The Flat Earth Myth: What Medieval People Really Believed

Many of us learned a tidy story in school: in the Middle Ages, people believed the Earth was flat, and sailors feared falling off the edge until Columbus proved them wrong. It is a satisfying tale about brave reason defeating superstition.

It is also mostly false. Educated Europeans in the Middle Ages knew perfectly well that the Earth is a sphere. The flat-Earth Middle Ages is largely a 19th-century invention, and the way it was invented is a lesson in how history gets rewritten.

This guide looks at what medieval writers actually said, the genuine exceptions, and the writers who spread the myth.

The Greeks settled the shape long before the Middle Ages

The idea of a round Earth was old news by the medieval period. Historian Jeffrey Burton Russell, professor emeritus at the University of California, Santa Barbara, and author of Inventing the Flat Earth, summarized the ancient record in a 1997 paper: a round Earth appears at least as early as the sixth century BC with Pythagoras, followed by Aristotle, Euclid and Aristarchus, among others.

The Greeks did not just assert it; they measured it. NASA describes how, in approximately 200 BC, Eratosthenes is said to have observed sunlight shining straight down a well at noon on the solstice near modern Aswan, in Egypt. By comparing shadow lengths there and in Alexandria, along with the distance between the two cities, he calculated a rough early estimate of Earth's circumference, adding further evidence that the Earth is a sphere.

Russell's verdict is blunt: "with extraordinary few exceptions no educated person in the history of Western Civilization from the third century B.C. onward believed that the earth was flat."

What medieval writers actually said

The medieval record backs him up, and some of the clearest evidence comes from a source that might surprise you: the very author most responsible for spreading the conflict story.

In his History of the Warfare of Science with Theology in Christendom, whose preface ends with a postscript dated August 1895, Andrew Dickson White wrote that the idea of the Earth's sphericity "still lived" through the early Middle Ages. He credited Isidore of Seville and, in the eighth century, the northern European churchman Bede with upholding it, and he listed later authorities, "Albert the Great, St. Thomas Aquinas, Dante, and Vincent of Beauvais," as accepting "the doctrine of the earth's sphericity." White framed this as a long struggle against Church theology, but his own list shows how mainstream a round Earth was among medieval thinkers.

Popular writing assumed it too. The Travels of Sir John Mandeville, a fourteenth-century travel book originally written in French, survives in several medieval English versions; the 1900 edition prints the Cotton manuscript version in modern spelling, and its editor notes that the book enjoyed great popularity in England and the rest of Europe from its first printing in 1499. In that English version, one chapter sets out to show "that the land and the sea be of round shape and form." Its argument is the same one sailors could check for themselves: the northern Pole Star cannot be seen in far southern lands, where a different southern star guides ships instead. The book goes further, arguing that if ships could find the passages, "men might go by ship all about the world and above and beneath."

The real exceptions

The myth did not come from nowhere. A handful of early Christian writers did reject a spherical Earth.

Russell counts them: "at least two and at most five" early Church fathers denied it by reading biblical passages, such as Psalm 104, as geography rather than metaphor. White names Lactantius among them, and he describes the sixth-century writer Cosmas Indicopleustes, who taught that the Earth is "a parallelogram, flat, and surrounded by four seas," enclosed by walls that hold up the sky.

This is where White and Russell disagree sharply. White claimed that "the great majority of the early fathers" had tried to crush the round-Earth idea. Russell counters that tens of thousands of Christian theologians, poets, artists and scientists took the spherical view throughout the early, medieval and modern church, and that historians of science, including Edward Grant and David Lindberg, have been making this point for decades. Russell's reading draws on the historians of science he cites, and it is the one this guide follows: the flat-Earth writers were real but marginal.

A map that looks flat but is not a survey

Part of the confusion comes from medieval maps. The Library of Congress explains that the so-called T-O map, a design originally drawn in the seventh century to illustrate Isidore of Seville's encyclopedia of world knowledge, was symbolic. The "T" represented a Christian cross that placed Jerusalem at the center and divided the known continents of Asia, Europe and Africa. The "O" around it represented the medieval idea of the world surrounded by water.

A diagram like this was not trying to show the planet's three-dimensional shape, any more than a subway map tries to show the real curves of the tracks. Reading it as proof of flat-Earth belief mistakes a symbol for a survey.

How the myth was invented

If medieval people did not believe in a flat Earth, where did the story come from? Russell traced it carefully and concluded: "No one before the 1830s believed that medieval people thought that the earth was flat."

He identifies two early sources working at about the same time. One was the French scholar Antoine-Jean Letronne (1787 to 1848), who, Russell argues, misrepresented the Church fathers and their medieval successors as flat-Earthers in an 1834 work on the cosmographical ideas of the Church fathers. The other was the American writer Washington Irving, whose 1828 history of Christopher Columbus invented the scene of Columbus facing a council of hooded theologians at Salamanca who supposedly believed the Earth was flat. Russell notes that there was a real meeting at Salamanca in 1491, but quotes a modern historian of Columbus who called Irving's version "pure moonshine."

The story then spread through a larger narrative of eternal war between science and religion. Russell names the historian John Draper (1811 to 1882) and his followers, including Andrew Dickson White, the president of Cornell University. By as early as the 1860s, according to Russell, the flat-Earth tale was being taught in schools and schoolbooks as fact.

Russell also offers a view on motive: that the myth served as ammunition in the 19th-century debates over evolution. That is his interpretation, stated in a short and openly polemical paper. His documentary finding, that he could not trace the flat-Earth Middle Ages any earlier than Irving and Letronne, can be weighed separately from his view of why it caught on.

Why this myth matters

The flat-Earth story is a warning about a particular kind of historical error: projecting a modern argument onto the past. Once someone decides the past must have been ignorant, every symbolic map and every odd quotation can be made to fit, while the large body of ordinary evidence goes unread.

A few habits help guard against it:

• Read what people at the time actually wrote, not only what later writers say they believed.
• Ask how typical a quoted source was. A handful of dissenters does not define an era.
• Check when a story first appears. A claim about the 1400s that surfaces only in the 1800s deserves suspicion.
• Notice when a story serves a larger argument its author is making.

Key takeaways

• Educated people in the ancient and medieval West overwhelmingly accepted that the Earth is round, and Eratosthenes estimated its circumference around 200 BC.
• Medieval writers from Bede to Aquinas, and popular books like Mandeville's Travels, treated a spherical Earth as normal.
• A few early Christian writers, such as Lactantius and Cosmas Indicopleustes, did argue for a flat Earth, but historians regard them as exceptions.
• Medieval T-O maps were symbolic diagrams, not attempts to show the planet's shape.
• According to historian Jeffrey Burton Russell, the flat-Earth Middle Ages was invented around 1828 to 1834 by Washington Irving and Antoine-Jean Letronne, then spread by Draper and White.

Sources

• Jeffrey Burton Russell, The Myth of the Flat Earth, paper for the American Scientific Affiliation (August 4, 1997)
• NASA Science, Tropical Solstice Shadows (Night Sky Network)
• Library of Congress, Documenting New Knowledge, Exploring the Early Americas exhibition
• Andrew Dickson White, History of the Warfare of Science with Theology in Christendom, Project Gutenberg
• The Travels of Sir John Mandeville (1900 Macmillan edition), Project Gutenberg