Europe’s Place in the World: Classical Geography and Its Legacy

Sources

A Round Earth. Among the great myths concerning the age of exploration, perhaps none is more powerful and durable than the widespread notion that Christopher Columbus proved to a disbelieving Europe that the earth was in fact round and spherical, not flat. In reality educated Europeans had understood that the earth was spherical for at least two millennia before Columbus’s 1492 voyage. As early as 500 b.c. the students of the mathematician Pythagoras were already speaking of the earth’s spherical shape. Evidence for the earth’s sphericity came from a variety of observations. The ancients noticed, for example, that the hull of a ship sailing away from an observer disappeared before the tip of the mast,

suggesting that the earth’s shape was curved. Similarly the ancients noted that the circular shadow cast by the earth on the surface of the moon during a lunar eclipse further supported the idea of the earth’s sphericity. The idea of the round earth was in fact so widely accepted that it became a cornerstone assumption of the cosmological system that would continue to dominate European thought for two thousand years, well into the age of exploration.

Aristotelian Worldview. The vision of the universe and the earth’s place within it that continued to shape Renaissance worldviews received its definitive formulation in the work of the ancient Greek philosopher Aristotle. Summarizing received knowledge and adding observations of his own, Aristotle outlined a theory which placed an immobile, spherical earth at the very center of a finite universe which was bounded on its outer edge by the so-called sphere of fixed stars. Nearly all of the stars which we see in the night sky were, according to Aristotle, embedded within this hollow, glasslike globe on the universe’s outer edge. This sphere of fixed stars rotated on its axis once daily, explaining the circular motion which we see as the stars move across the sky each night. Between the central earth and the stars were seven other rotating spheres into which were embedded what Aristotle called the “planets.” These included, in succession moving away from the earth: the moon, Mercury, Venus, the sun, Mars, Jupiter, and Saturn (Uranus, Neptune, and Pluto are invisible to the naked eye and were discovered only after the invention of the telescope). Until the Renaissance, Europeans accepted Aristotle’s model of the universe for two reasons. First, it effectively explained observed phenomena. Second, it had a variety of practical applications including, significantly, in the field of navigation.

Navigation. As a scientific model of the actual universe, Aristotle’s cosmology was gradually discredited as a result of the Scientific Revolution of the sixteenth and seventeenth centuries. However, as a theoretical tool it continues to be useful in many ways even today. For example, current navigation handbooks continue to base navigational practices on Aristotelian principles, and most begin with some statement such as this: “For present purposes we shall assume that the earth is a small stationary sphere whose center coincides with a much larger rotating stellar sphere.” In short whether in the time of Columbus or in our own day, navigating “by the stars” requires that the navigator make the thoroughly Aristotelian assumption that the earth is a stationary sphere at the center of a much larger sphere of fixed stars. Of particular significance to sailors in the northern hemisphere is, of course, the North Star. Because of its position at one pole of the navigator’s assumed sphere of fixed stars, the North Star does not appear to rotate circularly along with the other stars in the night sky. The navigational usefulness of the North Star lies principally in the fact that its position in the sky allows the sailor to calculate latitude. The further north one goes the higher in the sky the North Star will appear. As one moves south the North Star will appear in a lower position in the sky, nearer to the horizon. As one moves south of the equator it disappears completely from view. By 1500 European navigators sailing in waters south of the equator had identified the group of stars called the Southern Cross, the southern hemisphere’s equivalent of the North Star. Identification of the constellation allowed European sailors to determine their latitudinal position in southern waters as well. Basing their calculations on an Aristotelian vision of the universe, mariners by the time of Columbus had become quite skillful in determining latitude as they sailed the open ocean.

Eratosthenes. From the modern point of view one of the most startling achievements of ancient scientific thought comes from the Greek geographer Eratosthenes. Based upon observation and speculation Eratosthenes not only knew that the earth was spherical in shape but also provided the amazingly accurate estimate that it was 24,675 miles in circumference at the equator. (We know today that its circumference is about 24,860 miles.) By the third century b.c., then, ancient thinkers not only understood that the earth was spherical in shape but also had a remarkably accurate idea of its size. Eratosthenes also speculated that it would be possible for a ship to sail from Spain either around the southern tip of Africa or directly west across the Atlantic Ocean to reach India, predicting some 1,700 years before the fact, European voyages in the age of exploration and expansion.

Sources

Thomas Kuhn, The Copernican Revolution: Planetary Astronomy in the Development of Western Thought (Cambridge, Mass.: Harvard University Press, 1957);

John P. McKay, Bennet D. Hill, and John Buckler, A History of Western Society, fourth edition (Boston: Houghton Mifflin, 1991).