Like beautifully layered rock formations lining the walls of a desert canyon, so is the Biblical text. Story is piled upon story until the foundations are invisible. Those foundations tell a different story-one that only a trained geologist can tease from the rock, one that only a Biblical philologist, trained in the dissection of literature, can find in the text. Only by patiently chipping away at the later narrative layers of the book of Genesis do we discover that Abraham may actually have sacrificed Isaac, or that Jacob may have had only seven sons instead of twelve. Without these tools, there would be no way for us to know that the Israelites' sojourn in Egypt lasted only a few generations, not 430 years, and that when they escaped from Egypt, they numbered just 3,000, not 3,000,000. We would not know that according to the original story, the ancient Israelites escaped from Egypt immediately after the plague of darkness, or that only seven commandments were given at Mount Sinai, not ten.