Beyond the novel's interest in the themes of identity, guilt/justice and the problems of maintaining a state of innocence, Knowles' novel presents a resolution for Gene that can be read as a lesson or a moral.
Gene learns to accept himself as a separate person; responsible for his own actions and decisions. In his opening comments, Gene states, "The war was and is reality for me. I still instinctively live and think in its atmosphere."
By the end of the novel, Gene has found a way to his own peace and has come to terms with his personal war - one defined by his guilt regarding Finny and Finny's death.
"Gene has discovered that his private evil, which caused him to hurt Phineas, is the same evil—only magnified—that results in war."
Learning that he does not need to follow Finny's example and does not need to follow Brinker's example either, Gene discovers that he is free (and responsible) to choose his own path, his own attitudes, and his own values.
Gaining this insight is highly significant to the meaning of Gene's narrative and to the meaning of the novel. Ultimately, this is the lesson presented in the novel.