THE CURRICULA IN THE NEW EUROPEAN UNIVERSITIES WAS, AS WE have learned, largely devoted to the works of Aristotle, whose ideas in many cases ran counter to Roman Catholic dogma, which led to attempts at reconciling the different views, beginning with that of Peter of Abano.
The problem of accommodating Aristotle’s thought to Roman Catholic dogma preoccupied philosophical discussion in western Europe during the thirteenth century. Two scholars in particular dominated this discussion: Albertus Magnus and his even more famous student Thomas Aquinas. As one of their contemporaries wrote of them: “Doubtless many others were famous during this same time both in life and thought. But these two transcended and deserve to be placed above all others.”
Albertus Magnus (c. 1200–1280) was born to a family of the military nobility in Bavaria. He studied liberal arts at the University of Padua, where he was recruited into the Dominican order by its master general, Jordanus of Saxony. He then studied theology and taught in Germany before enrolling in the University of Paris in around 1241, where he lectured on theology for seven years before he was sent to open a school in Cologne. His students included Thomas Aquinas, who came from Italy to study with him, either in Paris or Cologne. Albertus was appointed provincial of the German Dominicans in 1253 and in 1260 he became bishop of Regensburg, a post that he reigned two years later, after which he spent the rest of his life preaching and teaching. He took part of the Second Council of Lyons in 1274, and three years later he went to Paris. There he tried to stop the condemnation of Aristotle’s doctrines by Pope John XXI, in which some of the ideas of his student Thomas Aquinas were questioned, particularly concerning the absolute power of God, which theologians felt was being limited by Thomas.
Albertus seems to have begun studying the works of Aristotle when he first came to teach in Paris. It was probably then that he began his monumental compendium of all the works of Aristotle known at the time, as well as those of the so-called Pseudo-Aristotle. Together these make up seventeen of the forty volumes in the critical edition of Albertus’s works. He undertook this task at the request of his Dominican brethren, who wanted to explain, in Latin, the principal Aristotelian physical doctrines. As he wrote in the prologue to his commentary on Aristotle’s Physics, his purpose was “to make all parts of philosophy intelligent to the Latins.”
He went far beyond the request of his brethren, explaining not only the natural sciences but also mathematics, logic, metaphysics, ethics, and politics, adding in his commentaries all that he had learned of Graeco-Arabic science and philosophy. His synthesis also included what he knew of Plato’s thought as well as his comments on a number of Neoplatonic writings. His acceptance of the basic Aristotelian system is clear in his rejection of Platonic and Pythagorean ideas in cosmology and natural philosophy. Nevertheless, he does not hesitate to disagree with Aristotle or Aristotelian commentaries when he thinks they are wrong. As he wrote, disagreeing with the view of some contemporaries that Aristotle was infallible: “Whoever believes that Aristotle was a god, must also believe that he never erred. But if one believes that he was a man, then doubtless he was liable to error just as we are.” Albertus’s Summa theologica, for instance, contains a listing of Aristotle’s errors, and in his Meteorology he notes at one point that “Aristotle must have spoken from the opinions of his predecessors and not from the truth or demonstration of experiment.”
He believed that sound was caused by the impact of two hard bodies, producing vibrations that are propagated spherically. He performed simple experiments to see how sunlight produced thermal effects, such as showing that a black object will become hotter than a mirror, and he speculated, correctly, that refraction of rays from the sun played a role in the formation of rainbows. Writing on this matter, he corrected Aristotle’s statement that a lunar rainbow occurs only twice in fifty years, noting, “I myself have observed two in a single year.”
Through his researches and writing, Albertus played a crucial role in rediscovering Aristotle and making his philosophy of nature acceptable to the Christian West. The main problem involved in the Christian acceptance of Aristotle was the conflict between faith and reason, particularly in the Averroist interpretation of Aristotelian philosophy with its determinism and its view of the eternity of the cosmos. Albertus sought to resolve this conflict by regarding Aristotle as a guide to reason rather than an absolute authority, and where he conflicted with either revealed religion or observation, then he must be wrong. He held that natural philosophy and theology often spoke of the same thing in different ways, and so he assigned to each of them its own realm and methodology, sure that there could be no essential contradiction between reason and revelation.
