At the end of the novel, Atticus reads to Scout as she drifts off to sleep. How does the topic of the story connect to one of the novel's major themes?

There are a few ideas at play here. Firstly the Grey Ghost recalls their own Boo Radley. Like Radley the character of Stoner's boy was misjudged. Secondly the character, like Boo Radley, turns out to be a hero.