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"Medieval Science," Oxymoron? Think Again - Part 3 of 3


A surge of scientific creativity and innovation burst forth as a result of the inflow of Greco-Arabic learning into Western Europe.

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In fact, the 13th-century witnessed the rise of several important natural philosophers who excelled in optics, biology, mathematics, alchemy, mechanics, and astronomy: Robert Grosseteste (1168-1253), Roger Bacon (1220-1292), Albert the Great (1200-1280), otherwise known as Albertus Magnus, John Pecham (d. 1292), Witelo (d. after 1281), Leonardo Fibonacci (1170-after 1240), Paul of Taranto, Peter Peregrinus, John Sacrobosco (1195-1256), Jordanus Nemorarius, and Gerard of Brussels. The following passages shall discuss each one of these scholars.

13th-century Natural Philosophers

Grosseteste, "one of the most knowledgeable men of the Middle Ages" (Woods 95), was a distinguished English scholar who served as the bishop of Lincoln and as the first chancellor of the Oxford University. He mastered the mathematical sciences and translated some of the classics. Like many Franciscan friars of the 13th century, he was fascinated by the nature of light, believing it was divine. Therefore, he was convinced that understanding light was key to understanding something about the creator. He regarded geometry as essential for natural philosophy because he believed the universe consisted of lines, figures, and angles. In addition, Grosseteste was conversant with Aristotle's texts, including Physics, Metaphysics, Meteorology, and the biological writings, the influence of which is evident in some of his short treatises on physical subjects. He wrote a commentary on Aristotle's Posterior Analytics, "one of the earliest efforts to deal seriously with Aristotle's scientific method" (Lindberg's Beginnings 234). He is believed to have played a crucial role in the introduction of the experimental method in the West. Watson explains: "Grosseteste's main insight, building on Aristotle, was to develop his model of 'induction' and systematic testing. He said that the first stage of an inquiry was to break up the phenomenon under investigation into the principles or elements of which it was comprised — this was induction. Having isolated these principles or elements, one should recombine them systematically to build up knowledge of the phenomenon" (329). 

English philosopher and Franciscan friar Roger Bacon, nicknamed Doctor Mirabilis ("wonderful teacher"), admired Grosseteste and was inspired by his vast scholarly interests and knowledge. In the 1240s, Bacon started lecturing at the faculty of arts in Paris where he was the first to teach Aristotle's books on natural philosophy. He is often considered one of the earliest advocates of the scientific method in the West, as he stressed the importance of observation and experiment. In Opus maius, which he presented to Pope Clement IV, Bacon advances the claim that even the best theory remains incomplete as long as it is not validated by experiment: "Without experiment, nothing can be adequately known. An argument proves theoretically, but does not give the credence necessary to remove all doubt; nor will the mind repose in the clear view of the truth, unless it finds it by way of experiment" (Woods 94). Elsewhere, in his Opus Tertium to be precise, he affirms that the "strongest argument proves nothing, so long as its conclusions are not verified by experience" (94). 

Bacon's importance in the history of medieval science lies in his massive efforts to defend and justify the need to study the new scientific and philosophical knowledge pouring in from the Muslim world. He sought to stress to church hierarchy the utility and benefits of natural philosophy, mathematics, and medicine. He proposed a number of cogent arguments in support of his position. He charged, for example, that scientific knowledge enhanced understanding of the biblical text; that astronomy was essential for establishing the religious calendar; that optical studies could lead to the invention of devices that would strike terror into the enemies of Christianity; that astrology enabled man to predict the future, etc. He ruled out any conflict between faith and natural philosophy, and invoked the authority of St Augustine and other Church fathers who had sanctioned the study of pagan texts. Despite his passion for science, it should be noted that Bacon continued to highlight the primacy of theology and accorded natural philosophy the handmaiden status in the sense that its main function was to promote religious goals. On his role in the establishment of experimental science in the Latin West, Lindberg says that Bacon

"does not deserve the reputation of 'founder of experimental science' often bestowed on him. However, he did become an influential propagandist for empirical methodology, advocating the gathering of empirical evidence in all of the sciences. He argued that the first prerogative of experimental science is to verify conclusions drawn from arguments within the other sciences by submitting them to the test of experience; and it is clear from various publications that he practiced what he preached" (Beginnings 363).

Bacon is said to have made the earliest reference to gunpowder in Europe. In Opus Tertium, he mentions this explosive device which had arrived in the West from China during the Middle Ages: 

"There is a child's toy of sound and fire made in various parts of the world with powder of saltpetre, sulphur and charcoal of hazelwood. This powder is enclosed in a packet of parchment the size of a finger. This can make such a noise that it seriously distresses the ears of men, especially if one is taken unawares, and the terrible flash is also alarming. If an instrument of large size were used, no one could stand the terror of the noise and flash. If the instrument were made of solid material then the violence of the explosion would be much greater" (Hannam 140).

He also forecast many modern inventions like airplanes and automobiles. In a letter entitled On the Marvelous Power of Artifice and Nature, he writes the following: 

"It is possible that a car shall be made that will move with inestimable speed and the motion will be without the help of any living creature…It is possible that a device for flying shall be made such that a man sitting in the middle of it and turning a crank will cause artificial wings to beat the air after the manner of a bird's flight" (141).

