In the final chapter of To Kill a Mockingbird, Scout walks Boo Radley home after he has rescued Jem and her from the harm that Bob Ewell attempted. As she stands on the porch of the Radley's, Scout surveys her neighborhood from a new point of view, that of Boo Radley:
Atticus was right. One time he said you never really know a man until you stand in his shoes and walk around in them. Just standing on the Radley porch was enough.
For Scout, the realization comes that Boo has, indeed, been a mockingbird--one who has never caused anyone harm, but also one who has been judged by the "songs of others." That is, she realizes that others in town had put "songs" into Boo's mouth that were imitations of their judgments rather than what Boo had actually done. When she returns home, Scout tells her father,"Atticus, he was real nice...." Atticus comments, "Most people are, Scout, when you finally see them."
At the end of Chapter Thirty, Atticus and Sheriff Tate are discussing Bob Ewell's death. Atticus believes that Jem was responsible for killing Bob, but Sheriff Tate disagrees. Tate implies that Boo Radley was defending the children and was responsible for Bob's death. However, Sheriff Tate says that he will tell the community that Bob fell on his own knife so that Boo Radley will not receive unwanted attention from the community. Sheriff Tate tells Atticus that it would be a sin to force Boo into the limelight given his reclusive, shy nature. When Atticus asks Scout if she understands the situation, she tells him, "Yes sir, I understand . . . . Mr. Tate was right." Atticus then asks Scout what she means, and Scout says, "Well, it'd be sort of like shooting a mockingbird, wouldn't it?"
Scout metaphorically applies Atticus's earlier lesson regarding shooting mockingbirds. Scout understands that Boo Radley is a symbolic mockingbird, which means that he is an innocent, defenseless being. Casting Boo Radley into the community's limelight is essentially the same thing as shooting a defenseless mockingbird. Both the mockingbird and Boo Radley are innocent, harmless beings that do not deserve to be abused or hurt by others.