What are the themes of The Kitchen House?

One of the book's most notable themes is the lack of freedom that so often ruins poor people's lives. After being orphaned, Lavinia is forced to work as an indentured servant on a large Southern plantation called Tall Oaks. Indentured servitude essentially involved working for your keep and was a common practice at the time. It was a very hard life, as Lavinia discovers for herself growing up during her time at Tall Oaks.
Initially, she doesn't understand the difference between indentured servitude and slavery; both servants and slaves alike are treated abominably. But as she gets older, the differences between the respective states become all too apparent. Life may be hard for a (white) indentured servant, but it's a walk in the park by comparison with what slaves such as Belle must go through.
Nevertheless, Lavinia experiences her own form of domestic slavery when she winds up getting hitched to the violent, overbearing Marshall. As a member of the privileged white race, Lavinia cannot, of course, be a slave. But as a woman, and a poor woman at that, she can still be deprived of freedom by a society that regards her as a second-class citizen and by a brute of a husband who thinks he's entitled to control every aspect of his wife's existence.