Following Grosseteste's example, Bacon showed particular interest in the field of optics, especially the work of the Arab medieval scientist Ibn al-Haytham (965-1040), commonly known as Alhazen, whose seven-volume Book of Optics (Kitab al-Manazir or De aspectibus) was destined to have a monumental impact on the West for centuries. Bacon speculated on the magnifying qualities of lenses, and like Grosseteste, thought that a better understanding of light and its properties could give access to God's mind. He proposed that light traveled in straight lines and that its speed was very fast but finite. Bacon dissected and capitalized on the new body of Greco-Arabic writings on the science of light that had recently become available in the Latin West by the mid-13th century. He was indeed much influenced by Alhazen's intromission theory (light enters the eye from the outside) and the mathematical aspect of his analysis of light and vision. At the same time, he did not entirely turn his back on the theories of the ancient Greeks. Rather, he set out to blend all the optical theories of his Greek and Arab predecessors (including Aristotle, Euclid, Ptolemy, the Neoplatonists, and Alhazen) into a coherent synthesis or whole, working out discrepancies and points of conflict, particularly between proponents of the intromission and extramission (vision occurs as a result of the emission of light from the eyes) theories. On the way Bacon managed to pull off this daunting task, Lindberg explains:

"Regarding the direction of radiation (from or toward the eye — the point of contest between the extramissionists and the intromissionists), Bacon agreed with Alhazen and Aristotle that vision occurs only through intromitted rays. What then of the extramitted rays advocated by Plato, Euclid, and Ptolemy?  Clearly they could not be responsible for vision, but they could still exist and play an auxiliary role in the visual process — that of preparing the medium to receive the rays emanating from the visible object and of ennobling the incoming rays to the point of where they could act on the eye. Regarding the nature of radiation, Bacon accepted the Neoplatonic conception of the universe as a vast network of forces, in which every object acts on objects in its vicinity through the radiation of a force or likeness of itself. Moreover, he conceived this universal force to be the instrument of all causation and, on this basis, developed (what proved to be) an influential philosophy of nature. As for light and color, Bacon argued that they (and any other visible agents discussed by the optical authors) were likeness of their sources and thus manifestations of this universal force" (Beginnings 318, 320).

Two of Bacon's contemporaries, who shared his fascination with optics and played a dominant role in disseminating Alhazen's optical theories in the West, were John Pecham and Witelo. Pecham was a Franciscan friar who served as Archbishop of Canterbury and wrote Perspectiva communis, "by far the most popular optical text in the medieval universities" (Lindberg's Beginnings 319). So popular was his work that it remained an integral part of university curriculum down into the sixteenth century. For his part, the Polish theologian and natural philosopher Witelo wrote an optical book that relied heavily on Bacon's writings and combined all the Greek and Arab optical theories. His work "remained the last word on perspective until the sixteenth century when…it formed the foundation of modern optical theory" (Hannam 145). Another European scholar who pushed forward the frontiers of optical knowledge was the Dominican theologian and natural philosopher Theodoric of Freiburg (d. 1310). He conducted an experiment involving a water-filled glass globe in a bid to explain how rainbows were formed. His conclusion was that the formation of rainbows was the result of two refractions and one inner reflection in each droplet of water. Theodoric's Persian contemporary, Kamal al-Din al-Farisi, with whom he apparently had no contacts, replicated the experiment and reached the same results.

The late 13th-century, particularly the year 1286 or thereabouts, witnessed a groundbreaking development, namely the invention of spectacles — an apparent outcome of the significant advances in optical studies throughout the century. Celebrated American historian Will Durant credits an Italian by the name of Salvino d'Amarto with this epoch-making invention (996).  In a sermon he was delivering in Florence at the beginning of the 14th century, a Dominican friar named Giordano of Pisa mentioned spectacles and their inventor:

"It was not twenty years since there was discovered the art of making spectacles that help one see so well; an art which is one of the best and most necessary in the world. And that is such a short time ago that a new art that had never before existed was invented. I myself saw the man who discovered it and practiced it, and I talked with him" (Hannam 146).

The same period in Europe, probably the 1270s, saw the invention of the mechanical clock. In late 13th century and throughout the 14th century, large mechanical clocks were installed in churches, buildings, and public squares in European cities like London, Paris, Milan, Padua, and many others. These two inventions, the spectacle and mechanical clock, are said to have "catapulted medieval Europe into the first place in the race to become the most technologically advanced civilization on earth" (Hannam 146). Other medieval inventions include the blast furnace (1384), handguns in the form of the matchlock musket (shortly before 1500), and of course a much improved version of the printing press in the 15th century.

Another towering figure of the 13th century was the broad-ranging theologian and scholar Albert the Great, nicknamed Albertus Magnus, whose writings spanned a vast repertoire of disciplines, including biology, physics, astronomy, mathematics, medicine, earth sciences, logic, metaphysics, and psychology. Like Bacon and Grosseteste, he highlighted the importance of direct observation and advocated first-hand investigation of causes rather than reliance on the impressions of other scholars. The natural philosopher, he writes in De Mineralibus, is not to "accept the statements of others, that is, what is narrated by people, but to investigate the causes that are at work in nature for themselves" (Woods 95). Albert, hailed as "the best biologist of the entire Middle Ages" (Lindberg's Beginnings 239), made first-hand observations and records of animals and plants. He corrected Persian scholar Ibn Sina on the mating of partridges and, as part of his studies, visited an eagles' nest for six years. 

