The Roman Empire will henceforth form the centre from which to regard any additions to geographical knowledge.  As we shall see, part of the knowledge acquired by the Romans was lost in the Dark Ages succeeding the break-up of the empire; but for our purposes this may be neglected and geographical discovery in the succeeding chapters may be roughly taken to be additions and corrections of the knowledge summed up by Claudius Ptolemy.

CHAPTER III

GEOGRAPHY IN THE DARK AGES

We have seen how, by a slow process of conquest and expansion, the ancient world got to know a large part of the Eastern Hemisphere, and how this knowledge was summed up in the great work of Claudius Ptolemy.  We have now to learn how much of this knowledge was lost or perverted—­how geography, for a time, lost the character of a science, and became once more the subject of mythical fancies similar to those which we found in its earliest stages.  Instead of knowledge which, if not quite exact, was at any rate approximately measured, the mediaeval teachers who concerned themselves with the configuration of the inhabited world substituted their own ideas of what ought to be.[1] This is a process which applies not alone to geography, but to all branches of knowledge, which, after the fall of the Roman Empire, ceased to expand or progress, became mixed up with fanciful notions, and only recovered when a knowledge of ancient science and thought was restored in the fifteenth century.  But in geography we can more easily see than in other sciences the exact nature of the disturbing influence which prevented the acquisition of new knowledge.

[Footnote 1:  It is fair to add that Professor Miller’s researches have shown that some of the “unscientific” qualities of the mediaeval mappoe mundi were due to Roman models.]

Briefly put, that disturbing influence was religion, or rather theology; not, of course, religion in the proper sense of the word, or theology based on critical principles, but theological conceptions deduced from a slavish adherence to texts of Scripture, very often seriously misunderstood.  To quote a single example:  when it is said in Ezekiel v.  S, “This is Jerusalem:  I have set it in the midst of the nations... round about her,” this was not taken by the mediaeval monks, who were the chief geographers of the period, as a poetical statement, but as an exact mathematical law, which determined the form which all mediaeval maps took.  Roughly speaking, of course, there was a certain amount of truth in the statement, since Jerusalem would be about the centre of the world as known to the ancients—­at least, measured from east to west; but, at the same time, the mediaeval geographers adopted the old Homeric idea of the ocean surrounding the habitable world, though at times there was a tendency to keep more closely to the words of Scripture about the four corners