Writers of the Middle Ages did not specialize as we do at the present day. They treated subjects of the most diverse nature within the pages of the same book. We shall group their productions into a few broad categories: philosophical and theological writings that were read for the most part by the scholar and churchman; translations from Arabic scientific treatises and other works written under Arabic influence; encyclopedic compilations or attempts to encompass the whole range of human learning, also for the scholar, and popularizations of these in prose and verse for the intelligent layman; histories and chronicles; pilgrim narratives and other records of travel; topographical works; and, finally, maps. Other more instructive classifications might well be made. One in which the works were grouped according to the type of thought of which each is the expression might bring out the conflicting intellectual crosscurrents of the age. In such a classification the great differentiation could be emphasized between writers bound by respect for authority and writers of originality and independence; between those who interpreted the words of Scripture literally, those who interpreted them allegorically, and those who went so far as to neglect or to doubt them. The classification which follows, based upon the purposes which the various groups of writings were intended to serve, is merely one of convenience. _THEOLOGICAL AND PHILOSOPHICAL WORKS_ The distinction between theology, philosophy, and the physical and natural sciences was not sharply drawn during the earlier Middle Ages. Only after the ninth century did the tendency to mark off theology and philosophy as separate spheres of thought become gradually evident,[368] and it remained for a much later age to set off the physical and natural sciences from philosophy. THEOLOGICAL WORKS Though not much geography is found in the strictly theological writings of our period, those portions of them which deal with the Creation embody cosmogonic and cosmographic speculations which have a geographic character for reasons that have already been explained.[369] Many of the philosophical writings, on the other hand, are rich in passages of geographical interest; for the physical geography, like the natural history, of the Middle Ages was the province of the philosopher. _Peter Abelard_