Albert left a vast body of commentaries on Aristotle and offered the first comprehensive exposition of Aristotelian philosophy in Europe. This achievement earned him the title of being "the effective founder of Christian Aristotelianism" (237). He saw Aristotelian philosophy as a necessary preparation for theological studies and played a key role in dismantling the ban on the study of Aristotle's writings in Paris. Despite his admiration for and reliance on Aristotle, he was not a slavish follower of the Greek philosopher and had no problem correcting Aristotle's conclusions whenever he saw fit. He reasoned that since "one believes him [Aristotle] to be but a man, then without doubt he could err just as we can too" (Grant's Foundations 164). His other achievement was assigning separate realms for theology and natural philosophy. Theological considerations, he thought, should not encroach upon philosophical studies. Like the scholars of the 12th-century Renaissance, he emphasized the autonomy of the laws of nature and believed that the universe operated on the basis of natural causation. Therefore, the task of the natural philosopher was to discover these cause without having recourse to God. He went as far as applying this method to biblical exegesis. Lindberg notes:

"What is remarkable is Albert's willingness to adhere to this methodological prescription even in his discussion of a biblical miracle — Noah's flood. Noting that some people wish to confine the discussion of floods (including Noah's) to a statement of divine will, Albert pointed out that God employs natural causes to accomplish his purposes; and the philosopher's task is not to investigate the causes of God's will, but to inquire into the natural causes by which God's will produces its effect. To introduce divine causality into a philosophical discussion of Noah's flood would be a violation of the proper boundaries between philosophy and theology" (Beginnings 241).

Leonardo Fibonacci, "one of the most important mathematicians of the Middle Ages" (Freely 143), was born in Pisa in 1180. His father served as secretary of the Republic of Pisa and later as manager of a Pisan trading agency in the city of Burgia, Algeria. As a young man, he joined his father in Burgia, studied under a Muslim teacher, learned the profession of the merchants, and became acquainted with methods of calculation and reckoning. He traveled in Egypt, Syria, Greece, and Sicily, and may have learned Arabic and Greek. In any case, he was familiar with the mathematical works of Archimedes, Euclid, Hero, and Diophantus. In 1202, he published his most important work, Liber abaci (Book of Calculation), which constituted "the first thorough European exposition of the Hindu numerals, the zero, and the decimal system by a Christian author" and "marked the rebirth of mathematics in Latin Christendom" (Durant 990). It introduced Arabic algebra to Europe and "made a minor revolution" in this branch by "occasionally using letters, instead of numbers, to generalize and abbreviate equations" (990). His other work, Practica geometriae, published in 1220, was the first in Europe to apply algebra to the treatment of geometrical theorems. Furthermore, he made "original contributions" to the solution of linear and quadratic equations in two short works dating from 1225. In Liber quadratorum (1225), Fibonacci presented what is known as the "rabbit problem."  The problem is as follows: "How many pairs of rabbits will be produced in a year, beginning with a single pair, if in every month each pair produces a new pair which become productive from the second month on?" (Freely 144). His solution to the problem produced what is known as the "Fibonacci numbers" — a series of numbers in which each is the sum of the two numbers preceding it (1, 1, 2, 3, 5, 8, 13, 21, etc), "a mathematical wonder that continues to fascinate mathematicians" (144).

Medieval Europe made advances in alchemy as well. As stated previously, Bacon was the first European to describe gunpowder. In the same century, the Franciscan friar Paul of Taranto, author of Summa perfectionis, the "most influential of all medieval alchemical writings in the Latin West" (Lindberg's Beginnings 292), broke out of the Aristotelian understanding of the elements and proffered an alternative, corpuscular theory reminiscent of, though slightly different to, the atomism of ancient Greek philosophers. Lindberg says: 

"What is important (indeed revolutionary) about this book is the author's adoption of a corpuscular interpretation of the elements. This flies in the face of the standard Aristotelian theory of the elements, which was totally opposed to any sort of atomism or corpuscularianism…According to Paul, the four elements — earth, water, air, and fire — exist in the form of tiny corpuscles. Corpuscles of earth (for example) bond with one another in tight clusters to form larger corpuscles of earth. Though very tightly bonded, the original tiny corpuscles retain their identity within the largest corpuscles. These larger corpuscles of earth then form tight clusters with larger corpuscles of the other elements in various proportions to form the material of which metals and other substances consist. Because the smaller corpuscles retain their identities within the larger corpuscles, they may be called upon as a second causal and explanatory level. The properties of a given substance — a metal, for example — can be attributed either to the original tiny corpuscles or to the larger clusters. If we set aside some of the details, we have here a corpuscular theory of matter resembling that of the ancient atomists, differing in that the 'atoms' of Paul of Taranto do not represent the end of the process of division, but are themselves composites of still smaller entities" (Beginnings 292, 294).

Like several other European natural philosophers of the 13th century, Paul of Taranto engaged in experimentation to test the validity of his alchemical theories. In fact, this Italian monk "initiated an alchemical tradition characterized methodologically by laboratory manipulation of substances in the attempt to discover the pathway to transmutation" (364). His work influenced Daniel Sennert (1572-1637), professor of medicine at the University of Wittenburg, who in turn had some influence on Robert Boyle (1627-1691), one of the stars of the Scientific Revolution and the founder of modern chemistry. The experimental method figures prominently in the work of Bacon's contemporary and French scholar Peter Peregrinus of Maricourt, who experimented with magnets in a bid to understand their properties. His discoveries are believed to have "anticipated many of those that would subsequently be made in the seventeenth century by William Gilbert, often identified as one of the founders of experimental science" (364).

