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Though unseen until the final pages of the novel, Boo Radley serves as a major character throughout the entire novel, and is the central focus of Part One of To Kill a Mockingbird. Boo serves many purposes, especially to several of the primary themes that run throughout the novel. Jem and Scout are first afraid of Boo because of all of the stories and rumors they have heard about him. After the mysterious gifts begin to appear in the knothole, they finally come to realize that he is not the bad person of local legend; he proves to be kindly and protective, even before his heroic intervention with Bob Ewell at the end. Boo's change in the minds of the children is one of the examples of Harper Lee's theme of ignorance vs. knowledge, one that is mirrored later in the character of Tom Robinson. Both Boo and Tom are reflected in the theme of prejudice vs. tolerance. Boo's supposed mental instability does not sit well with many of his neighbors, and they do not treat him sympathetically. Boo is also a symbol of the innocent human mockingbird in the story, who is the butt of jokes and terrible slander, and presumed guilty of all sorts of gruesome crimes. Boo's appearance at the end also helps the author to tie together the two parts of her story, saving the children from Tom Robinson's accuser, Bob Ewell.