Just a historical note: common Western belief in a flat earth is a nineteenth-century myth popularized by Washington Irving and Antoine-Jean Letronne. Since Pythagoras, to my knowledge only Lactantius (c. 245–325) and Cosmas Indicopleustes (first half of the sixth century) publicly argued that the earth is flat. Lactantius was considered a heretic for his Manichaean worldview and Cosmas did not intend his model, which was sharply criticized by his contemporary John Philoponus, to be taken literally.