John Knowles, in A Separate Peace, illustrates a young man?s internal struggle to understand adulthood and its realities. This struggle emphasizes a continuos jealous rage inside Gene, which in turn causes him to cripple and kill his ?best? friend. The theme of jealousy is woven carefully throughout the novel in Gene and Finny?s relationship. Gene?s inability to acquire the purity, perfection, and carefree attitude of Finny is portrayed through several significant events in the book. These events include Gene?s jealousy when Finny charmed his way out of trouble at Mr. Patchwithers tea party, Finny?s isolation and illusion that there is no war, and Gene?s compulsion to possess the physical grace of Finny.
Knowles displays what happens when adolescence confronts manhood and the fears that develop when change becomes a reality. Gene, Brinker, and Leper all become casualties of this change by convincing themselves that the enemy lies outside of them. For Finny, there is no reality, no rules, no enemy, and no war. Gene, jealous of the fact that Finny, in his world of no rules, can live life to the fullest during the war, lets this obsessive jealousy get the best of him.