The real tragedy of Don Quixote wasn't the knight's madness, his rusty armor, his sickly horse, nor even his miserable failure at feats of arms-the tragedy was that at the end of the book, he "recovered." A perfectly nice, if anachronistic, Medieval put aside his chivalry and became a disillusioned Modern. And that's what has become of Thomas Cahill, author of the delightful How the Irish Saved Civilization. His latest book, The Gifts of the Jews, is a disappointment. How the Irish Saved Civilization was filled with happy medieval concepts. In telling the story of the Irish monks who preserved the classics then revived learning in the universities, Mr. Cahill made real, live judgments. The classics were good; the barbarians were bad. Learning and literature are good; raping and pillaging are bad. The Gifts of the Jews is a much more modern book. Mr. Cahill adopts all the correct attitudes and throws in all the necessary equivocations. "What a bizarre phenomenon the first human mutants must have appeared on the earth," he speculates. And he assumes he's writing to an equally modern audience. "But even without resorting to modern scientific methodology or noticing what an inconsistent palimpsest the Hebrew Bible can be," he writes, "we must reject certain parts of the Bible as unworthy of a God we would be willing to believe in." Still, the book is not without merit. Mr. Cahill does a good job of explaining the ancient mindset, much the same way C.S. Lewis explained the medieval mindset in The Discarded Image. Ancients in Ur and Canaan saw life as circular. "In the revolving drama of the heavens, primitive peoples saw an immortal, wheel-like pattern that was predictive of mortal life. At the center of this Wheel of Life they found the Hub of Death." Avram (Mr. Cahill uses this form of Abram) was unique in that he broke out of the circle. He did something new. At God's instructions, he left Ur and went to a new land; "this particular migration would change the face of the earth by permanently changing the minds and hearts of human beings." Ultimately, though, Mr. Cahill's modernism cripples the book. "It is no longer possible to believe that every word of the Bible was inspired by God," he writes. "Fundamentalists still do, but they can keep up such self-delusion only by scrupulously avoiding all forms of scientific inquiry." What about the self-delusions of those who know what is needed to save other civilizations, but not their own?