Flattening the Earth

Sep-Oct 2002, Mercury Magazine, pp. 34-38.

by Jeffrey Burton Russell

Contrary to popular folklore, medieval Europeans knew Earth was a sphere, and, with the notable exception of Christopher Columbus, most had a pretty good idea of its true size.

One of the few things that everybody "knows" about medieval Europe is that people thought Earth was fiat. The cliché that Columbus discovered that Earth is round is taught so frequently in American grade schools that it has become ingrained in our consciousness.

But for nearly 80 years historians have demonstrated that medieval Europeans knew Earth to be spherical. In fact, virtually no educated person in the Middle Ages (roughly defined as 500-1500 AD.) believed Earth was fiat. The evidence is as overwhelming as historical evidence can be. German historian Reinhard Krueger and other modern scholars have identified about 100 medieval writings dealing with Earth's shape. Five seem to assert flatness, and two are ambiguous. The rest take the globe for granted. The Columbus cliché is a Flat Error popularized by the American writer Washington Irving.

Some uneducated medieval Europeans may have assumed a flat Earth, if they thought about it at all. Since almost all uneducated Europeans in the Middle Ages lived restricted lives in small regions, they had little interest in geography. But a reasonable number of medieval Europeans were educated, literate, and numerate. Many had a passing knowledge of astronomy (not astrology) and logic.

Even among educated people, interest in the shape of Earth was not high, but they would have heard that it was a globe and hardly anyone is known to have disputed this. Interest in geography in the Middle Ages was mainly practical or theoretical.Travelers wanted a road map or sea chart showing how to get from Oxford to York, say, or from Lisbon to Genoa. Many such medieval maps of land and sea exist, but they are only a little more relevant to the question of Earth's shape than a street map of Seattle is to Stephen Hawking's universe. Additionally, philosophers and theologians wanted to know what God's universe looked like and how it functioned (the same desire that eventually sparked the great expansion of science in the 17th century). Some of these philosophers were interested in describing the globe scientifically, both the parts and the whole.

Cosmology was certainly geocentric before Copernicus (1473-1543), but geocentricity and sphericity are two entirely different issues, both scientifically and historically. Educated medieval people assumed that Earth ssas the shape of a globe, just as they assumed that Earth did not rotate and was the center of ss hat see now call the solar system.

Medieval theologians had no trouble reconciling a globe with the Bible. The Bible proclaims neither a flat nor a spherical Earth. Thus, there seas no "biblical concept" of Earth's shape for medieval scholars to either accept or reject. Furthermore, medieval thinkers, unlike some modern writers, knew when to take the Bible metaphorically rather than literally. Metaphorically is hose they took the few, differing, and highly ambiguous biblical references that may suggest a flat Earth (see "Flat Earth in the Bible:' page 38).

[German cartographer Martin Behain'created this terrestrial globe in 1492 - several months before Columbus's discovery of the New World. This globe alone disproves the common misconception that medieval Europeans thought Earth was flat. The globe is housed at the Bibliotheque Nationale, Paris, France. Courtesy of Giraudon/Art Resource, New York.]
Despite the evidence that extremely few educated medieval people thought Earth was flat, the Flat Error continues to be widespread and repeated in grade schools and popularized accounts based on biased and outdated sources. Clearly, the main points of evidence need restating.

MEDIEVAL MAPS
First, no medieval European ever thought of the heavens as anything but spherical. As for Earth, the medieval term for "the world:' in the sense of "the entire Earth," was orbis terrarum ("the globe of lands"). Three-dimensional artworks indicate that Earth is round. For example, paintings depict medieval rulers carrying orbs (symbols of power) surmounted by crosses. Medieval astronomers and geographers are not known for the breakthroughs characteristic of the 17th century, but they refined and improved the Greek and Roman view of Earth as a globe, a view completely dominant after the 4th century B.C.E. Numerous medieval treatises Dc sphaera, "About the Sphere." demonstrate their knowledge and interest in the globe. German cartographer Martin Behaim even made a globe in 1492, before Columbus's voyage.

Of course, ordinary navigators in the Middle Ages would have wrecked their ships trying to sail very far on a flat Earth. They knew that boats disappeared from sight behind the horizon as they sailed outward and appeared at the horizon when returning. They knew that different stars were visible at different latitudes. They had calculated latitudes, as opposed to the much more difficult longitudes. They had also observed Earth's curved shadow on the Moon during lunar eclipses.

Many medieval maps survive, and although their details are often crude and inaccurate by modern standards, the calculations of medieval geographers and astronomers indicate how medieval scientists and philosophers viewed Earth and its dimensions. Many variants existed, but Earth was typically a globe at the center of the universe, around which the spheres of the Sun, Moon, planets, and stars revolve.

