Annotating the Epilogue The traditional definition of an epilogue is that it is a concluding part of a literary work.
The closing section of Into the Wild ultimately makes clear that it is impossible to ever truly, fully understand another person. Krakauer spends three years researching McCandless’s life and journeys, and he has many parallels in his own life to help him understand, but he still cannot, in the end, say with any certainty what ultimately led McCandless into the wild, and why he didn’t survive the foray, but instead died, alone, at twenty-four. He cannot even say with absolutely certainty what killed McCandless. And although he attempts to find some answers by highlighting all the examples of times McCandless almost made a decision that could have saved him, in the end it is only conjecture, since this book is not fiction but fact, and can only have the ending which actually happened.
http://www.gradesaver.com/into-the-wild/study-guide/summary-chapters-17-18-and-epilogue