One of the objections to Aristotle by theologians was that his system limited the power of God, whom they believed was omnipotent and could thus, for example, have created a multiplicity of universes. Albertus, following Aristotle, concluded that “it is impossible that there be several worlds,” adding that he was referring only to what is impossible in nature, for “there is a great difference between what God can do by means of his absolute power and what can be done in nature.” He felt that natural science should not be concerned with what God is capable of doing, but only with what he actually has done, for after the act of creation the world functions “according to the inherent causes of nature.”
Both Albertus and Aquinas differed from their two famous contemporaries at Oxford, Robert Grosseteste and Roger Bacon, in that they were more purely Aristotelian in their philosophy, whereas the latter took a more Platonist view. Grosseteste and Bacon believed that the principles of natural science are essentially mathematical, while Albertus held that mathematics is an abstract science whose application must be evaluated by the science that studies nature as it actually exists, “in motion and in concrete detail.”
Albertus’s ideas concerning motion and gravitation are essentially Aristotelian. He mentions the term impetus when discussing projectile motion, but refers to it as coming from the medium rather than residing in the moving body, following Aristotle. He also follows Aristotelian theory in explaining the acceleration of a falling body, saying that it speeded up as it approached earth because of its increasing desire to be in its natural place.
Albertus also speculated that the Milky Way is made up of a multiplicity of stars and that the dark areas on the moon are due to surface configurations and not the earth’s shadow, ideas that would be verified by Galileo in his first observations with a telescope. Albertus’s treatise on comets makes use of simple observations to verify or reject theories that had been proposed to explain them, correctly concluding that they were celestial objects moving in the earth’s atmosphere. He followed earlier thinkers in explaining tides as being due to the motion of the moon and favored the Ptolemaic theory of planetary motion. He was aware of the precession of the equinoxes, though he wrongly attributes its discovery to Aristotle rather than Hipparchus.
The most original contributions made by Albertus are in botany and the life sciences, where his work was distinguished by his acute observations and skill in classification. He was the first Latin scholar known to have made use of what became the modern scientific method, the combination of theory, in his case Aristotelian syllogisms, and experimental observation. This is evident in his De vegetabilibus et plantis, an encyclopedic commentary on the pseudo-Aristotelian De plantis, which was the principal source of botanical knowledge in Latin Europe down to the sixteenth century. Discussing the native plants known to him, he wrote: “In this sixth book we will satisfy the curiosity of the students rather than philosophy.… Syllogisms cannot be made about particular natures, of which experience (experimentum) alone gives certainty,” where he was referring to his observations of particular plants as compared to conclusions regarding them arrived at through Aristotle’s teleological theory.
Writing of Albertus’s “digressions” in De vegetabilibus, science historian A. C. Crombie remarked that they “show a sense of morphology and ecology unsurpassed from Aristotle and Theophrastus to Cesalpino and Jung.”
Albertus followed the main outlines of the classificatory scheme that Theophrastus had laid out in his Inquiry into Plants, in which plants were classified into trees, shrubs, undershrubs, and herbs, with finer distinctions such as those between cultivated and wild, flowering and flowerless, fruit-bearing and fruitless, deciduous and evergreen.
The appearance of new species had been the subject of speculation since the time of the first Ionian philosophers of nature. Anaximander thought that all life had originated by spontaneous generation from water and that mankind had developed from fish. Most other ancient writers held that the succession of new species was generated from a common source such as the earth, rather than by modification by living ancestors. Albertus followed Theophrastus in believing that existing types were sometimes mutable, describing five ways in which one plant can be transformed to another, including grafting, the domestication of wild plants, and the running wild of cultivated plants.
Albertus’s De animalibus is a good example of the way in which he and other medieval natural philosophers used the translations and commentaries on the works of Aristotle and other Greek writers to make their own observations and give modified explanations. The first nineteen of the twenty-six books of De animalibus are a commentary on Aristotle’s History of Animals, Parts of Animals, and Generation of Animals, all in Michael Scot’s translation. Albertus’s commentary also makes use of ibn Sina’s own commentaries on these works, of ibn Sinas’s Canon, based on Galen, and of Latin translations of some of Galen’s works. The last seven books of De animalibus consist of original discussions by Albertus on various biological topics, as well as descriptions of particular animals, taken partly from Thomas of Cantimpré’s De rerum natura (c. 1228–1244).
