Message #27233

[Bianca]

Long after Aristotle had demonstrated, in the fourth century BC, that the world was a sphere, the old Babylonian image persisted. Writing almost 1400 years after Aristotle, and perfectly aware that the earth is spherical, al-Mas'udi could still compare it to an egg floating in water. The Arab historian Ibn Khaldun, writing 400 years after al-Mas'udi and almost 1900 after Aristotle, compared the inhabited portion of the world to a grape floating in a saucer of water.

The Babylonians had little knowledge of lands beyond Mesopotamia and its immediate surround­ings. Their image of the world was rooted in their cos­mology, rather than based on observation. That the Babylonians proved to be correct, in the sense that all the great bodies of water that encircle the globe are interconnected, is fortuitous. Yet it was this idea, passed on to the Greeks, then through the Arabs to medieval Europe, that contributed to the geog­raphical discoveries of the 15th and 16th centuries.

Hernando Columbus, in his biography of his father Christopher, lists the classical and medieval sources that led the admiral to think he could reach the Indies by sailing westward. One of the most important of these sources was Aristotle's De Caelo (On the Heavens), a book known in Arabic translation since the ninth century and often quoted by al-Mas'udi. The original Greek text reached Italy in the 15th century, after the fall of Constantinople in 1453, but was not printed until after the discovery of America. It had been known in Spain, however, since the 12th century through a commentary on it by Ibn Rushd of Cordova, the Averroes of the Latin Middle Ages. Whether Co­lumbus knew De Caelo through Latin translations of Averroes or more directly through the new Renais­sance translations by Italian humanists with whom he was in contact, is unknown. In any case, here is the passage that fired his imagination:

There is much change, I mean in the stars which are overhead, and the stars seen are different, as one moves northward or southward. Indeed there are some stars seen in Egypt and in the neighborhood of Cyprus which are not seen in the northerly regions; and stars which, in the north, are never beyond the range of observation, in those regions rise and set. All of which goes to show not only that the earth is circular in shape, but also that it is a sphere of no great size; for otherwise the effect of so slight a change of place would not be so quickly apparent. Hence one should not be too sure of the incredibility of the view of those who conceive that there is continuity between the parts about the Pillars of Hercules and the parts about India, and that in this way the ocean is one. As further evidence in favor of this they quote the case of elephants, a species occurring in each of these extreme regions, suggesting that the common characteristic of these extremes is explained by their continuity. Also those mathematicians who try to calculate the size of the earth's circumference arrive at the figure only that the earth's mass is spherical, but also that as compared with the stars it is not of great size. 400,000 stades. This indicates not only that the earth’s mass is spherical, but also that as compared with the stars it is not of great size.