Dr. Field, an anthropologist and psychiatrist, spent 35 years in West Africa, and this book combines his professional training and experiences in the evolution of a hypothesis concerning certain hitherto unexplained phenomena of the Bible -- angels, particularly, and prophets. His clinical and empirical approach leads to interesting conclusions. The ""cloud,"" for instance, by which Moses communicated with his deity, may have been the drug -- nitrous oxide, obtained by sprinkling ammonium nitrate on a hot metal dish. (The author has seen this same drug used, with comparable results, by African shamans.) Even more interesting is Dr. Field's explanation of the angel Gabriel, who, he says, simultaneously announced to Mary that she would bear a child and impregnated her -- ""there is no need to suppose that Mary was consciously unfaithful to her husband."" A great deal of what the author has to say makes good sense, but some of it is nothing more than pure conjecture. All of it, however, is well said and designed to delight the reader who takes his de-mythologizing straight.