In his consideration of the problem of the flood of the Nile, Abelard gives a curious example of the symbolic interpretation of scriptural and geographic matters which was also characteristic of the writings of Bernard of Clairvaux.[936] Isidore had followed earlier classical authorities in describing the flood as due to the building up, by the etesian winds, of sand bars at the mouth of the river during the winter.[937] Abelard, from Bede’s rendering of Isidore’s text,[938] adopted the same theory in his discussion of the Nile in the _Expositio in hexaemeron_.[939] He also discussed the Nile flood in a sermon on the text, “And the Lord, the God of hosts, is He who toucheth the earth, and it shall melt: and all that dwell therein shall mourn: and it shall rise up as a river and shall run down as the river of Egypt” (Amos ix, 5). In the sermon[940] he compared the rising of the Lord at the resurrection to the Nile: as the river fructifies the land, so the Lord strengthened the despairing hearts of his disciples. Abelard then quoted the passage from Bede just mentioned, and proceeded to interpret it as follows: The Nile coming down from Paradise is like unto the wisdom of God descending from above to give us to drink as from a fountain. Egypt is like unto the carnal darkness of this world. Its river enters the sea through seven mouths, which are obstructed when the wind blows and causes the backing up of the waters that can find no outlet. Thus, after the resurrection of the Lord but before the sevenfold grace of his spirit could find its way out into the broad sea of the nations, it was impeded as were the waters of the Nile. In other words, the apostles, through fear of the Jews, were held in Judea blinded, as it were, and for some time were not permitted to go forth as if from Egypt and through their preaching to bring about a rebirth of mankind. What does the wind represent, Abelard asks, if not the temptation of the devil? And what the sand, if not those men who at the turning of the ages wavered this way and that, held fast by earthly desires and temptations? [941] It is hardly necessary to point out the contrast between this sort of geographical speculation and that of William of Conches. Better perhaps than any other text with which the writer is familiar, these ideas of Abelard illustrate that absorption, so often characteristic of medieval thought, of scientific and geographical interests into those of theology. LAKES Abundance of lakes is characteristic of glaciated countries like New England, Switzerland, Scotland, Sweden, Wales, and Ireland. Giraldus Cambrensis was impressed by the number of lakes in Ireland, where, he says,[942] they are more numerous than in any other part of the world. Giraldus and Gervase of Tilbury describe many lacustrine marvels.