In the present as in the foregoing parts of this book the attempt is made to distinguish between these two distinct types of geographical lore. For many regions the geographical ideas are indicated that were derived from Pliny, Solinus, Isidore, Bede, and other encyclopedists and that found expression in treatises like the _De imagine mundi_, the _Otia imperialia_, and the _Image du monde_. In contrast to these there is set forth the kind of information that was being gathered by contemporary eyewitnesses. GRADATIONS OF ACCURACY OF KNOWLEDGE Maps are sometimes drawn at the present day to show the state of progress of geographical knowledge. Upon these by various tints or shadings are indicated tracts that are accurately surveyed, partially surveyed, known only through route traverses, known only through reports from natives, or totally unknown. No such map could be constructed to show the character of regional knowledge in the Middle Ages, because our sources of information are not sufficiently complete and because the knowledge both actually and potentially available varied from country to country, from community to community, even from individual to individual. The printing press and facility of communication between the peoples of the world has rendered scientific knowledge or, at any rate, the possibility of obtaining scientific knowledge the common property of all modern civilizations. An Australian student, for instance, if he is willing to take the time and trouble, can learn through research virtually all that is known to Danish or Icelandic scholars about the geography of Greenland. In the Middle Ages, on the contrary, we may feel certain that the Danes and Norwegians had at hand much detailed information on Greenland and the Arctic shores of Europe that the Italian had no means whatever of obtaining. Correspondingly, the Italian trader of Genoa or Venice unquestionably knew a great deal about remote parts of Asia and North Africa that could never reach the ears of an author of a _De imagine mundi_ or of a Lambert of St. Omer, writing in quiet cloisters of France or Belgium.