Thomas of Cantimpré’s De rerum natura contains a description of herring fisheries and the hunting of seals, walruses, and whales, as well as a section on fabulous animals. This was one of a number of encyclopedias on agriculture and nature that appeared in the thirteenth century and the first half of the following century, others being treatises on animal husbandry by Walter of Henley and Peter Crescenti, the sections on agriculture in the encyclopedias of Albertus’s De vegetalibus and the Speculum Doctrinale of Vincent of Beauvais, and the botanical and zoological sections in Bartholomew the Englishman’s The Nature of Things, which may be the source of Shakespeare’s natural history. These encyclopedias are evidence of a lively interest in nature also shown in the art, architecture, and books of the period, as in illuminated and illustrated manuscripts, herbals, paintings, mosaics, and reliefs, as well as in the menageries and zoological gardens kept by kings, princes, and even towns. These were not just hobbies and elite studies, but more the result of a renewed interest in nature in western Europe during the late medieval era, leading to the revival of the life sciences in the seventeenth century.
Albertus’s own researches in embryology are described in De animalibus as digressions in his commentary on Aristotle’s Generation of Animals. There, in book 5, he gives a remarkable description of the life history of a butterfly or moth based on his own observation.
He also gave excellent descriptions of a large number of northern animals unknown to Aristotle, noting, for example, the varieties of color of the squirrel, changing from red in Germany to gray in Russia, and the lightening in hue of falcons, jackdaws, and ravens in cold climates.
Albertus’s geology comes mostly from Aristotle’s Meteorologica, the Pseudo-Aristotelian De elementiis, and Avicenna’s De mineralibus, but he adapted these authorities to formulate a coherent theory and added observations of his own. He extended Avicenna’s account of fossils, for example, giving his own explanation in his De mineralibus et rebus metallica: “There is no-one who is not astonished to find stones which, both externally and internally, bear the impression of animals. Externally they show their outline and when they are broken open there is found the internal parts of these animals. Avicenna teaches us that the cause of this phenomenon is that animals can be completely transformed into stones and particularly into salt stones.” This did not create any problems with the Church, for there was nothing in this work that would seem to be in conflict with its dogmas.
Albertus was also interested in alchemy and performed a number of chemical experiments, compiling a list of the properties of some one hundred minerals. His theory of the structure of matter includes the concept of elements in compounds, and he is said to have been the first to isolate the element arsenic.
Although Albertus was very modern in his scientific thinking, he was still medieval in his views on such matters as magic, divination, and astrology. He wrote in his Summa theologica of his belief that magic is due to demons. “For the saints expressly say so, and it is the common opinion of all persons, and it is taught in that part of necromancy which deals with images and rings and mirrors of Venus and seals of demons.” Albert writes of astrology in almost all of his scientific treatises, describing the effects produced by such celestial phenomena as conjunctions of the planets, to which he attributes “great accidents and great prodigies and a general change of the state of the elements and of the world.”
Ulrich Engelbert of Strasburg, a pupil of Albert’s, described him as “a man in every science so divine that he may well be called the wonder and miracle of our time.” Thomas Aquinas wrote of him with equal admiration, saying, “What wonder that a man of such whole-hearted devotion and piety should show superhuman attainments in science.” Albert was canonized by Pope Pius XI on December 16, 1931, and ten years later Pope Pius XII declared him the patron saint of all those who cultivate the natural sciences.
Thomas Aquinas (c. 1225–1274) was born near Monte Cassino in southern Italy, where his father served the emperor Frederick II in his war against the papacy. He began his education at the Benedictine abbey of Monte Cassino, after which he went to the newly founded University of Naples, where he was introduced to the works of Aristotle. After joining the Dominicans, he was sent for further studies to Cologne and then Paris, where his teachers included Albertus Magnus. Studying under Albertus, Thomas soon mastered the most recent scholarship of his time, including the major Greek and Arabic works that had been translated into Latin.
Thomas spent two periods as professor at the University of Paris, 1256–1259 and 1269–1272, and in the interim he was associated in turn with the papal courts of Alexander IV, Urban IV, and Clement IV. After his second professorship in Paris he returned to Naples to start a Dominican school, which he directed until a few months before his death in 1273. He was canonized by Pope John XXII on July 18, 1323, and was subsequently presented by the Roman Catholic Church as the most representative teacher of its doctrines. His philosophical system, known as Thomism, is still taught at Catholic universities, and I first studied it as an undergraduate at Iona College in New Rochelle, New York.
