The Christian cosmographers, having found in a spiritual sense a new heaven and a new earth, were at pains to create them in a scientific sense also. It was their aim to reconcile geographical theory with the literal sense of Holy Scripture, and they were not only unable to explain, but were (for the most part) willing to disprove, pre-Christian theory by that light. Thus Lactantius Firmianus (_c._ 260–340), becoming converted, denied the possibility of the sphericity of the earth or the existence of antipodes. On the other hand, this conception died hard, for it was maintained by pagan writers at this time--as, for instance, Martianus Capella, who, writing in the third or fourth century, followed such authorities as Ptolemy and Pythagoras. And these pre-Christian views must have caused some of the Christian authors to doubt, for they left unsettled such questions as that of the earth’s shape, on the plea that they formed no part of the Christian doctrine; an instance of this attitude is provided by St. Basil the Great of Cæsarea (_c._ 330–379) in his treatise on the Hexaemeron (Six Days of the Creation). [Illustration: Fig. 5.--The World according to Cosmas Indicopleustes.] One of the principal popular attractions of geography has always been its function of describing the wonders of distant lands, and in Julius Solinus Polyhistor (probably of the third century) we have a typical geographer of the marvellous, who in his _Collectanea Rerum Memorabilium_ drew upon Pliny, Pomponius Mela, and many earlier authors for a description of the wonders of the world, and became himself regarded as a high authority. With such influences at work on the study of geography, the genesis of the theories of Cosmas Indicopleustes becomes perhaps less surprising than the theories themselves. He was a merchant of Alexandria, and a traveller (as his surname is inaccurately intended to record) in the Red Sea and the ocean beyond, who, thus fortified in geographical study, became a monk and wrote his _Christian Topography_ about the middle of the sixth century, in opposition to the pre-Christian theories. Under his pen the inhabited earth became a flat, rectangular oblong surrounded by oceans. At the north is a conical mountain round which the sun (which is some forty miles in diameter and at no great distance from the earth) revolves, passing about the summit in summer, so that it is hidden from the earth for a shorter time daily than in the winter, when it passes about the base. Again, in such conditions as have been indicated, it is at least intelligible that a responsible writer should accept a mountain 250 miles high, as is stated of Mount Pelion by Dicuil, an Irish monastic scholar who completed his _De Mensura Orbis Terræ_ in 825. He, however, was little else than a compiler, and in the manner of his kind made an ill choice of sources. Among them, however, he refers to surveys made by Julius Cæsar, Augustus, and one of the emperors Theodosius;