to recollect his past memories of the summer session when he was sixteen years old.
A, separate, peace - Wikipedia
Chapter 2: Finny is an anomaly at Devon; he is a big Brother Media Essay good student and athlete, but also a charming, likeable rule-breaker. Gene is normally a conservative, conformist type person, but around Phineas, he consents to break the rules more often. Gene reassures him that it was some blind unexplainable thing that made him do it, and it had nothing to do with hate or any ill-will against Finny. Meanwhile the boys are all dealing with the fact that it's 1943 and they would rather enlist in the military than waste their years studying. Gene had finally matured from an insecure child to a self-accepting adult. Back at Devon, things continue to heat. Phineas personally tries to take over and control him. Phineas was powerful in many ways: his strength, his spontaneity, and, most of all, his love. Phineas might have rather enjoyed the punishment if it was done in some kind of novel and known way (p.20). Brinker obviously doesn't agree. Gene is horribly guilt stricken and meets with Finny before his operation. Middler had dared to do the unthinkable, vaulting off a tree to land in a shallow river.
Gene feels that enlisting will give him a sense of purpose. Phineas pulls away from his friends because of their fascination with the war. Gene is introduced to Brinker's dad, and says that he has joined the Navy. Up in the tree, as Finny ventures out on the limb ahead of his roommate, Gene "jounces the branch." Finny falls, rather than leaping forward, and thus lands on the hard ground instead of in the water.