Thomas continued Albertus’s program of assimilating Aristotle’s philosophy and adapting it to Roman Catholic dogma as he interpreted it. His own synthesis of pagan and Christian thought is definitively expressed in his massive Summa theologica, which he was still working on at the time of his death. One of the questions he addresses in this work is the difference between a hypothesis that must necessarily be true, such as a physical or metaphysical hypothesis, and one that merely fits the observed facts, such as a mathematical hypothesis. An example of a metaphysical hypothesis was the Aristotelian view that the celestial bodies are embedded in a set of concentric crystalline spheres rotating around the earth with constant velocity. A mathematical hypothesis, on the other hand, was the Ptolemaic system of eccentrics and epicycles to fit the observed motions of the sun, moon, and planets.
As it turns out, both of these hypotheses are false, as Copernicus, Galileo, Kepler, and Newton were to show. But Thomas thought that a physical or metaphysical hypothesis, such as Aristotle’s view that celestial bodies rotate around the earth with constant velocity, must necessarily be true because “sufficient reason can be brought to show that the motions of the heavens are always of uniform velocity.” He went on to say that a mathematical hypothesis, such as the Ptolemaic theory of cycle and epicycles, “is not a sufficient proof, because possibly another hypothesis might be also be able to account for them.”
Thomas, like Albertus Magnus, tried to resolve the conflict between theology and natural science and show that there could be no real contradiction between revelation and reason. Arguing against those who said that natural philosophy was contrary to the Christian faith, he wrote in his treatise on Faith, Reason, and Theology that “even though the natural light of the human mind is inadequate to make known what is revealed by faith, nevertheless what is divinely taught to us by faith cannot be contrary to what we are endowed with by nature. One or the other would have to be false, and since we have both of them from God, he would be the cause of our error, which is impossible.”
Many of the problems involved in adapting Aristotle to Catholic dogma were addressed by Thomas in two of his books: On the Eternity of the World and On the Unicity of the Intellect Against the Averroists. Thomas, in the first of these books, says that we know from divine revelation that the world was created at a moment in time, but philosophy cannot settle the problem one way or the other, since the question of creation ex nihilo is one that cannot be proved by using natural reasons but depends on faith alone. The second book presents Thomas’s arguments against the Averroist concept revived by Siger of Brabant, a radical lecturer at the University of Paris, of monopsychism, that is, the notion that the human soul is not confined to a single person but is a unitary intellect shared by all humans, and what survives after the death of the individual is not personal but collective.
After Thomas published his work On the Unicity of the Intellect, Siger modified his views to conform them to Catholic teaching. Nevertheless, Siger insisted that his ideas were necessary philosophical conclusions, but since they conflicted with Catholic views, the dogma of the Church must prevail. Siger wrote: “One should not try to investigate those things which are above reason or to refute arguments for the contrary position. But since a philosopher, however great he may be, may err on many points, one ought not to deny the Catholic faith because of some philosophical argument, even though he does not know how to refute it.”
Boethius of Dacia (fl. 1270), a member of Siger’s circle, wrote the treatise On the Eternity of the World, in which he set out to refute the notion of creation, arguing in favor of the Aristotelian idea of a universe that had no beginning in time. Having done so, he made it clear that he himself, as a Christian, accepted the doctrine of creation as a matter of faith. Nevertheless, he argued that the philosopher is bound to examine any matter that lends itself to rational explanation. As he wrote: “It belongs to the philosopher to determine every question which can be disputed by reason; for every question which can be disputed by rational argument falls within some part of being. But the philosopher investigates all being—natural, mathematical, and divine. Therefore it belongs to the philosopher to determine every question which can be disputed by rational argument.”
Although Aristotle’s works formed the basis for most nonmedical studies at the new universities, some of his ideas in natural philosophy, particularly as interpreted in commentaries by Averroës, were strongly opposed by Catholic theologians. One point of objection to Aristotle was his notion that the universe was eternal, which denied the act of God’s creation; another was the determinism of his doctrine of cause and effect, which left no room for divine intervention or other miracles. Still another objection was that Aristotle’s natural philosophy was pantheistic, identifying God with nature, which derived from the Neoplatonic interpretation of Aristotelianism by Avicenna (ibn Sina).
