Medieval scholars knew the Earth was round. The flat-Earth story is the myth.
You may have learned that Columbus had to convince people the world wasn't flat. He didn't. Educated Europeans had known Earth was a sphere since ancient Greece. The idea that the Middle Ages believed in a flat Earth was largely spread in the 19th century, partly by a romanticised biography of Columbus.
Greek thinkers were describing a spherical Earth by the fifth century BC, and around 240 BC Eratosthenes calculated its circumference. That knowledge never disappeared. By the early Middle Ages most European and Middle Eastern scholars accepted a round Earth, and from about 1300 onward belief in a flat one among educated Europeans was almost non-existent. Historians David Lindberg and Ronald Numbers note that hardly any Christian scholar of the period failed to acknowledge Earth's sphericity, and many knew its approximate size.
So where did the myth come from? Accusations of flat-Earth belief were already being used in the 17th century to discredit rival authorities, including in Protestant attacks on Catholic teaching. The big push came later. In 1828 Washington Irving published a highly romanticised biography of Columbus, widely mistaken for serious scholarship, which invented a scene where ignorant churchmen objected to his claim that the Earth was round. In reality, the argument in the 1490s was about the Earth's size and how far away Asia lay, and Columbus was the one who got it wrong: his estimate of the planet's circumference was about 25 per cent too small.
Later in the 19th century, books by John William Draper (1874) and Andrew Dickson White (1896) presented history as an eternal war between science and religion, and the flat-Earth tale suited that story. The historian Jeffrey Burton Russell argues that the error flourished most between 1870 and 1920, amid the bitter debates over evolution. Stephen Jay Gould put it bluntly: there never was a period of 'flat Earth darkness' among scholars.
Although historians have refuted it since at least 1920, the myth persisted in popular culture and even textbooks. A 2009 survey found it in most history schoolbooks in Germany and Austria. It is a useful reminder that 'people in the past were foolish' is itself a story someone chose to tell.
Source: Wikipedia — Myth of the flat Earth · Text summarised from Wikipedia (CC BY-SA 4.0)
