Wednesday, September 19, 2012

The Flat Earth Error

How many times have you heard it said that people in the Middle Ages thought the world was flat?

When I was working on The Abacus and the Cross, my biography of the Scientist Pope, I was thrilled to find a map of the world drawn shortly before the year 1000. This map appears in a standard medieval geometry textbook. It is drawn as a circle, and a caption at the top explains that the circle depicts one hemisphere of the globe. Around the edge of the circle, another caption refers to the method devised by Eratosthenes in 240 B.C. for calculating the circumference of the earth. That method was well-known to medieval scholars, who routinely referred to the earth as “round as an apple” or an egg.

This map of the spherical world from before the year 1000 is in the Staatsbibliothek Berlin (Preussicher Kulturbesitz, Phill. 1833 (Rose 138), fol. 39v). It was published in 1996 in Autour de Gerbert d’Aurillac, le Pape de l’an Mil, edited by O. Guyotjeannin and E. Poulle.

Yet in the late 1980s, historian of science Jeffrey Burton Russell, author of Inventing the Flat Earth, found the “fact” that medieval people thought the earth was flat in a 1983 textbook for fifth-graders, a 1982 text for eighth-graders, and in the 1960, 1971, and 1976 editions of the college textbook, A History of Civilization. He even found it in the bestselling 1983 book, The Discoverers, by the former Librarian of Congress, Daniel Boorstin.

Two writers share most of the blame for this: Petrarch and Washington Irving.

The Italian writer Petrarch (1304-1374) is known for two things: developing the sonnet, and coining the term “the Dark Ages.” Sometimes called the first humanist, Petrarch divided history into Ancient (before Rome became Christian in the fourth century) and Modern (his own time). Everything in between was dark. Writes Russell, “The Humanists perceived themselves as restoring ancient letters, arts, and philosophy. The more they presented themselves as heroic restorers of a glorious past, the more they had to argue that what had preceded them was a time of darkness.” (Stephen Greenblatt, in his popular book, The Swerve, is still making this argument; I’ll discuss that in a future blog post.)

The humanists also had a political motive. The Italian cities wanted to break free of the Holy Roman Empire. That meant denying all the contributions to civilization promoted by forward-thinking emperors such as Charlemagne or Ottos I, II, and III (patrons of the Scientist Pope), as well as those of the Church itself. Petrarch and his fellow humanists saw no contradiction in the fact that all of the ancient “letters, arts, and philosophy” they “discovered” had been copied, and so preserved, in the scriptoria of monasteries and cathedrals through the thousand years of the so-called darkness.

A clearly spherical earth, in the mid-14th century Bible Historiale of John the Good (BL MS Royal 19 DII).

Skip to the American writer Washington Irving (1783-1859). In his time, studying the Middle Ages was considered “a ridiculous affectation in any man who means to be useful to the present age,” according to Henry St. John Bolingbroke, whose political writings influenced Thomas Jefferson, among others.

This attitude made it easy for Washington Irving, in The Life and Voyages of Christopher Columbus, to rewrite the discovery of the New World in 1492. In the 1820s, having just published the stories “Rip Van Winkle” and “The Legend of Sleepy Hollow” to popular acclaim, Irving went to Spain, where he was given access to original documents about Columbus. Finding the truth a little “dry,” in his words, he decided his hero’s story required more dramatic tension. Writes Russell: “It was he who invented the indelible picture of the young Columbus, a ‘simple mariner,’ appearing before a dark crowd of benighted inquisitors and hooded theologians at a council of Salamanca, all of whom believed, according to Irving, that the earth was flat like a plate.”

What in fact they believed—and the original records of the council still exist—was that Columbus was fudging his numbers. Using the standard method given in medieval geometry textbooks—and on the map from before the year 1000—the Council of Salamanca calculated the circumference of the earth to be about 20,000 miles (it is actually about 25,000 miles) and the distance between one degree of latitude or longitude at the equator to be 56 2/3 miles (it is actually 68 miles). Columbus thought the earth was much smaller. He said a degree was 45 miles and the span of ocean between the Canary Islands and Japan only 2,765 miles—twenty percent of the actual figure. If he had not providentially bumped into America, Columbus would—as the experts in Salamanca believed—have run out of food and fresh water long before he reached Japan. Columbus, says Russell, had “political ability, stubborn determination, and courage” on his side. His opponents had “science and reason” on theirs.

Washington Irving took science and reason and gave them to Columbus—and it was Irving’s version of history that became common knowledge. Why? Americans, says Russell, “wanted to believe that before the dawn of America broke, the world had been in darkness.”

You can see more medieval images of a round world on Donna Seger’s blog, Streets of Salem: She writes (sadly): “every year I poll the incoming freshmen in my World History class about what they were taught in primary and secondary school and every year more than half of them raise their hands in support of the medieval flat earth.”

Join me again next Wednesday at for another writing adventure in Iceland or the medieval world.


  1. THANK YOU. It's so irritating to see this myth still having life! Not only did Dante (died 1321) know the earth was round, he understood the basics of gravity and knew that if you go to the other side of the globe, you'll feel right-side up even though you're upside-down compared to where you used to be. Nice discussion here:

  2. Hello Nancy, Thanks for the link and for you own article-- Maybe if we all keep writing the flat earth myth will be history!