Conflict between civilization and "natural life"
The primary theme of the novel is the conflict between civilization and "natural life." Huck represents natural life through his freedom of spirit, uncivilized ways, and desire to escape from civilization. He was raised without any rules or discipline and has a strong resistance to anything that might "sivilize" him. This conflict is introduced in the first chapter through the efforts of the Widow Douglas: she tries to force Huck to wear new clothes, give up smoking, and learn the Bible. Throughout the novel, Twain seems to suggest that the uncivilized way of life is more desirable and morally superior. Drawing on the ideas of Jean-Jacques Rousseau, Twain suggests that civilization corrupts, rather than improves, human beings.
Honor
The theme of honor permeates the novel after first being introduced in the second chapter, where Tom Sawyer expresses his belief that there is a great deal of honor associated with thieving. Robbery appears throughout the novel, specifically when Huck and Jim encounter robbers on the shipwrecked boat and are forced to put up with the King and Dauphin, both of whom "rob" everyone they meet. Tom's original robber band is paralleled later in the novel when Tom and Huck become true thieves, but honorable ones, at the end of the novel. They resolve to steal Jim, freeing him from the bonds of slavery, which is an honorable act. Thus, the concept of honor and acting to earn it becomes a central theme in Huck's adventures.
Food
Food plays a prominent role in the novel. In Huck's childhood, he often fights pigs for food, and eats out of "a barrel of odds and ends." Thus, providing Huck with food becomes a symbol of people caring for and protecting him. For example, in the first chapter, the Widow Douglas feeds Huck, and later on Jim becomes his symbolic caretaker, feeding and watching over him on Jackson's Island. Food is again discussed fairly prominently when Huck lives with the Grangerfords and the Wilks.
Mockery of Religion
A theme Twain focuses on quite heavily on in this novel is the mockery of religion. Throughout his life, Twain was known for his attacks on organized religion. Huck Finn's sarcastic character perfectly situates him to deride religion, representing Twain's personal views. In the first chapter, Huck indicates that hell sounds far more fun than heaven. Later on, in a very prominent scene, the "King", a liar and cheat, convinces a religious community to give him money so he can "convert" his pirate friends. The religious people are easily led astray, which mocks their beliefs and devotion to God.
Superstition
Superstition appears throughout the novel. Generally, both Huck and Jim are very rational characters, yet when they encounter anything slightly superstitious, irrationality takes over. The power superstition holds over the two demonstrates that Huck and Jim are child-like despite their apparent maturity. In addition, superstition foreshadows the plot at several key junctions. For instance, when Huck spills salt, Pap returns, and when Huck touches a snakeskin with his bare hands, a rattlesnake bites Jim.
Slavery
The theme of slavery is perhaps the most well known aspect of this novel. Since it's first publication, Twain's perspective on slavery and ideas surrounding racism have been hotly debated. In his personal and public life, Twain was vehemently anti-slavery. Considering this information, it is easy to see that The Adventures of Huckleberry Finn provides an allegory to explain how and why slavery is wrong. Twain uses Jim, a main character and a slave, to demonstrate the humanity of slaves. Jim expresses the complicated human emotions and struggles with the path of his life. To prevent being sold and forced to separate from his family, Jim runs away from his owner, Miss Watson, and works towards obtaining freedom so he can buy his family's freedom. All along their journey downriver, Jim cares for and protects of Huck, not as a servant, but as a friend. Thus, Twain's encourages the reader to feel sympathy and empathy for Jim and outrage at the society that has enslaved him and threatened his life. However, although Twain attacks slavery through is portrayal of Jim, he never directly addresses the issue. Huck and Jim never debate slavery, and all the other slaves in the novel are very minor characters. Only in the final section of the novel does Twain develop the central conflict concerning slavery: should Huck free Jim and then be condemned to hell? This decision is life-altering for Huck, as it forces him to reject everything "civilization" has taught him. Huck chooses to free Jim, based on his personal experiences rather than social norms, thus choosing the morality of the "natural life" over that of civilization.
Money
The concept of wealth or lack thereof is threaded throughout the novel, and highlights the disparity between the rich and poor. Twain purposely begins the novel by pointing out that Huck has over six thousand dollars to his name; a sum of money that dwarfs all the other sums mentioned, making them seem inconsequential in contrast. Huck demonstrates a relaxed attitude towards wealth, and because he has so much of it, does not view money as a necessity, but rather as a luxury. Huck's views regarding wealth clearly contrast with Jim's. For Jim, who is on a quest to buy his family out of slavery, money is equivalent to freedom. In addition, wealth would allow him to raise his status in society. Thus, Jim is on a constant quest for wealth, whereas Huck remains apathetic.
Mississippi River
The majority of the plot takes place on the river or its banks. For Huck and Jim, the river represents freedom. On the raft, they are completely independent and determine their own courses of action. Jim looks forward to reaching the free states, and Huck is eager to escape his abusive, drunkard of a father and the "civilization" of Miss Watson. However, the towns along the river bank begin to exert influence upon them, and eventually Huck and Jim meet criminals, shipwrecks, dishonesty, and great danger. Finally, a fog forces them to miss the town of Cairo, at which point there were planning to head up the Ohio River, towards the free states, in a steamboat.
Originally, the river is a safe place for the two travelers, but it becomes increasingly dangerous as the realities of their runaway lives set in on Huck and Jim. Once reflective of absolute freedom, the river soon becomes only a short-term escape, and the novel concludes on the safety of dry land, where, ironically, Huck and Jim find their true freedom.
