Author John Knowles weaves a very complicated theme of friendship throughout his novel A Separate Peace. It's not a standard friendship that the two main characters Gene Forrester and Phineas, called Finny for short, share with each other although Finny feels it is. Instead, though Finny places all of his trust in Gene, calling him his "best pal," Gene hesitates to reciprocate because he sees themselves as rivals. On the one hand, Gene feels drawn towards Finny's carefree spirit and wishes he could emulate that spirit, but on the other hand, he feels antagonized by Finny and envies his athletic abilities. The antagonization and eventual guilt he feels over causing Finny's injuries and later death are certainly developed in many uses of symbolism and metaphor, seen even in the very first chapter.
One example of symbolism can be seen in the first chapter when Gene returns to the school to again see the tree, 15 years after the events narrated in the story. Here, it becomes evident that the tree, which is normally symbolic of life, is symbolic of a war Gene has waged against himself in his own life. We see the tree symbolizing war in Gene's description:
[The tree] had loomed in my memory as a huge lone spike dominating the riverbank, forbidding as an artillery piece, high as the beanstalk. (p. 3)
Here, the images of spikes and artillery represent violence, destruction, warfare, and even death. Later, we come to understand that Gene's friendship with Finny represented a battle within Gene's own self. Finny was everything Gene wished he could be yet struggled to become. Due to his struggle to become what he was not, he felt antagonized by Gene and only felt at peace once he had ruined Finny's athletic abilities.
A metaphor that captures Knowles's theme of complicated friendship is found in this first chapter. Gene had come to see if the tree would still make him feel the overwhelming sense of guilt he has carried since Finny's death. He came expecting it to look like artillery but instead he found a tree that looked so very much like all the other trees and so very withered with age. Seeing it looking withered, even humbled, by age makes him understand that "nothing endures, not a tree, not love, not even a death by violence," and, most importantly, not his sense of guilt (p. 3). We can see Gene's readiness to let go of his guilt when he starts heading back to the campus, as he describes, "I was drenched; anybody could see it was time to come in out of the rain" (p. 3). Here, his being drenched by rain metaphorically represents being drenched by guilt, and saying "it was time to come in out of the rain" metaphorically represents it being time to let go of his guilt.
Plus, his sense of guilt connects to the theme of complicated friendship because, had he not fought an internal battle within himself during his friendship with Finny, had his friendship with Finny been much more genuine, he never would have done anything to Finny that would have given him cause to feel guilty.