This led to a decree, issued by a council of bishops at Paris in 1210, forbidding the teaching of Aristotle’s natural philosophy in the university’s faculty of arts. The ban was renewed in 1231 by Pope Gregory IX, who issued a bull, or papal decree, declaring that Aristotle’s works on natural philosophy were not to be read at the University of Paris “until they shall have been examined and purged from all heresy.” The ban was apparently not enforced, and in any event it seems to have remained in effect for less than half a century, for a list of texts used at the University of Paris in 1255 includes all of Aristotle’s available works.
The controversy was renewed in 1270, when the bishop of Paris, Etienne Tempier, condemned thirteen propositions derived from the philosophy of Aristotle or from Aristotelian commentaries by Averroës. This gave rise to the notion of “double truth,” in which an idea might be true if demonstrated by reason in physics and metaphysics, while a contradictory concept could be independently true in theology and the realm of faith. Pope John XXI, after seeking the advice of theologians, issued a bull in 1277 in which he condemned 219 propositions, including the original 13 listed by Tempier, threatening excommunication of anyone who held even a single erroneous doctrine. That same year, a similar condemnation was issued by Tempier as well as by the archbishop of Canterbury, Robert Kilwardby, whose edict was renewed in 1284 by his successor, John Pecham. A number of the propositions were declared to be erroneous because their determinism placed limits on the power of God.
The condemnation of Averroist doctrines by the bishop of Paris in 1270 may have been directed against some of the teachings of Thomas Aquinas, one being that the creation of the world cannot be demonstrated by reason alone. This and other interpretations by Thomas were his solution to the problem of adapting Aristotelianism to Christian theology. The lengths to which Thomas went is evident in his attempt to fit the biblical account of the Ascension into the Aristotelian cosmos. According to Ephesians 4:10, Christ “ascended up far beyond all heavens, that he might fill all things,” which presented problems for Thomas in trying to square this with Aristotle’s philosophy and his model of the homocentric crystalline spheres.
Such were the efforts that Thomas made to adapt Aristotle’s system of the world to Catholic theology. Despite the condemnations that were made in the thirteenth century, the works of Aristotle continued to dominate the curriculum at Paris and other universities. A regulation adopted at the University of Paris in 1341 required all new masters of arts to swear that they would teach “the system of Aristotle and his commentator Averroës and of the other ancient commentators and expositors of the said Aristotle, except in those cases that are contrary to the faith.” By that time Aristotelian philosophy had become the basis for undergraduate studies and in the graduate programs in medicine, law, and theology in all European universities, as well as providing the foundation for philosophical discussion and scientific research. This was the culmination of what can be termed the conversion of Aristotle to Christianity, which historian David Lindberg credits largely to the effort of Thomas Aquinas in solving the problem of faith and reason.
This, then, is Thomas’s solution to the problem of faith and reason. He had made room for both, subtly merging Christian theology and Aristotelian philosophy into what we may call “Christian Aristotelianism.” In the process it was necessary for Thomas to Christianize Aristotle by wrestling with the Aristotelian doctrines that appeared to conflict with the teaching of revelation and correcting Aristotle where he had fallen into error; at the same time he “Aristotelianized” Christianity, importing major portions of Aristotelian metaphysics and natural philosophy into Christian theology. In the long run Thomism came to represent the official position of the Catholic Church; in the short run Aquinas was viewed by theologians of more conservative persuasion as a dangerous radical.
A drawing of Saint Albertus Magnus by Tommaso da Modena
A painting of Saint Thomas Aquinas by Fra Angelico
Albertus Magnus and Thomas Aquinas had in effect converted Aristotle to Christianity, so that Aristotelianism, with its static and earth-centered cosmology, represented the worldview of western Europe up until the seventeenth century, by which time the works of Copernicus, Galileo, Kepler, and Newton brought about its downfall.
Meanwhile Aristotelianism remained the basis of higher education and scientific research in western Europe, where at the beginning of the thirteenth century scholars would begin to develop a new philosophy of nature and a scientific method based on observation and experiment, while at the same time their thinking was still rooted in the works of Aristotle, as they walked a tightrope to avoid conflict with Church dogma.