“Medieval people believed the Earth was flat.”

The notion that people in medieval Europe widely believed the Earth was flat is a persistent historical error. This misconception largely originated in the 19th century, propagated by influential writers like Washington Irving, John William Draper, and Andrew Dickson White. Irving's romanticized 1828 biography of Christopher Columbus, for instance, inaccurately depicted Columbus as a lone visionary battling a church establishment convinced of a flat Earth. Later, Draper and White, writing about the perceived conflict between science and religion, used the "flat Earth" as a convenient symbol to portray the Middle (Review) Ages as a time of ignorance and superstition, contrasting it with the enlightenment of their own era.

In reality, educated people and scholars throughout the Middle Ages, from approximately the 5th to the 15th centuries, understood the Earth to be spherical. This knowledge was directly inherited from ancient Greek astronomers such as Aristotle and Eratosthenes, who had provided compelling proofs centuries earlier. Aristotle, in the 4th century BCE, observed that ships disappear hull-first over the horizon and that the Earth casts a round shadow on the moon during lunar eclipses, clear indicators of a spherical shape. Medieval texts, including the widely used 13th-century astronomy (Deals) textbook "De sphaera mundi" by Johannes de Sacrobosco, explicitly taught Earth's roundness. Many contemporary maps and art, such as the globus cruciger held by royalty, also depicted a spherical world.

The endurance of this myth stems from several factors. Beyond the 19th-century "warfare thesis" that sought to discredit earlier eras and religion, the narrative of Columbus proving the Earth was round made for a dramatic and inspiring story of scientific triumph over dogmatic ignorance. This compelling, though false, tale was widely adopted in educational materials, solidifying the misconception in public consciousness. However, historical evidence consistently shows that the debate surrounding Columbus's voyage was not about the Earth's shape, but rather its circumference and the feasibility of reaching Asia by sailing west.