One shared theme between both works is how people have to discover the truth apart from conventional society. Huck and Jim have to leave society in order to find their own sense of identity and their own sense of hope. They cannot remain in their own social setting and expect to find what it is they seek. The Joads might want to stay, but they are forced to move and with moving to California, they also realize that truth and identity exist outside of society. A shared theme exists in how the protagonists of both works have to leave society in order to find truth and meaning. This represents another shared theme in both works. The journey is of significant importance to both novels. Twain depicts the journey theme as what binds Huck and Jim together. Their journey down the Mississippi is where meaning exists and the journey, itself, represents a form of understanding about the world and their place in it. Huck and Jim as well as the Joads do not have a fixed destination in mind. They are not moving to a specific and firmly defined point. They move in the need to find hope, their own sense of freedom, or both. In this, the journey is just as important as the destination.
The theme of individuals having to listen to their conscience is of vital importance in both works. Huck cannot stand by and see Jim suffer. Even though he has been taught that to do so is wrong, Huck recognizes Jim's pain and his predicament compels Huck to act. Huck takes action because "got to troubling me so I couldn't rest." This is the same element seen in the Joads, where Ma recognizes that there is an obligation to help others, even if they are so very poor. The extra food she makes for other children, or the need to tell her family to share what they have, and the look she gives to Rose of Sharon at the end of the novel when both know what must be done for those who are dying of hunger are examples of how Steinbeck shows the need for individuals to take action in the name of conscience. Both works display the need for individuals to adhere to conscience when deciding what to do and how to act in the world.