The American frontier
In his book Love and Death in the American Novel, the literary critic Leslie Fiedler suggests that the central theme of all U.S. literature is the escape of American men and boys from civilization into the wild. Often a reaction to heartbreak, and sometimes in the company of other men and/or boys, this flight is the dynamic at the center of books and stories as diverse as Walden by Henry David Thoreau, Moby-Dick by Herman Melville,The Adventures of Huckleberry Finn by Mark Twain, "Big Two-Hearted River" by Ernest Hemingway, and many more. Jon Krakauer's Into the Wild shares the frontier theme with these great works of literature that preceded it, one of which (Walden) Christopher McCandless actually takes with him as he "lights out for the territories," in the words of Huck Finn.
Fathers and sons
The title of a book by the 19th-century Russian novelist Ivan Turgenev, Fathers and Sons, this is one of the main themes of Into the Wild. If there is a single turning point in the life of Christopher McCandless, it may be the discovery that his father had a second, secret family. This revelation seems to inspire him to reject his parents completely and commence an odyssey into wild America. Along the way, McCandless gravitates toward substitute fathers including Wayne Westerberg and Ronald Franz (and one substitute mother, Jan Burres).
Christopher McCandless denounces and rejects what he sees as American materialism, in general when he leaves his parents and the upper middle-class suburban setting in which they raised him, and very specifically and concretely when he donates all his savings to charity, abandons his car in the desert, and actually burns his paper money on the desert floor.
Survival in the wilderness
This is the central theme of the work of one of Christopher McCandless's favorite authors, Jack London. The most striking example of this is probably London's short story "To Build a Fire," about a man who freezes to death in the woods because of his inability to do precisely that. In a way, this story foreshadows McCandless's own fate.
Into the Wild is very much the story of a young man, of his energy, his idealism, and the arrogance that ultimately kills him. It is hard to imagine anyone besides a male in his late teens or 20s who would do and say the things that Christopher McCandless does and says in this book though, bizarrely, the octogenarian Ronald Franz tries to model aspects of his life after McCandless.