of science. Through Aristotle they were familiar with the atomic theory of matter first propounded by Leucippus and Democritus in the 5th century BC. While most people in the Middle Ages believed that species had been unchanging since the creation, they knew of the theory of evolution by natural selection, since they had read of the speculations of Empedocles. He had taught that in a primitive stage of the world chance formed matter into isolated limbs and organs: arms without shoulders, unsocketed eyes, heads without necks. These parts linked up by chance into organisms, most of which were fragile or sterile monstrosities; only the fittest structures survived to be the human and animal species we know.
Finally, some medieval thinkers also knew that in the ancient world, Aristarchus had maintained that the earth, far from being the centre of the universe, travels in orbit around the sun. No doubt it was the authority of the Bible and of Aristotle that prevented these ideas from being taken with appropriate seriousness in the medieval period. But in the realm of science these authorities were capable of being overturned, as later centuries were to show. This was possible, however, only when scientific endeavour had progressed beyond conceptualisation to quantification, observation and experiment.l Anthony Kenny, FBA, is author of The Brief History of Western Philosophy, Blackwell (1998).