In “Letters to a Stranger” (1956), Mauriac reflects on people’s behavior and morals, on the relationships between men and women, and on techniques of seduction—why some marriages turn out happy, why divorces happen, and why feelings fade. The author writes to a woman, but who she is remains a mystery to the reader. That’s how the Stranger appeared in Mauriac’s imagination: a female silhouette spotted by chance in the theater stalls, a lovely lady glimpsed somewhere amid the bustle of the day—someone the writer instructs, teaches life, and gently guides. These letters can teach us a great deal too—readers of the 21st century. They will be useful not only to women looking for support in this life, but also to men, who so often fail to understand the logic of behavior and the psychology of women.