Krakauer begins each chapter with a quote from a reowned author. Why is his reasoning for doing this?

I think it's Henry David Thoreau. This guy had his own little hideaway in Walden. Here Henry David Thoreau espoused the magic of living away from society and not playing by the rules. It's that sort of independent "I don't need anybody because the squirrels are my friends" sort of thing. I think Waldo Emerson is quoted too. Anyhow, Chris idolized these guys.