Though it cannot be proved that Otto of Freising made use of these works, nevertheless his philosophy of history is to a large extent based on the theory of the westward flow of civilization.[1071] In the prologue to his _Chronicon_ he queries, “Who can wonder that human power is changeable, when mortal wisdom also is unstable (_labilis_)? What great learning there was in Egypt and among the Chaldeans, from whom Abraham derived his knowledge! But what now is Babylon, once famous for its science and its power? A shrine of sirens, a home of lizards and ostriches, a den of serpents! And Egypt is now in large part a trackless and uninhabitable waste, whence science was transferred to the Greeks, then to the Romans, and finally to the Gauls and Spaniards. And,” he concludes, “let it be observed that because all human power or wisdom began in the Orient and will end in the Occident, the mutability and disappearance of all things is demonstrated. This I propose, with God’s aid, to make clear in the work which follows.” Otto again hammers on this theme in the prologue of his fifth book[1072] and finally, near the close of the same book,[1073] remarks, “For behold, as I have explained above, just as the heavens turn from east to west, so we behold worldly affairs and powers revolving.” If human power is so changeable, he asks, who can expect that the Kingdom of the Franks will last very long? The idea that “westward the course of empire takes its way” was thus raised in the Middle Ages to a position of theological doctrine and philosophical principle. _FEELING FOR LANDSCAPE AND SCENERY_ The pagan, or classical, attitude toward nature was characterized by a subjective and esthetic enjoyment of beautiful scenery; the Christian saw in nature the symbol and manifestation of the divinity.[1074] Both points of view were represented in the literature of our age. SPIRITUAL FEELING FOR NATURE