This was derived for the most part from two fountainheads of original observation and thought: (1) the writings of Greek historians and philosophers and (2) the Bible. Greek geography was the main source whence Latin writers of the Roman Empire and Moslems of the eighth, ninth, and tenth centuries of our era found their inspiration and facts. The Bible, as interpreted in the exegetical works of the Church Fathers, stimulated thought on geographical problems. The scholar of our period had at his disposal many Latin writings, both classical and patristic, and a somewhat more limited number of Arabic books and translations from the Arabic. ORGANIZATION OF THE PRESENT WORK The aim of the first three chapters of our study is to give an estimate in broad outline of the contributions of classical, patristic, and Oriental geography to the medieval West. The purpose is to show the kind of geographical ideas which a reader of the twelfth or thirteenth century might have gathered from older works in the libraries and to reveal something of the evolution of these ideas. No attempt is made to discuss works not well known in the Occident. The writings of famous Greek geographers like Herodotus, Pausanias, Strabo, Eratosthenes, Hipparchus, and Ptolemy receive only scant attention, and their contents are noted only in so far as they became familiar to Western Christendom through Latin media. Similarly the Greek Fathers of the Church and most of the more important Moslem geographers are overlooked because they exerted almost no influence on Western thought. Nor within the period itself that forms the subject of our investigation is much space given to writers like the Moslem Edrisi or the Greek Michael Psellos, whose researches did not contribute materially to the formation of Western science. After a fourth chapter, on the literary and cartographic sources which date from the time of the Crusades and upon which our estimate of the geographical lore of this age is based, and a fifth, on the place of geography in the medieval scheme of learning, there follows the main part of this book. The attempt is here made to illustrate from representative sources geographical lore of all kinds, whether original or borrowed, to emphasize evidences of originality where they are apparent, and to trace a few significant borrowed theories to their origins. Though the period under consideration lasted a century and a half, there was not much change during this time in the quantity of geographical information available or in the quality of geographical thinking. Hence it will be more convenient and enlightening to adopt a topical and regional arrangement for the main portion of our treatment than to try to arrange the material chronologically.