My next figure is the monk and astronomer John of Sacrobosco, also known as John of Hollywood, whose Sphere had served as a central astronomical textbook at the European universities as late as the 17th century, explaining the complexities of Ptolemaic astronomy to generations of students. In The Closing of the Western Mind, historian Charles Freeman erroneously argues that it was the 5th-century Greek scholar Proclus who had made the "last astronomical observation" in the West until 16th-century Polish astronomer Nicholas Copernicus put the earth in orbit around the sun (xix). Freeman's aim is to "prove" that the Middle Ages stunted scientific progress and that astronomy atrophied during this period. Nothing could be further from the truth as John of Sacrobosco's Sphere illustrates only too well. Undoubtedly, Europeans of the early medieval period had no access to the astronomical writings of Ptolemy and Hipparchus, and thus their astronomical knowledge was minimal. Scholars like Martianus Capella and Isidore of Seville offered no more than elementary astronomical information, and as Lindberg points out, "the practice of serious mathematical astronomy [in this period] was nonexistent" (Beginnings 262). That said, the growing contact with the Islamic world from the 10th century forward, especially in Spain, and the acquisition of Greco-Arabic writings through the massive translation movement, dramatically turned the situation up-side-down. Lindberg notes that "[b]y the end of the twelfth century, the most important astronomical texts were available in Latin. The history of Western astronomy from this point forward is a story of growing mastery and increasing dissemination of astronomical knowledge, primarily within the universities" (Beginnings 265-6). 

In addition to John of Sacrobosco's Sphere, one ought to mention a much more sophisticated treatise entitled Theory of the Planets by an unknown author though the assessment is that he was a Parisian teacher. This work is said to have "raised the discussion of planetary astronomy to a substantially higher level" (266). In addition, a group of astronomers at the court of Alfonso X of Castile drew up astronomical tables in 1275 known as the Alfonsine Tables. These tables had "served as the standard guide to the practice of mathematical astronomy until confronted by new competitors in the sixteenth century" (267). Johannes de Muris (1290-1355) — a French philosopher, astronomer, and mathematician who taught at the Sorbone during the first half of the fourteenth century — undertook observations to test and correct astronomical data on planetary motions and positions. His observations of solar eclipses, for example, corrected predictions of the Alfonsine Tables. Medieval astronomy reached its zenith with the great work of two outstanding professors, Georg Peurbach (1423-61) and Johannes Regiomontanus (1436-76). Their Epitome of the Almagest improved on all previous commentaries dealing with Ptolemy's work and had a great impact on Copernicus and his conception of the heliocentric model of the universe.

Aside from writing mathematical treatises in which he used Hindu-Arabic numerals and letters in algebraic formulae, the Dominican monk, mathematician, and physicist Jordanus Nemorarius is said to have "anticipated modern ideas in the mechanics of the lever and the inclined plane" (Durant 995). He laid down a principle known as the Jordanus axiom: "that which can raise a certain weight to a certain height can raise a weight K times heavier to a height K times less" (995). One more 13th-century European scholar I would like to briefly mention is the mathematician Gerard of Brussels who possibly taught at the University of Paris in the first half of the 13th century. His Book of Motion is significant because it offered a mathematical analysis of motion. Gerard was by no means the first scholar to ever attempt to get a mathematical handle on motion, as Aristotle and Autolucus of Pitane had tried their hand at quantifying motion as well. His work did serve, however, as "a harbinger of the kinematic tradition that was to develop in the Latin West" (Lindberg's Beginnings 300).  

14th-century: Culmination of Medieval Science

My discussion now turns to a group of 14th-century English logicians and mathematicians associated with Merton College, Oxford, and recognized as the Merton Calculators. The group was made up of Thomas Bradawrdine (d. 1349), who later served as Archbishop of Canterbury; Richard Swineshead (fl. 1340-1355), nicknamed "The Calculator" and often regarded as "the most talented of the mathematicians at Merton" (Hannam 173); John of Dumbleton (d. 1349); and William Heytesbury (1313-1373). The importance of these scholars cannot be overemphasized, as they "almost certainly beat out the path later followed by Galileo and the other founders of modern science" (170). What is also striking about these mathematicians is that, like Archimedes (287-212 BC), they were fond of speculating on imaginary or hypothetical situations and trying to solve them mathematically.

Bradwardine is an interesting figure in particular. He placed a high value on mathematics, insisted on its incorporation into the study of physics, and viewed numbers as essential to the acquisition of wisdom. He hailed mathematics as "the revealer of every genuine truth, for it knows every hidden secret and bears the key to every subtlety of letters" (171). He added that "[w]hoever, then, has the effrontery to pursue physics while neglecting mathematics should know from the start that he will never make his entry through the portals of wisdom" (171). He set out to translate Aristotle's laws of motion into a mathematical formula, and herein lies his contribution, namely showing that "any physical law worth its salt had to be expressible in mathematical terms" (172). On the issue of falling bodies, Bradwardine speculated on a hypothetical situation in which objects moved in a vacuum, and theorized that a heavy and light object would fall at the same rate in the absence of air resistance.

In examining motion, the Merton scholars distinguished between dynamics and kinematics; while the former is concerned with its causes, the latter deals with its effects or with a purely mathematical description thereof. They also made a distinction between uniform motion or motion at constant velocity and accelerated motion, and came up with a precise definition of uniformly accelerated motion: "a motion is uniformly accelerated if its velocity increases by equal increments in equal units of time" (Lindberg's Beginnings 300). They further discriminated between the quantity (how much of a certain quality there is) and intensity (the degree or strength) of a certain quality, such as heat or weight or motion. "For fourteenth-century mathematicians," says Lindberg, "it followed that all qualities should submit to a similar analysis, possessing both a quantity (how much of the quality) and an intensity (the degree or strength of the quality). For heat, we have temperature (intensity) and calories (quantity); for weight, heaviness (quantity) and density or specific gravity (intensity); and so on" (301). 

