Why is both Finny's fall and Gene's visit to Leper's house considered the climax of "A Separate Peace?"
In a sense, there is a parallelism to Finny's fall and Leper's breakdown: As Brinker laments, Devon has lost two of its potential soldiers. Also, there is a rift in the solidarity of Devon, scholastically, athletically, and militarily. For, Finny was the 'superstar' of the school while Leper was the first to enlist in the Army, but both have lost their status of respect. Finny is broken physically and Leper psychologically.
When Gene visits Leper at his home in Vermont, he describes it as the first of his journey through unknown parts of America during the war. Reaching Leper's house is part of his "war," Gene narrates. When he arrives, Gene wonders from whom Leper has "escaped," as he wrote in his note to Gene. As he talks, Leper senses Gene's contempt for him and strikes back:
'You always were a lord of the manor, weren't you? A swell guy, except when the chips were down. You always were a savage undernaeath. I always knew it, but never admitted it.'
By revealing that he is aware of the truth of what has happened when Finny fell from the branch, Leper exposes Gene's feelings of that night, just as Leper's feelings are exposed. And, as Leper intimates, he has pleased himself by leaving the army, just as Gene has pleased himself by taking revenge upon Finny on the tree branch. Leper accuses Gene of "crippling him for life," as Leper has been crippled by the War.
In John Knowles's "A Separate Peace," both incidents with Finny and Leper are climactic because neither boy will be the same after their incidents. Indeed, they have been wounded--one in body, the other in soul--and have come to a turning point in their lives in which they are unalterably changed.