Schematically, a medieval map can be divided, like any globe or ball, into four quarters. The Eurasian-African landmass was set in the sea of one of these four quarters. The other three quarters may be entirely sea or may contain landmasses. If they have landmasses, the breadth of the ocean is so great that passage between them is impossible. If they do not have landmasses, then the sea runs west all the way from Portugal to Japan. Earth's globe is divided into climatic zones: the Arctic and Antarctic circles are mapped, as are the tropics of Cancer and Capricorn. Inhabitants of any of the quarters would meet at the center if they could descend to the center of Earth. The quarter diametrically opposite the Eurasian-African landmass is called the antipodes (meaning "opposite feet").
Both medieval and modern writers have been confused by the notion of the antipodes. The Latin term antipodes can refer either to the region or to its inhabitants. In the 8th century, Saint Boniface reproached a monk named Vergil of Salzburg for believing in the existence of antipodes. But Boniface was not rejecting the spherical shape of Earth, as many writers in the 18th through the 20th century contended. He was rejecting the idea that antipodeans, inhabitants of the antipodes, existed. Boniface believed that an impassable ocean stood between all humans (who were descendants of Adam and Eve in the Middle East) and lands beyond the oceans. Boniface's blunder is not so startling as that of 19th- and early 20th-century historians who professed themselves superior to the 8thcentury writer yet fell into a similar confusion and argued that Boniface objected to sphericity. The incident between Boniface and Vergil thus became a classic touchstone for the flat Earth misconception.

Medieval tripartite maps are another source of confusion. These maps show a two-dimensional surface with Earth divided into three parts: Asia (one half), Europe (one quarter), and Africa (one quarter). These maps represent the quarter of Earth that was believed to be inhabited, not the whole Earth. Jerusalem sometimes appears at the center of these maps, leading historians to falsely assume that medieval people believed that Earth was a flat disk centered on lerusalem. But these maps were intended to illustrate Jerusalem as the spiritual and moral center of Earth; they were not meant to he taken in a literal, geographical sense.

COLUMBUS'S DUMB LUCK
Medieval people not only understand the shape of Earth; some of them came extremely close to estimating its circumference. One school worked on refining Eratosthenes' figure of 250,000 stades, which was within 15% of the modern figure of 40,074 kilometers. The other school worked on refining Ptolemy's figure of 180,000 stades. Eratosthenes' view dominated. That school assumed that an unbroken ocean ran from the Azores and Canaries to Japan. This ocean would be an impassible obstacle for a westward voyage to the Indies. But toward the end of the Middle Ages, some 'writers revived and preferred Ptolemy's figures. The differences led to bizarre calculations by Columbus, whose determination to promote Christianity and trade (in addition to his own wealth and reputation) led him into a showdown with those who thought he could not succeed.

The arguments of Columbus's opponents in the 1480s and 1490s had mostly to do with the circumference of the globe and the width of the ocean, and nothing whatsoever to do with the shape of Earth. Some entertained the fear of sailing of the edgeof Earth. Rather, Columbus's opponents argued that the ocean was too vast for a ship to sail west to Asia without the entire crew perishing of thirst and starvation, a dangerous gamble on which to risk life - and the royal treasury. It was quite a reasonable argument, and Columbus had to work hard to overcome it. He accomplished this by scientific legerdemain, political luck, and something nobody expected.

First, Columbus adopted Ptolemy's smaller Earth against Eratosthenes' larger and more correct Earth. Next, he chose an argument by the 4th-century theologian and politician Pierre D'Ailly that the Eurasian landmass, rather than occupying only a half of the Northern Hemisphere (180°), actually occupied 225° (versus 135° for the sea. He then argued that Marco Polo's travels showed that the landmass stretched 28° more, and that Japan lay 30° east of China, reducing the ocean to 77°. Next, he subtracted 9° of sea because he planned to depart from the Canaries rather than from Spain or Portugal. Now, he was up to 292° of land versus 68° of sea. He decided that D'Ailly's original estimate for Eurasia was 8° too small, and voila, Columbus ended up with 3000 of land versus 60° of sea. Finally, Columbus switched from Arabic miles to shorter Roman miles. He audaciously concluded a figure for the sea's width equal to about 4,450 kilometers, about one fifth the actual distance between Portugal and Japan of about 22,000 kilometers.

Not many believed such preposterous calculations. But Columbus was in political luck. The Portuguese were exploring and developing the coasts of Africa, the Portuguese and Spaniards were locked in commercial and political rivalry, the Spaniards had just defeated the Muslims in Spain and expelled the Jews, and now they were eyeing new ways to expand their wealth and power. So King Ferdinand and Queen Isabella of Spain approved the crazy adventure, and in 1492 Columbus set sail across the Atlantic.

