The movie is based in an homonymous novel written by Jon Krakauer, in 1996. And that novel was based on historical facts, relating the history of a young man, an universitary named Christopher McCandless, that because of his family life, the relationship with his family, and because of the usual behavior and way of life of his family, decides to leaving home, and go for adventures, to contact with himself, to know how's the real life, how's the life in extreme conditions. Plus leaving his family, home, city, he leaves too all the "city things", like money, car, and those kind of things that are not necessary in an natural enviroment. After leaving his home, he go across the fields, canyons, mountains, until he arrived to his objetive... Alaska.
This is a similitude with the book "The Call of the Wild", written by Jack London at 1903, that relates the history of a dog, a southern dog, that lives in a ranch ubicated in California, who is stealed and translated to the north of the country, to Canada, to Alaska, to work like sled dogs, in extreme conditions.
That similitude, shows us a diferent view of the life, of the way of life, of the freedom and the work.
On the movie, the protagonist dies at the end, like a redemption of the life... And in the end of the book, the dog becomes a wolf, like the return to the origin, the return to the natural enviroment, without city's comfort and restrictions of freedom.
This Image shows a phrase of the movie. This phrase means the discovering of leaving in the nature alone, like the key message of the film.
And that's the cover of the book, with an ilustration tha represents the dog pulling the sledge.
This is part of the original soundtrack of the movie, a song written by Eddie Vedder, the vocalist of Pearl Jam.