Popular culture likes to dismiss the Middle Ages as a period of ignorance, epitomised by the supposition that everybody thought the earth was flat. Many school textbooks still hold this outdated belief. The idea that people of the Middle Ages thought that the earth was flat is completely false. That the earth was round was general knowledge all the way back to Classical Greece.
Pythagoras, all the way back to the 6th century BC, believed in a round earth. The great philosopher and scientist, Aristotle, was a round-earther. The Hellenistic scientist of the 3rd century BC, Eratosthenes, actually calculated the circumference of the earth by measuring the angle of the sun in different locations. The really impressive bit is that he calculated it within 10% of today’s accepted figure. By the time the Middle Ages rolled along the Greeks had not only posited a round earth but had calculated its circumference with astounding precision for the time.
Now, another myth is that the Medieval Catholic Church was so dismissive of Greek learning that they never would have allowed anyone to accept any ideas of the “pagans”. In fact, the Church was interested in finding truth wherever it could and in integrating it with itself. Scholastic philosophy, exemplified by St. Thomas Aquinas, was very interested in extracting truth from the Classical world and injecting it with Christian doctrine. Thomas Aquinas wanted to show that the teachings of Aristotle and the teachings of the Church were compatible. His proofs for the existence of God were based on Aristotelian principles. St. Justin Martyr even compared Socrates with Christ in his first apology. Many other great Catholic scholars were favorable to Classical knowledge, including St. Jerome, St. Ambrose of Milan, Origen, Minucius Felix, and more. Interestingly, Christians who rejected Classical thought fell into heresy themselves, such as Tertullian and Hippolytus, both Rigorists. The Catholic Church was not dismissive of Greek knowledge and learning, it wanted to embrace as much of it as it could.
There were very few major figures that believed the earth was flat. There were two people that had this belief in the Middle Ages, and are cited as proof that this was the prevailing opinion. Lactantius, a 3rd-4th century converted pagan and Christian heretic; and Cosmas Indicopleustes, a 6th century Greek geographer. These figures were not influential, and were at odds with the belief of the time. Lactantius was anxious to disprove all pagan beliefs (as he was a recent convert) which included the theory of a round earth. Cosmas Indicopleustes made a model of the universe that showed the earth as flat, and was criticized by contemporary Christian thinkers. His influence was also small because he wrote in Greek, which had been largely forgotten at the time.
The fear among potential sponsors that Christopher Columbus would sail off the edge of the world did not exist. The real fear was that he had estimated the circumference of the world at one-third of the figure Eratosthenes had calculated, and would die of starvation before he would reach India. In truth, the existence of the Americas saved Columbus and his crew from death.
The idea that people believed the earth was flat in the Middle Ages is not at all true. Of course, there may have been some people who had this belief, just as there are some odd people even today who believe the earth is flat, but it was hardly the prevailing opinion in those days. The Greeks had already calculated the earth’s circumference in the 3rd century BC, and the Catholic Church was not at all close-minded to the ideas of the Classical Greeks, epitomised in the writings of St. Thomas Aquinas. The people of the Middle Ages were not ignorant barbarians, nor were they dismissive to the ideas of the great civilizations that preceded them.