Then came one of the greatest pieces of luck in human history: on October 12, 1492, Columbus blundered into the Americas under the mistaken impression that he was encountering the East Indies. Otherwise, he and his crew would surely have perished at sea as the scholars had predicted. Columbus went to his grave believing he had traveled to the Far East.

[Washington Irving authored a highly fictionalized 19th-century biography of Christopher Columbus that fooled readers into believing that Columbus proved Earth was round. Irving and his book's title page are shown above. Courtesy of Jeffrey Burton Russell.]

THE ERROR'S ORIGIN
When and why was the Flat Error invented, and why is it generally believed today? Copernicus was certainly not to blame. When he condemned the geocentric opponents of the heliocentric system as being as wrongheaded as those who once asserted that Earth was flat, he could cite only the one flat-earther that he knew of. Lactantius, who was, as Copernicus said, "hardly an astronomer:' Neither Copernicus nor Galileo had to contend with a single flat-earther anywhere.
Oblique hints of the Flat Error exist as early as the late I 500s and early 1600s in works by Thomas Hobbes, Thomas Campanella, Francis Bacon, Heribert
Rosweide, and Bernard de Montfaucon. The earliest flat-out Flat Error I have found so far is in a book published in 1708 by John Wilkins, a scientifically inclined English clergyman. Thomas Jefferson mentioned it in an offhand manner in his 1787 Notes on the State of Virginia. The influential revolutionary propagandist Thomas Paine promoted the error at the end of the 18th century. Paine mocked those who "continued to believe for several centuries (and that in contradiction to the discoveries of philosophers and the experience of navigators), that the earth was flat like a trencher, and that a man might walk to the end of it." But there were no such people. Paine's mention of Vergil indicates that he was drawing upon an earlier source: "Vigilius [sic] was condemned to be burned for asserting the antipodes, or in other words that the earth was a globe:' Vergil, by the way, was not burned, condemned, or even formally censured.

What happened to the Flat Error after 1794, when Paine's book was published, is fairly clear, it was mentioned by a few writers and then was popularized in France by Antoine-Jean Letronne and in the English speaking world by Washington Irving. Irving was the author of the beloved Headless Horseman and of a number of fraudulent and heavily fictionalized histories of New York City, George Washington, and Christopher Columbus. Irving invented the still widely believed melodrama of Columbus, a lone hero of science, standing against the bigoted and ignorant courtiers and clergy of the Council of Salamanca, who told him the world was flat. Irving's account of this nonexistent council is fiction, but the fiction caught on with those wishing a handy stick with which to beat the Catholic Church and the "ancients:' After all, we always like to believe that earlier people were stupider than we are. For example, some of our contemporaries believe that Egyptians must have been too primitive to have built the pyramids by themselves, so they must have had help from extraterrestrials.

The silliness would probably have faded away but for the appearance of something else no one expected: the theory of evolution. In the early 19th century, the notion of slow geological change gained strength, and by mid-century Charles Darwin and Alfred Russel Wallace introduced the idea of biological evolution. Scientific doubts raised at the time are perfectly understandable in the context of the age. But other objections came from Christians who insisted on taking the entire Bible literally, which medieval Christians had not done. These antiDarwinists assumed that the creation story in Genesis was supposed to be a literal, scientific, and physical account of the beginning of the world, and because they believed the Bible to be without error, they had to reject evolution. Evolution's supporters, who apparently believed Irving's tale, claimed that evolution's opponents were just as stupid as medieval Europeans who allegedly thought Earth was flat. From there, the Flat Error found its way into textbooks, stories, and even a few encyclopedias, where it fit so nicely into what else we know most of it false about the Middle Ages.

As astronomer Steven N. Shore of Indiana University, South Bend, observed, "Facts are only the raw material of history:' And when scientists and historians get the basic facts wrong or fail to correct the record, the finished product is as distorted as a flat Earth.

JEFFREY BURTON RUSSELL is Professor of History Emeritus at the University of California, Santa Barbara. He is the author of Inventing the Flat Earth and numerous other books and articles on history, religion, and science.

One has to look long and hard to find biblical passages that refer to the shape of Earth. The only two passages to be found that do so are quite vague, explaining why it was easy for medieval Christians to accept that Earth was a globe.

Isaiah 40.22

He sits enthroned above the circle of the earth, and its people are like grasshoppers.

He stretches out the heavens like a canopy, and spreads them out like a tent to live in.

Revelation 7.1
After this I saw four angels standing at the four corners of the earth, holding back the four winds of the earth to prevent any wind from blowing on the land or on the sea or on any tree.