These curious passages were written at some date after 1163, when Hildegard was at least 65 years old. They reveal our prophetess attempting to revise much of her earlier theory of the universe, and while seeking to justify her earlier views, endeavouring also to bring them into line with the new science that was now just beginning to reach her world. Note that (_a_) the universe has become round; (_b_) there is an attempt to arrange the zones according to their density, i.e. from without inwards, fire, air (ether), water, earth; (_c_) exact measurements are given; (_d_) the watery zone is continued earthward so as to mingle with the central circle. In all these and other respects she is joining the general current of mediaeval science then beginning to be moulded by works translated from the Arabic. Her knowledge of the movements of the heavenly bodies is entirely innocent of the doctrine of epicycles, but in other respects her views have come to resemble those, for instance, of Messahalah, one of the simplest and easiest writers on the sphere available in her day. Furthermore, her conceptions have developed so as to fit in with the macrocosm-microcosm scheme which she grasped about the year 1158. Even in her latest work, however, her theory of the universe exhibits differences from that adopted by the schoolmen, as may be seen by comparing her diagram with, for example, the scheme of Dante (Fig. 4). [Illustration: Fig. 4. DANTE’S SCHEME OF THE UNIVERSE Slightly modified from Michelangelo Caetani, duca di Sermoneta, _La materia della Divina Commedia di Dante Allighieri dichiarata in VI tavole_, Monte Cassino, 1855.] Like many mediaeval writers, Hildegard would have liked to imagine an ideal state of the elemental spheres in which the rarest, fire, was uppermost, and the densest, earth, undermost. Such a scheme was, in fact, purveyed by Bernard Sylvestris and by Messahalah. Her conceptions were however disturbed by the awkward facts that water penetrated below the earth, and indeed sought the lowest level, while air and not water lay immediately above the earth’s surface. Mediaeval writers adopted various devices and expended a great amount of ingenuity in dealing with this discrepancy, which was a constant source of obscurity and confusion. Hildegard devotes much space and some highly involved allegory both in the _Scivias_ and in the _Liber Divinorum Operum_ to the explanation of the difficulty, while Dante himself wrote a treatise in high scholastic style on this very subject.[70] [Illustration: Plate X. A CRUCIFIX IN THE UFFIZI GALLERY About the middle of the XIIIth Century.] VII. MACROCOSM AND MICROCOSM