In Homer’s time (c. 800 BCE), the map of the world showed the continental mass formed by parts of Asia, Africa, and Europe surrounded by a vast body of water, Oceanus. Herodotus, however, felt that the Homeric world had too much water and not enough land. To balance things out, he replaced Oceanus with a great desert.

Symmetry was an overriding concern of the Greeks. For example, they noted that a line drawn between the Nile and the Danube would give a somewhat symmetrical version of the known world. But they obtained even more symmetry by carrying Pythagorean ideas over; that is, that Earth must be a sphere. Plato accepted this on purely geometrical grounds, but Aristotle offered a variety of proofs of sphericity from observation. Later Greek geographers accepted the spherical Earth as a matter of course and worked from there.

The Greek belief in symmetry resulted in the accidental insight that there must be a great continent in the Southern Hemisphere. Since the Greeks knew there was a great land mass in the Northern Hemisphere, they believed it must be balanced by one to the south. Pomponius Mela, writing about 43 CE, made Ceylon the northern tip of a very large Antichthones (“counterEarth”). This large continent was later known as terra australis nondum cognita (“the undiscovered southern continent”). By the 15th century, maps showed that Terra Australis had attached itself to southern Africa, effectively barring ships from reaching the East by sailing around Africa. When Bartolomeu Dias rounded the Cape of Good Hope in 1487, however, Terra Australis began to shrink.

Some maps from early in the 16th century, notably a Turkish map from 1513 and the Orantes Pinnaeus world map of 1532, show Antarctica of about the right size and location.

Even the bays and mountain ranges are close to where they are now known to be. Some people think that these were copied from truly ancient maps prepared by a seafaring people who had sailed the globe. It is more probable that among the many versions of Terra Australis, these came closest to the truth.

Another persistent tradition is that some maps before the time of Columbus and Magellan correctly located the Americas.

The Portuguese who first reached Java are supposed to have seen a map there that showed South America. The Vinland map of the Northern Hemisphere, dated at about 1440 CE, shows North America. The question of whether it is a fake is still hotly debated, with one side finding the ink right for the 15th century and another finding the ink too modern.

The discovery of the north coast of Australia by Europeans (it may have been known to the Chinese as early as the 13th century) would seem to have justified the belief in a giant southern continent, but in the mid-17th century Abel Tasman circumnavigated Australia, shrinking the southern continent once again. Even in the 18th century, however, people continued to believe in the existence of the continent at the South Pole, arguing from the same premise of symmetry as had the Greeks. Alexander Dalrymple was the particular champion of the “Great Southern Continent,” but he was passed over on the British government’s expedition to find it. Instead, the expedition was put under the leadership of Captain James Cook. While the official purpose of Cook’s voyage was to observe the transit of Venus from Tahiti, Cook also had secret orders to find the Great Southern Continent.

Cook’s first voyage (1768–71) located New Zealand, but circumnavigation showed that it was not the missing continent.

In 1772 he started out again, this time with location of the continent as his major goal. Cook reached within 75 miles of Antarctica but failed to find land. He concluded that the Great Southern Continent was either a myth or so close to the pole as to be beyond navigation. Finally, in the 19th century, various explorers reached land and the true nature of Antarctica gradually became known. The world map was finally complete on the basis of exploration, not just theoretical ideas.