The mean speed theorem is the Merton scholars' primary contribution. This theorem, which left an imprint on the history of physics and was used by Galileo in the 17th century, reads as follows: "A moving body will travel in an equal period of time, a distance exactly equal to that which it would travel if it were moving continuously as its mean speed" (Hannam 174). This means that a body (x) moving with uniformly accelerated velocity traverses the same distance at a given time as a body (y) moving for the same duration with uniform velocity equal to the average velocity of body (x). In numerical terms, an object accelerating uniformly from velocity 10 to 30 at a given time covers the same distance as another object moving uniformly for the same duration with a constant velocity of 20. The second theorem states that the distance covered in the first half of a uniformly accelerated motion constitutes a third of the distance covered in the second half of the same motion. 

Buridan and Oresme

Jean Buridan, professor at the Sorbonne and "the most remarkable philosopher of the 14th century" (178), revived the impressed force/impetus theory and introduced the concept of inertial motion, thereby planting the seeds of Newton's 1st law. Buridan rejected Aristotle's explanation as to why an object kept moving in the air after being thrown even though its natural movement should be downward and its natural place should be on the ground. Aristotle attributed the continued, albeit short, movement of the object to the air pushing it from behind. Buridan's alternative theory was that the thrower had impressed a force or impetus upon the object, causing it to move in the air but once the impressed force had dissipated, the object immediately fell to the ground. He formulated the concept of inertia by suggesting that if the object encountered no resistance, it would continue its motion forever. In Buridan's own words, "Impetus would last forever if it were not diminished and corrupted by an opposing resistance or a tendency to contrary motion" (179). His trailblazing explanation looked forward to Newton's 1st law, which refers to the tendency of an object to remain at rest or to continue in motion unless disturbed by another force. That is to say, bodies at rest tend to stay at rest while bodies in motion tend to continue in motion unless acted upon by an external force. Buridan further thought that the magnitude of impetus was proportional to weight and speed, an idea "very similar, but not quite the same as, the concept of momentum in modern physics" (179).

Buridan extended the concept of inertia to the heavens. As a Christian, he dispensed with the Aristotelian idea of an eternal universe and insisted that God had created it out of nothing. The planets, he reasoned, had not been moving forever because their motion had started following creation and at a particular moment in time. He then attempted to figure out what had caused the planets to start moving and how their motion continued though there appeared to be no force propelling it. His conclusion was that God had imparted force or impetus to the planets, causing them to start moving, but planetary motion continued thereafter because it encountered no countervailing force or friction that could slow or stop it. He explained: "In the celestial motions, there is no opposing resistance. Therefore, when God, at the creation, moved each sphere of the heavens with just the velocity he wished, he then ceased to move them himself and since then those motions have lasted forever due to the impetus impressed on the spheres" (180). 

That Buridan applied his idea of impetus and inertia to both terrestrial and planetary motion constituted a rupture with the pagan, specifically Aristotelian, idea that fundamentally different principles governed motion on earth and in the celestial sphere. He also disposed of the pagan idea that the planets had souls or intelligences that were the cause of planetary motion. 

In a departure from the overwhelmingly speculative characteristic of the Greek scientific tradition and in accord with the empirical tendencies of the medieval scientific scholarship, Buridan thought that sensory impressions could be trusted and that natural philosophy should be predicated on observation: "It is evident to us that every fire is hot and that the heavens are moved, even though the contrary is possible by God's power. And it is evidence of this sort that suffices for the principles and conclusions of natural philosophy" (179).

Buridan was among the few medieval scholars to entertain the possibility that the earth turned on its axis. He thought that a rotating earth would have no impact on astronomical calculations and so physical arguments, rather than astronomical observations, could settle the matter. He offered a number of arguments or "persuasions" in favor of terrestrial rotation. Paraphrasing Buridan's arguments, Grant says:

"Although it appears to us that the earth on which we stand is at rest, and the sun is carried around us on its sphere, the reverse might be true, since the observed celestial phenomena would remain the same. If the earth did actually rotate, we would be unaware of its motion. The situation would be analogous to that of a person on a moving ship that passes another ship actually at rest. If the observer on the moving ship imagines himself at rest, the ship actually at rest would appear to be in motion. Similarly, if the sun were truly at rest and the earth rotated, we would perceive the opposite. On strictly astronomical grounds, Buridan believed that either hypothesis could save the celestial phenomena" (Foundations 113).

Buridan's two other arguments in support of daily axial rotation are, again in Grant's words, as follows:

"If rest is a nobler state than motion, as was often assumed, would it not be more appropriate for the nobler celestial bodies, including the sphere of the fixed stars, to remain at rest, while the earth, which was regarded as the most ignoble body in the cosmos, rotated?  Because nature was usually assumed to operate in the simplest terms, would it not be simpler, and therefore more appropriate, for the small earth to turn with the swiftest speed, while the incomparably large celestial orbs remain at rest?  Simplicity is again satisfied because the earth would need to rotate with a much smaller daily speed than the huge celestial orbs" (113).

