The medieval mind tended to seek for a logical and symmetrical subdivision of the sum of all knowledge. The desire for systematization found its supreme expression in the great philosophic structures of the thirteenth century, the systems founded on Aristotle and devised by such men as Albertus Magnus. Prior to the thirteenth century confusion had reigned. According to the Platonists, who divided philosophy into logic, ethics, and physics, the study of the mathematical and natural sciences—and, therefore, of geography—fell under the heading of physics. Aristotle, more logically perhaps, had divided the subject matter of all human learning into two great categories, theoretical knowledge and practical knowledge. Theoretical knowledge included physics, mathematics, and metaphysics (or theology). The studies of the quadrivium were thrown by the Aristotelians under the heading of mathematics: geography, then, became to those who followed the Aristotelian classification—Gondisalvi, Hugh of St. Victor,[564] Roger Bacon—a sub-department of mathematics. But on the whole we need not linger over this topic, because the question of exactly where geography belonged in the artificial systems devised by the medieval mind was largely a matter of academic interest even in the Middle Ages and was without influence on the actual condition of the geographical lore of that time. PART II THE SUBSTANCE AND CHARACTER OF THE GEOGRAPHICAL LORE OF THE TIME OF THE CRUSADES CHAPTER VI COSMOGONY, COSMOLOGY, AND COSMOGRAPHY In the preceding chapters the attempt has been made to show the origins of a large part of the geographical lore of the Crusading epoch, the sources from which we may learn about it, and where it stood in the classification of learning. Now we may turn to our central theme: an estimate of its actual substance and character. This geographical lore was in no sense a unified body of knowledge and belief. It was no more a unit than the religious thought of the age, or the philosophy, astronomy, or morals. No one in the Middle Ages was acquainted with all the facts and theories with which we shall have to deal. Mental caliber, credulity, critical spirit, curiosity, opportunities for research and for travel—these all varied widely with the individual and determined his geographical concepts. Nevertheless, though there was no unity of knowledge or belief in regard to specific facts and no unity of point of view, the reader will not fail to perceive, in the multitude of illustrative details which are presented, that certain habits of thought and modes of expression were typical of the epoch as a whole.