But if the earth is a globe, there is every reason to believe in the existence of antipodes; and if there are antipodes, all cannot behold Christ coming in the clouds on the final day. To the medieval theologians, at least to the larger number of them, this argument disposed effectually of the Ptolemaic theory. Job does indeed say that God “hangeth the earth upon nothing,”[13] and this passage might point to a spherical form; but then the Psalmist affirms that He “stretched out the earth above the waters,”[14] and this statement would indicate that the inhabited part of the earth is an island floating upon the waters of the great Ocean, by which it is also surrounded. This belief was generally maintained in the earlier centuries of the classical world, and it had wide acceptance in the middle ages. There were also those who held that beyond and around the outer Ocean is a great girdle of fire. It is likely, however, that many believed with Isidore of Seville that it is useless to speculate on subjects of this sort. “Whether it [the earth] is supported by the density of the air, or whether it is spread out upon the waters ... or how the yielding air can support such a vast mass as the earth, whether such an immense weight can be upheld by the waters without being submerged, or how the earth maintains its balance ... these matters it is not permitted any mortal to know and they are not for us to discuss.”[15] Footnote 13: _Job_, xxvi, 7. Footnote 14: _Psalms_, cxxxvi, 6. Footnote 15: _De Natura Rerum Liber_, c. xlv: Migne, _Patrologia Latina_, LXXXIII, 1015. There can be no doubt that the author of the _King’s Mirror_ believed in the Ptolemaic theory of a spherical earth. In speaking of our planet he uses the term _jarðarbollr_,[16] earth-sphere. In an effort to explain why some countries are hotter than others, he suggests an experiment with an apple. It is not clear how this can shed much light on the problem, but the author boldly states the point to be illustrated: “From this you may infer that the earth-circle is round like a ball.”[17] Footnote 16: See c. xix. Footnote 17: See c. vii.