Though it is not now regarded as lying strictly within the field of geography, the history of the evolution of theories about the origin of the earth is so closely allied to the history of geography that the two cannot well be dissociated. A marked antagonism inevitably arose between the usual Greek view, which regarded matter as eternal, and the Christian view, which was based on the first chapter of Genesis and conceived of the universe as created at a definite point in time or concurrently with time. The men of the Middle Ages tended to adhere strictly to the Christian opinion, for to have done otherwise would have been heretical. Nevertheless, the ancient theory was well known to Christians and exerted in its various forms no small influence on the development of certain phases of Christian thought. CELESTIAL INFLUENCES It was a deeply rooted belief of many classical thinkers that the events and conditions on this world and on all the regions below the sphere of the moon’s orbit are regulated by the heavenly bodies. Aristotle and his followers taught that the heavenly bodies themselves are made of an imperishable and incorruptible, almost divine, fifth element, ether, which distinguishes them from the four corruptible elements (fire, air, water, and earth) that constitute the immediate world of our senses.[12] By virtue of this semi-divine quality, it was argued, the sun, planets, and stars exert an all-powerful control over the earth around which they revolve—an absolutely determining control over all events both great and small.[13] From this fatalistic belief sprang the science of astrology, a science which throughout antiquity was held in equal esteem with astronomy. The study of the movements of the celestial bodies revealed the fact that at some time in the distant future, sun, planets, and stars will bear exactly the same relative position one to another that they do at the present moment. Consequently, it was inferred that the influence exerted by them on the sublunar regions will at that time be exactly the same as it now is, and all the phenomena now apparent on the earth’s surface will be exactly repeated. They will be repeated not only once but an infinite number of times at periodic intervals in the future; similarly they have been repeated throughout infinite cycles in the past.[14] COSMIC CYCLES: THE GREAT YEARS