The conventional orthodox position, however, did not remain unchallenged. The influx of Moslem Aristotelian lore at the end of the twelfth century was held to be as menacing to the integrity of the ecclesiastical tradition as any of the Platonic doctrines. But, though stern prohibitions were leveled against the study of Aristotle and his Arabic interpreters, the seductions of Aristotelianism could not be resisted, and those elements of Peripatetic science which did not seem utterly outrageous to Christian theology became the accepted and authoritative science of the West in the mid-thirteenth century. William of Auvergne, bishop of Paris, stood out valiantly against what he regarded as teachings subversive of Christianity and of morals and in his vigorous opposition to Aristotelianism even went so far as to adopt many of the Platonic doctrines that had been popular among the scholars of Chartres during the preceding century.[587] But translators like Gerard of Cremona had done their work too well, and the enormous tomes of Albertus Magnus were based to a large extent on the learning of the Stagirite. _THE CREATION_ The usual medieval treatise on the Works of the Six Days as described in the Book of Genesis deals with many problems. Some of these are abstruse and metaphysical: questions of the nature of God and the nature of time and space. With these we are not concerned. Others are more concrete: questions of the materials out of which God made the universe and of the actual manner in which he worked. PROBLEMS For the sake of clearness let us state some of these questions as follows, (1) The question of whether matter existed prior to God’s creation of the world. That is to say, Did God fashion the universe out of a pre-existing substance or did he make it out of nothing? (2) The question of the manner in which the universe was fashioned after it was once “created.” (3) The question of what furnished the light during the first three days before the creation of the sun. (4) The problem of whether the Six Days were actual divisions of time or merely hypothetical divisions of the process of creation. (5) The question of the nature of the waters above the firmament. (6) Various problems arising in regard to the nature and location of Paradise and of the four rivers flowing from Paradise. The first four problems are discussed briefly in the present chapter. That of the waters above the firmament is left for Chapter VIII (on waters), and that of Paradise for Chapter XII (on regional geography). THE PREËXISTENCE OF MATTER (1) Did matter exist prior to God’s creation of the universe as we now know it? Consistently with his Platonism, Bernard Sylvester thought that God formed the universe out of what he termed _materia primordialis_—a chaotic mingling of the elements that had coexisted with God before he converted the universe into its present shape.[588]