One of the primary themes in Mark Twain's The Adventures of Huckleberry Finn is freedom--and the lack of it.
Jim is a slave who literally does not have his freedom. He escapes in order to avoid being sold down the river, and he is desperate for his freedom. It is a complicated and confusing journey in which Jim is freed then enslaved several times before he learns that his owner dies and freed him in her will. For much of the story, then, Jim was a free man (though he did not know it) who was still living as if he were a slave.
Huck is also in a kind of bondage and wants his freedom. His father is a drunkard who lives in the woods (where Huck is most comfortable physically) and his aunt lives in town among acceptable society but tries to "civilize" Huck (which he hates). The result is that he is not comfortable in either world and feels trapped. He travels with Jim in order to escape something more than to find something.
The other major theme in this novel is, of course, race. It is a complicated issue in this novel, just as it often is in real life. While Huck wants to respect Jim as an equal--and often does--there are times when Jim is still very much the inferior slave to Huck's white mastership. Despite his father's stereotypical, racist view of the relationship between blacks and whites, Huck is able to see beyond color much of the time. This sliver of hopefulness is probably not enough to explain Huck's desire to free Jim; however, race is often a complicated issue, as we all unfortunately know. Huck does admit:
“Just because you’re taught that something’s right and everyone believes it’s right, it don’t make it right.”
Themes are the ideas, often universal concepts, that are explored in a piece of literature. In Mark Twain's book "Huckleberry Finn," one theme that is explored is "Racism and Slavery." Even though Mark Twain wrote his book after slavery had been abolished, the South was still struggling with reconstruction and prejudice, and Twain set the book decades earlier during a time when slavery still existed in order to comment on the evils of racism that still marked the culture around him. Mark Twain wrote to expose the hypocrisy behind racism, how seemingly "good" white people are apathetic to the evils of slavery and racism. He also wrote to show how racism destroys the people who are racist just as much as it hurts the victims of racism, and how it creates a twisted society.
Another theme is that of the "Hypocrisy of Civilized Society," and what it means to be truly civilized morally and intellectually. Twain exposes the corruption and selfishness, the lack of logic and the cowardice that marks more "civilized" people. The society that surrounds Huck is little more than a collection of rules and precepts that defy logic. And who are the real heroes that we are to admire and emulate in the book? How are they treated, and by whom? Civilized people are most often the culprit in this book.