Another Biblical phrase that provoked discussion of the problems of hydrography was in the one hundred and thirty-fifth Psalm (Vulgate): “Praise ye the Lord of lords, ... Who established the earth above the waters” (_qui firmavit terram super aquas_). Many writers took this literally and thought of the earth as actually floating upon water, held up by the arbitrary force of God’s will. A few, despite the explicit words of Scripture, were inclined to doubt; they either explained the phrase by urging that the word “above” (_super_) should be taken to mean “beside” or argued that all that was meant here was that the land rises to a higher level than the sea.[266] The difficulty was also avoided, as was frequently the case with puzzling Scriptural passages, by saying that the passage was allegorical and should not be taken literally. THE SEA There is not much to record about the development of knowledge or theory concerning the physical geography of the sea. The ancients themselves had known little enough about the sea to pass on to an age when maritime ventures were almost unknown—to learned men at least—and certainly we cannot find a great deal of marine lore in the Bible. Occasional glimmerings of intelligence, however, break the darkness of the times in this respect. Dicuil, for instance, in his _De mensura orbis terrae_, questions Fabianus’ statement that the sea is at most fifteen stades deep. “Has Fabianus measured its depth?” he asks; “if not, how can we believe what he says?”[267] Bede understood the difference in density between fresh and salt water; and in accord with Isidore and others he explained why the seas do not overflow their banks by pointing out that water is constantly being removed into the air and into the land.[268] Though the Church Fathers stood out valiantly against those teachings of astrology which tended to exaggerate the powers of the heavenly bodies, they were none the less ready to admit that the moon may exert a physical attraction on the ocean and in that way may produce the tides. Basil even explained that there is a corresponding lunar control over the atmosphere.[269] Augustine and Ambrose believed that the moon causes tides;[270] and a certain Augustine, writing in the seventh century, described the spring and neap tides and tried to show how they follow not only the moon’s phases but also the equinoxes and solstices. He made a serious mistake by placing spring tides at the time of the solstices.[271] Bede corrected this in his _De natura rerum_, apparently from personal observation—a rare thing at this time—and noted a number of tidal peculiarities which had not been commented on before.[272]