The Oppression of Women
The primary female characters -- Maria and Jemima -- are both representatives of the oppressed class. Because they are women, they are denied many inherent rights. As an unmarried woman, Maria is not allowed to own her own property or finances, or to remain the primary caregiver for her daughter. Neither of the women is given autonomy over her own body, often becoming the complete and totally dependent subject of a master/husband.
Insanity As a Last Resort
The insane asylum where Maria finds herself locked away is a sort of catch-all for other systems in society. People are not necessarily placed here because they are insane. More often than not they are merely people who have become a burden to their society. For instance, Darnford is placed there because of his constant intoxication, having become too much of a regular in the local jail. They decide his problem is too complex to be handled by the criminal system. Similarly, Maria has no place else to go because of her husband's rejection of her and his clever scheme to discredit her as an heir to his estate.
Escape
Another prominent theme throughout this book is escape. For the most part, Maria's life is defined by her need to escape her circumstances. She is abused in every household in which she lives. People take advantage of the weakness of her physical body as well as her lack of legal protections in order to rape, extort, and abuse her. Her entire life is one long effort to find safety and freedom. By the time she is locked away, she has adopted an identity of displacement. Her true escape occurs in the form of her message to her child, as a sort of vicarious delivery device for her values.
