Those who wished to have everything as complete as possible combined the system of Ptolemy with that of the Fathers of the Church, and placed in the centre of the earth the infernal regions which they surrounded by a circle. Another circle marked the earth itself, and after that the surrounding ocean, marked as water, then the circle of air, and lastly that of fire. Enveloping these, and following one after the other, were the seven circles of the seven planets; the eighth represented the sphere of the fixed stars on the firmament, then came the ninth heaven, then a tenth, the _coelum cristallinum_, and lastly an eleventh and outermost, which was the empyreal heaven, where dwelt the cherubim and seraphim, and above all the spheres was a throne on which sat the Father, as Jupiter Olympus. The others who wished for more simplicity, represented the earth in the centre of the universe, with a circle to indicate the ocean, the second sphere was that of the moon; the third was that of the sun; on the fourth were placed the four planets, Jupiter, Mars, Venus and Mercury; there was a fifth for the space outside the planets, and the last outside one was the firmament; altogether seven spheres instead of eleven. As a specimen of the style of representation of the astronomical systems of the middle ages, we may take the figure on the following page:-- Here we see the earth placed immovable in the centre of the universe, and represented by a disc traversed by the Mediterranean, and surrounded by the ocean. Round this are circumscribed the celestial spheres. That of the moon first, then that of Mercury, in which several constellations, as the Lyre, Cassiopeia, the Crown, and others, are roughly indicated, then comes the sphere of Venus with Sagittarius and the Swan. After this comes the _celestis_ _paradisus_, and the legend that, "the paradise to which Paul was raised is in this third locality; some of these must reach to us, since in them repose the souls of the prophets." In the other circles are yet other constellations: for example Pegasus, Andromeda, the Dog, Argo, the He-goat, Aquarius, the Fishes, and Canopus, figured by a star of the first magnitude. To the north is seen near the constellation of the Swan a large star with seven rays, meant to represent the brightest of those which compose the Great Bear. The stars of Cassiopeia are not only misplaced, but roughly represented. The Lyre is curiously drawn. The positions of the constellations just named are all wrong in this figure, just as we find those of towns in maps of the earth. The cartographers of the middle ages, with incredible ignorance, misplaced in general every locality. They did the same for the constellations in the celestial hemispheres. In the heaven of Jupiter, and in that of Saturn we read the words--Seraphim, Dominationes, Potestates, Archangeli, Virtutes coelorum, Principatus, Throni, Cherubim, all derived from their theology.