One distinctly new idea, however, was introduced by the Bible into the circle of what we may, with a slight stretch of the imagination, consider the medieval physical geography of the water element. This new conception tended to revolutionize theories based on classical physics and to cause much confusion and doubt in the minds of the Fathers of the Church. The orthodox classical physicists had held that the elements normally form four concentric spheres surrounding the center of the universe, in order, from the heaviest to the lightest, earth, water, air, fire. Genesis (i, 6–7) states that “God said: Let there be a firmament made amidst the waters; and let it divide the waters from the waters. And God made a firmament, and divided the waters that were under the firmament from those that were above the firmament.” Though belief in waters above the firmament is found in the cosmologies of the ancient Egyptians and Persians and is there closely associated with belief in a disk-shaped earth covered by a dome-shaped heaven, water in such a position was very far removed from its proper place in the scheme of nature of Aristotle and his followers. The Church Fathers, nevertheless, were unwilling to doubt the actual existence of these waters, and in general they accepted the text literally.[251] Gregory of Nyssa even went to the extent of imagining mountains on the back side of the firmament and that the waters were contained in the hollows and valleys between them.[252] Others thought the waters were in the form of clouds or fine drops. Jerome, Josephus, Ambrose, and Bede all held that the waters were crystal.[253] Augustine was non-committal, though he gathered together the statements of many who had expressed concrete views on the subject.[254] Ambrose argued from analogy that if the earth can hang in the center of the universe without support so also can the waters hang unsupported above the firmament.[255] The purpose which the waters were to serve was also a thorny problem. Ambrose said they were intended to cool the axis of the universe, overheated by its perpetual rotation;[256] others thought that they were meant to screen the earth from the fiery heat generated by stars and sun;[257] others that they were stored up as a reservoir to supply hydraulic resources at the time of the Great Flood.[258] THE CONGREGATION OF THE WATERS