By doing so, she is willing to provide an answer to a question that some historians would say is unanswerable, namely -- how could Bertrande be so deceived, and what would be her motivations in keeping up such a ruse? Davis suggests that her motivations were economic, personal, and social, and were the production of various historical forces, like the rise of Protestantism and the new value accorded to individual choice in society. Of course a dissenter might respond that the reason Davis' psychological reading is so persuasive to a modern reader is because it comes from the mind of a modern woman, and the tale is told to appeal to modern-day readers, just like a film. We value individual choice, and the right of a woman not to suffer in misery, in the thrall of an unfair law that makes her a nonperson because her husband leaves her yet refuses to end the marriage by annulment or divorce. If you want fiction, a historian might...

She also is able to show that Bertrande's motivations were not just romantic or sexual, but were also rooted in her desire to survive. Davis can also add a great deal of back history, so the reader understand that Bertrande was a woman of her time, as well as an extraordinarily strong and resourceful woman, and that there were many intelligent and capable women living in the Middle Ages. Davis also brings to life with clarity and comprehension the system of justice at the time, which was far more draconian than our own (identity theft was a capital crime) but also far more reasonable than media stereotypes of Medieval justice might suggest.
Works Cited

Davis, Natalie Zemon. The Return of Martin Guerre. Cambridge: Harvard University Press, 1984.