Despite these brilliantly crafted arguments, Buridan eventually opted for the belief in an immobile earth. He reasoned, as Lindberg puts it, that "an arrow shot vertically upward (on a windless day) from the surface of a rotating earth would not return to its starting point, because while it was in the air the earth would be moving beneath it; since an arrow shot vertically upward does return to its starting point, he argued, we can be certain that the earth is stationary" (Beginnings 283). He also relied on the impetus theory to decide the matter. Grant explains:

"When the arrow is projected upward, a sufficient quantity of impetus is impressed into the arrow to enable it to resist the lateral push of the air, as the latter accompanies the earth's rotation. By resisting the lateral push of the air, the arrow should lag behind the earth and air and fall noticeably to the west of the place from which it was launched. Because this is contrary to experience, Buridan concluded that the earth is at rest" (Foundations 114).

Nicole Oresme (1325-82), Buridan's brilliant student, took up the issue of whether the earth was fixed or moving on its axis. Though he eventually ruled, as his teacher had done before him, in favor of a stationary earth, Oresme devised, in tackling the problem, solid arguments in support of earthly rotation. In response to one of Buridan's arguments, Oresme argued, in Lindberg's words, that 

"on a rotating earth, while the arrow is moving vertically upward and then vertically downward, it would also accompany the earth in its horizontal motion; the arrow would therefore remain above the point on the earth from which it was shot and return eventually to its starting point" (283).

Oresme also maintained that biblical passages appearing to support a stationary earth should not be taken literally because the biblical text "conforms to the customary usage of popular speech" (283). He further postulated that "a terrestrial rotation from west to east would contribute toward a more harmonious universe, since the earth and all celestial bodies would move in the same direction in periods that increase as we move outward from the earth" (Grant's Foundations 115). Like Buridan, Oresme invoked the simplicity argument, noting that "[t]he earth's rotation would be cosmically simpler because the earth's rotational speed would be much slower than the speeds required by the celestial orbs, which would have to be 'far beyond belief and estimation.' God would seem to have such an operation in vain" (115). 

Despite his bold and sound arguments, Oresme eventually decided, for reasons that remain unclear, to accept the fixity of the earth — a decision that has taxed the minds of historians for a long time. In any case, Oresme's and Buridan's strong arguments in support of earthly rotation were to reappear in Copernicus' defense of the heliocentric model.

Oresme's other, perhaps greatest, achievement was to provide geometrical proof and graphical depiction of the Merton Calculators' two theorems. He made a geometrical and graphical representation of the quantity and intensity of a quality (such as temperature and velocity). This analysis is considered "an obvious forerunner of modern graphing technique" (Lindberg's Beginnings 303). 

Albert of Saxony (1316-1390), a German scholar and contemporary of Buridan and Oresme, taught philosophy in Paris and later founded a university in Vienna before being appointed a bishop. Though he was not as innovative as Buridan and Oresme, Albert turned a skeptical eye to certain aspects of Aristotelian physics. While Aristotle had implied that a heavy object like a cannon ball would fall off a cliff in a straight line, Albert drew a diagram showing a cannon ball shooting out a barrel in a straight line and then curving when it reached the limit of its range — "the earliest picture we have of curved trajectory" (Hannam 186).

It would be a mistake to assume that Buridan and Oresme were the last great thinkers of the Middle Ages. The German polymath and Cardinal Nicholas of Cusa (1400-1464) showed interest in philosophy, mathematics, law, astronomy, and theology. He speculated that the universe was limitless and infinite, and relegated the status of the earth by deposing it from the center of the universe. He also posited the idea of a moving earth, and more significantly, anticipated one of Johannes Kepler's (1571-1630) laws of planetary motion by suggesting that since there were no perfect circles in the universe, the planets must have elliptical, rather than circular, orbits. Cardinal Nicholas followed the path of Grosseteste and Bradwardine in recognizing the importance of combining natural philosophy with mathematics, but he struck out in a new direction when he insisted on the need to come up with exact standards of measurement.


I shall discuss, very briefly, the status of European medicine in the medieval period. Europe did make great strides in this field, especially as a result of the reintroduction of the Greco-Arabic medical tradition from the 11th century forward. Up until that point, European medicine had been largely bound up with superstition and magic, and a whole tradition emerged that associated saints and relics with miraculous cures. Many early medieval Europeans believed that disease had divine origins and viewed sickness as divine punishment for sin. Local healers continued to practice their craft, but the disintegration of the Western Roman Empire caused a precipitous decline in the number of Western medical practitioners who were knowledgeable about Greco-Roman medicine. We should keep in mind that the rupture with the ancient medical heritage was not absolute; Western scholars did have access to a small portion of ancient medical literature, particularly some writings by Hippocrates and Galen, as well as Dioscorides' De materia medica. In the meantime, monasteries and convents served as hospitals, monks cultivated medicinal plants, and some nuns were skilled in healing. As Lindberg states, "increasingly the most hospitable settings for medical practice seem to have been the religious ones, particularly the monasteries, where care of the sick members of the community was an important obligation" (Beginnings 322). Cassiodorus, who founded a monastery at Vivarium, instructed the monks to study the available medical texts of Hippocrates, Galen, and Dioscorides. A high level of medical practice and the use of secular medical texts could be found in monastic centers such as Monte Cassino, Reichenau, and St. Gall.

