People in the Middle Ages believed the Earth was flat.
Educated people in medieval Europe knew the Earth was round. The myth was popularized by 19th-century writers (notably Washington Irving) as part of a narrative pitting science against religion.
What changed?
The flat-earth Middle Ages is one of the most durable myths in the history of science, deployed in arguments about religious obscurantism and the triumph of Enlightenment reason. In schools, it served as a convenient contrast to the heroic Columbus narrative: brave empiricist versus credulous medievals. The story had obvious uses, which is why it persisted despite being demonstrably false.
Medieval European scholars knew the Earth was round. The knowledge was not esoteric or contested, it was standard. Roger Bacon discussed the spherical Earth in his Opus Majus in the thirteenth century. Thomas Aquinas referenced it as established fact. Dante's Divine Comedy is built on a cosmology with a spherical Earth at its center. Church scholars from Isidore of Seville in the seventh century to Albertus Magnus in the thirteenth accepted sphericity without apparent controversy. The Catholic Church, so often cast as the villain of flat-earth histories, never taught that the Earth was flat.
The myth was largely invented in the nineteenth century. Washington Irving's 1828 biography of Columbus dramatized a fictional confrontation between the visionary navigator and flat-earth clerics at Salamanca. John William Draper's History of the Conflict Between Religion and Science (1874) and Andrew Dickson White's A History of the Warfare of Science with Theology in Christendom (1896) formalized the narrative of religious resistance to scientific truth into what became known as the "conflict thesis." These works were enormously influential in shaping popular history.
The historian Jeffrey Burton Russell documented this invention rigorously in Inventing the Flat Earth (1991). He found that virtually every medieval scholar who commented on the subject affirmed the spherical Earth, and that the flat-earth Middle Ages was a nineteenth-century projection, not a historical description but a polemical tool.
Why does the myth survive? Because it is useful. It tells a story about ignorance and enlightenment that flatters the present. It gives the false impression that human progress has been a steady march from religious superstition toward scientific reason, when the actual history is considerably messier and more interesting.
