Cosmas justifies this system by declaring that, according to the doctrine of the Fathers and the Commentators on the Bible, the earth has the form of the Tabernacle that Moses erected in the desert; which was like an oblong box, twice as long as broad. But we may find other similarities,--for this land beyond the ocean recalls the Atlantic of the ancients, and the Mahomedans, and Orientals in general, say that the earth is surrounded by a high mountain, which is a similar idea to the walls of Cosmas. [Illustration: FIG. 39.--THE COSMOGRAPHY OF COSMAS.] "God," he says, "in creating the earth, rested it on nothing. The earth is therefore sustained by the power of God, the Creator of all things, supporting all things by the word of His power. If below the earth, or outside of it, anything existed, it would fall of its own accord. So God made the earth the base of the universe, and ordained that it should sustain itself by its own proper gravity." After having made a great square box of the universe, it remained for him to explain the celestial phenomena, such as the succession of days and nights and the vicissitudes of the seasons. [Illustration: FIG. 40.--THE SQUARE EARTH.] This is the remarkable explanation he gives. He says that the earth, that is, the oblong table circumscribed on all sides by high walls, is divided into three parts; first the habitable earth, which occupies the middle; secondly, the ocean which surrounds this on all sides; and thirdly, another dry land which surrounds the ocean, terminated itself by these high walls on which the firmament rests. According to him the habitable earth is always higher as we go north, so that southern countries are always much lower than northern. For this reason, he says, the Tigris and Euphrates, which run towards the south, are much more rapid than the Nile, which runs northwards. At the extreme north there is a large conical mountain, behind which the sun, moon, planets, and comets all set. These stars never pass below the earth, they only pass behind this great mountain, which hides them for a longer or shorter time from our observation. According as the sun departs from or approaches the north, and consequently is lower or higher in the heavens, he disappears at a point nearer to or further from the base of the mountain, and so is behind it a longer or shorter time, whence the inequality of the days and nights, the vicissitudes of the seasons, eclipses, and other phenomena. This idea is not peculiar to Cosmas, for according to the Indians, the mountain of Someirat is in the centre of the earth, and when the sun appears to set, he is really only hiding behind this mountain.