In the ancient Arabian chronicle of Tabari is a system founded on the earth being the solid foundation of all things; we read: "The prophet says, the all-powerful and inimitable Deity has created the mountain of Kaf round about the earth; it has been called the foundation pile of the earth, as it is said in the Koran, 'The mountains are the piles.' This world is in the midst of the mountain of Kaf, just as the finger is in the midst of the ring. This mountain is emerald, and blue in colour; no man can go to it, because he would have to pass four months in darkness to do so. There is in that mountain neither sun, nor moon, nor stars; it is so blue that the azure colour you see in the heavens comes from the brilliancy of the mountain of Kaf, which is reflected in the sky. If this were not so the sky would not be blue. All the mountains that you see are supported by Kaf; if it did not exist, all the earth would be in a continual tremble, and not a creature could live upon its surface. The heavens rest upon it like a tent." Another Arabian author, Benakaty, writing in 1317, says: "Know that the earth has the form of a globe suspended in the centre of the heavens. It is divided by the two great circles of the meridian and equator, which cut each other at light angles, into four equal parts, namely, those of the north-west, north-east, south-west, and south-east. The inhabited portion of the earth is situated in the southern hemisphere, of which one half is inhabited." Ibn-Wardy, who lived in the same century, adopted the idea of the ocean surrounding all the earth, and said we knew neither its depth nor its extent. This ocean was also acknowledged by the author of the Kaf mountain; he says it lies between the earth and that mountain, and calls it Bahr-al-Mohith. The end of the fifteenth century saw the dawn of a new era in knowledge and science. The discoveries of Columbus changed entirely the aspect of matters, the imagination was excited to fresh enterprises, and the hardihood of the adventurers through good or bad success was such as want of liberty could not destroy. Nevertheless, as we have seen, Columbus imagined the earth to have the shape of a pear. Not that he obtained this idea from his own observations, but rather retained it as a relic of past traditions. It is probable that it really dates from the seventh century. We may read in several cosmographical manuscripts of that epoch, that the earth has the form of a cone or a top, its surface rising from south to north. These ideas were considerably spread by the compilations of John of Beauvais in 1479, from whom probably Columbus derived his notion.