What is interesting is that, while the importance of the Western monasteries in the preservation of medical knowledge should not be overlooked, those were Jewish physicians who had dominated European medicine until the medical faculties, especially at the University of Salerno, took the lead in the 13th century. The dominance of Jews in medieval medicine prompted the church to ban the employment of Jewish physicians by Christians, but these prohibitions were largely unheeded. Durant says:

"In 1246, the Council of Beziers forbade Christians to employ Jewish physicians; in 1267 the Council of Vienna forbade Jewish physicians to treat Christians. Such prohibitions did not prevent some prominent Christians from availing themselves of Jewish medical skill; Pope Boniface VIII, suffering from an eye ailment, called in Isaac ben Mordecai; Raymond Lull complained that every monastery had a Jewish physician; a papal legate was shocked that this was also the fate of many nunneries; and Christian kings of Spain employed Jewish medical care down to the reign of Ferdinand and Isabella. Sheshet Benveniste of Barcelona wrote the chief gynecological treatise of his time. The Jews lost their ascendency in the medical practice of Christendom only when Christian universities, in the thirteenth century, adopted rational medicine" (404).

The revival of European medicine started with the recovery of Greco-Arabic texts through the translation movement I have examined earlier. These medical texts constituted an essential component of instruction and study at the European medical faculties, especially in Salerno. Constantine the African, the 11th-century North African merchant and monk of Muslim origins, learned of the shortage in Latin medical material while visiting the Italian city of Salerno. He returned to North Africa, gained possession of Arabic medical texts, went back to Salerno, entered the monastery of Monte Cassino, and devoted the rest of his life to translating these texts into Latin. His output was enormous though there is disagreement over the quality of his translations. In any case, Constantine translated three works by Isaac Israeli, three works by Hippocrates (Aphorisms, Prognostica, Regimen), Hunayn ibn Ishaq's Isagoge to Galen's Tegni, Haly Abbas' Pantegni, Galen's Megategni, the Viaticum of Ibn al-Jazzar, and a few other short treatises. He thus "supplied a basic foundation of medical literature on which the West would build for several centuries" (Lindberg's "The Transmission of Greek and Arabic Learning to the West" 62). 

One particularly fascinating aspect of medieval medicine in Europe is the performance of dissection. While dissection was taboo in ancient Greece and Rome (except in Hellenistic Alexandria), European medical practitioners apparently did not encounter rigid opposition to this practice from the Catholic Church, at least from the late Middle Ages onwards. As early as the beginning of the 13th century, Pope Innocent III ordered the postmortem autopsy of a person who was suspected to have died of foul play. During the 13th and 14th centuries, Europeans were performing many dissections, especially postmortem autopsies, most of which were conducted to determine if the deceased had died of natural causes. Italian physician Mondino de' Luzzi (1265-1326) published the highly influential "Anatomy Based on Human Dissection," thus reintroducing human dissection into anatomy. At the end of the 13th century, medical specialists, especially in Bologna, had already begun dissecting human bodies as part of training their students. By the 14th century, human dissection had become part of medical training all over Europe, with textbooks on human anatomy based on dissection in wide circulation. Europeans, especially in Salerno, were also undertaking dissections of pigs as early as the 12th century. This means that anatomists in Europe had at their disposal a considerable stock of empirical knowledge about the human body. In addition to the establishment of medical faculties, the century and a half between 1200 and 1350 saw the construction of many hospitals, and this is why this period in European history has been called "the great period of hospital creation" (Huff's Rise of Early Modern Science 195). All these developments eventually culminated with the 1543 publication of Andreas Vesalius' On the Fabric of the Human Body which launched the medical revolution.

The doctors of medicine in the medical faculties were concerned about medical malpractice and this led to the enactment of statutes and regulations all over Europe, which restricted the practice of medicine to those who had been certified by a university faculty or a board of medical specialists. Beginning in the 12th century, Europeans developed "a variety of ways of evaluating and attesting to the competence" of medical practitioners (190). In addition, medical faculties, like those in Paris and Bologna, monopolized the regulation of medical education and practice. For example, the medical faculty in Bologna forbade anyone in the city from practicing medicine or performing surgery without their permission. Anyone who claimed to have studied medicine outside the city was not allowed to practice medicine within the confines of the city unless he could provide three trustworthy witnesses; he would also have to examined, licensed, and approved by the physicians of the faculties. 

Medieval University as Incubator of Science

The foundation of the university as an independent institution where the sciences were systematically taught and granted a permanent institutional base is arguably medieval Europe's most valuable and enduring legacy. There is consensus among historians on the European origins of the university system. On the uniqueness of the European university, Grant says: "The universities that had emerged by the thirteenth century in Paris, Oxford, and Bologna were different from anything the world had ever seen. Nothing in Islam, China, or India, or in the ancient civilizations of South America, was comparable to the medieval university. It is in this remarkable institution, and its unusual activities, that the foundations of modern science must be sought" (Foundations 172). It is somewhat difficult to determine when the universities were officially set up, but they are believed to have developed out of the Cathedral schools from the mid-12th century onwards. In this regard, Lindberg says the following: 

"It is impossible to assign a precise date to the founding of any of the early universities for the simple reason that they were not founded, but emerged out of preexisting schools — their charters coming out after the fact. It is customary, however, to see the masters of Bologna as having achieved university status by 1150, those of Paris by about 1200, and those of Oxford by 1220. Later universities were generally modelled on one or another of these three" (Beginnings 219).

Other universities were established at Cambridge in 1225, Padua in 1222, Toulouse in 1229, Salerno in 1250, etc.

