Well, at the surface, the point of this story is tell the history of Chris McCandless, a man who died at the age of 24 after taking off into the Alaskan wilderness. This man, who grew up in a fairly privileged lifestyle and who had much education, chose to set off into the woods of Alaska with little to no supplies, saying he was going to "live off the land." It was an odd thing to do, and the fact that McCandless died of uncertain causes while in the woods helped to make his story more fascinating. The author set out to discover what was driving McCandless and to tell his "true story".
What Krakeur does, however, is to use references to other famous wilderness experiences in order to make comparisons to Chris. The story becomes not just about Chris's journey, but about the alienation that humans often feel in their own lives and in society, and about the pull of nature to try to clarify meaning in life.
It is impossible to live off the land without discovering both a subtle understanding of, and a strong emotional bond with, that land and all it holds.
In this quote, Krakauer shows that being with the land can lead to an experience of enlightenment and can bring a sense of connection. Having seemed so lost in his own life, Karkauer suggests that Chris goes to the land to find his path, his place. The references to other writers and other wilderness travellers shows how common this ideas has been throughout history.