Describe symbolism in Who Wrote the Bible? by Richard E. Friedman

Friedman puts the dates of writing Genesis as J being from 848 and 722 B.C., and E from 922 to 722 B.C. Friedman argues that the two were combined because of the respect for ancient texts and the social need for familiar stories to be retained. Had either J or E been cut out, either former Judeans or former Israelites would have complained. The combination of the two texts symbolizes the reuniting of the Jewish people 200 years after the north and south kingdoms had existed.