The universities were corporate entities that enjoyed legal independence from the secular and ecclesiastical authorities. They had the right to manage their own affairs, to legislate and enact their own laws, to elect their chairmen, to buy and sell property, to have legal representation in various forums, to make contracts, etc. More importantly, the newly translated body of Greco-Arabic knowledge streaming into Europe from the Islamic world and Byzantine Empire was readily assimilated into university curriculum, and thus the study of scientific subjects, particularly Aristotle's books on natural philosophy, became deeply entrenched in university education. In other words, the study of science underwent the crucial process of institutionalization, thus ensuring its protection, persistence, and dissemination. Medieval European students took courses in astronomy, logic, geometry, arithmetic, music, and natural philosophy, in addition to the more advanced disciplines of law, medicine, and theology. On this momentous development, Grant points out: 

"For the first time in history, an institution had been created for the teaching of science, natural philosophy, and logic. Also, for the first time, an extensive four-to six-year course of study in higher education was based on a fundamentally scientific curriculum, with natural philosophy as its most important component. Even more remarkable is that these disciplines served as the core curriculum for all students and were virtual prerequisites for entry into the higher disciplines of law, medicine, and theology. They were taught on a regular basis for centuries. As universities multiplied during the thirteenth to fifteenth centuries, the same logic-science-natural philosophy curriculum was disseminated throughout Europe, extending as far east as Poland" (Foundations 172-3).

The fact students who wished to embark on theological studies were required to first attain Bachelor and Master of Arts degrees resulted in the creation of a class of theologian-natural philosophers, who had solid background not only in theology and logic but in astronomy, optics, mathematics, and other scientific disciplines. It comes as no surprise then that "some of the most noteworthy accomplishments in science and mathematics during the Middle Ages came from theologians, as the names of Albertus Magnus, Robert Grosseteste, John Pecham, Theodoric of Freiburg, Thomas Bradwardine, and Henry of Langenstein bear witness" (Grant's Foundations 175).

University scholars and masters enjoyed a host of prerogatives, including protection from the rage of the townspeople, as well as exemption from civil duties, from local taxes, and from the jurisdiction of the town in which the university was located. They also had a great degree of freedom of thought and expression and "there was almost no doctrine, philosophical or theological, that was not submitted to minute scrutiny and criticism" (Lindberg's Beginnings 224). There were of course certain theological limitations and indeed the Middle Ages did witness, from time to time, disputes between scholars and church authorities as when the bishop of Paris issued in 1277 the famous condemnations of some of Aristotle's teachings. These instances, however, should not be blown out of proportion or invoked to buttress the widely believed falsehood that the medieval church adopted a repressive posture toward free inquiry. Cases like the temporary ban on Aristotle in 13th-century Paris were local incidents and "relatively minor aberrations when viewed against the grand sweep of the history of Western Christianity" (Grant's Foundations 176). In contrast to popular belief, not only did the medieval Catholic Church not oppose science, in many cases it actively sponsored its pursuit and created an atmosphere conducive for its development and flowering. As the dominant authority in the Middle Ages, the church could have taken steps, had it wished, to ban or impose rigid constraints on science, which would have held back scientific progress, but it didn't. Instead, it accepted and even facilitated the integration of science into the university system, and in many cases had a hand in the foundation of universities across Europe. 

Works Cited

Durant, Will. The Age of Faith: A History of Medieval Civilization — Christian, Islamic, and Judaic — From Constantine to Dante: A.D. 325-1300. New York: Simon and Schuster, 1950. Print.

Freely, John. Light from the East: How the Science of Medieval Islam Helped to Shape the Western World. London: I. B. Tauris, 2015. Print.

Freeman, Charles. The Closing of the Western Mind: The Rise of Faith and the Fall of Reason. New York: Vintage Books, 2002. Print.

Grant, Edward. The Foundations of Modern Science in the Middle Ages: Their Religious, Institutional, and Intellectual Contexts. Cambridge: Cambridge University Press, 1996. Print.

Hannam, James. The Genesis of Science: How the Christian Middle Ages Launched the Scientific Revolution. Washington: Regnery Publishing, 2011. Print.

Huff, Toby. The Rise of Early Modern Science: Islam, China and the West. 2nd edition. New York: Cambridge University Press, 2003. Print.

Lindberg, C. David. The Beginnings of Western Science: The European Scientific Tradition in Philosophical, Religious, and Institutional Context, Prehistory to A.D. 1450. 2nd edition. Chicago: The University of Chicago Press, 2007. Print.

_________. "The Transmission of Greek and Arabic Learning to the West." Science in the Middle Ages, edited by David C. Lindberg, The University of Chicago Press, 1980, 52-90.

Woods E. Thomas. How the Catholic Church Built Western Civilization. Washington: Regnery History, 2012. Print.


"Medieval Science," Oxymoron?  Think Again - Part 1 of 3

"Medieval Science," Oxymoron?  Think Again - Part 2 of 3

"Medieval Science," Oxymoron?  Think Again - Part 3 of 3 




Tamer Nashef. "'Medieval Science,' Oxymoron? Think Again - Part 3 of 3." Catholic Education Resource Center (2016).

Reprinted with permisison of the author, Tamer Nashef.

The Author

Tamer Nashef is an Arab freelance researcher and translator from Israel. He holds bachelor's and master's degrees in English literature from the University of Haifa. Nashef is interested in a broad range of topics, especially Western philosophy, intellectual history of civilizations, Christian and Islamic theology with particular emphasis on the relation between science/reason and faith, and English literature. He is planning to write a book on the intellectual, scientific, and legal developments in the Middle Ages that led to the scientific Revolution and the rise of the modern world, and on the status of reason in the Catholic tradition. Nashef speaks three languages: Arabic, Hebrew, and English.

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