Class Conflict
The theme of class conflict does not just lie at the center of this novel, it the engine powering the narrative. The title character is the primary representative of the upper middle class. The De Courcy family are the villainous representatives of inherited aristocratic power. Criticism has been leveled at the author for making his sympathies too clear through creating a caricature of the aristocracy while Thorne is more fully humanized. This critique is only fair if it were not clear that the book is unambiguously supporting the democratic message of the story.
The Necessity of Money
The broader theme encompassing all the characters is the necessity of money to survive in society and what people are willing to do to get it. Lady Arabella De Courcy Gresham's constant refrain is that her son "Frank must marry for money. This goal is actually painted by his mother as her son's one "duty." Despite the Gresham being aristocrats and wealthy through inheritance, they are also deeply indebted to the mortgage on their ancestral home. The thematic exploration here is that even the upper classes are at the mercy of money in modern society. While this theme is presented through events, it is also the central theme which is presented through the idiosyncratic voice of the narrator. His asides and digressions provide running commentary illuminating this subject.
Illegitimacy
Another way of describing this theme is the story is about "good blood" versus "bad blood." In the aristocratic system, lineage outweighs everything else. Mary Thorne is the representative of illegitimacy in this story. The status available to one in her position is limited simply as a result of not having good enough blood. This conflict contributes to the novel's larger concerns with democratic equality versus aristocratic inequality. The illegitimacy of Mary is a metaphor for the illegitimacy of aristocratic ideals.
