In Chapter 10 of Harper Lee's To Kill a Mockingbird, Atticus shoots a rabid dog. The background of this incident is actually the main theme of the novel. Before a school trip, Atticus tells his two children that to kill a mockingbird is a sin. The mockingbird, a beautiful and innocent creature, would have no agency over its own fate. The bird is a metaphor for Tom Robinson, the innocent black man whom Atticus defends in court. The conversation is in the context of Jem and Scout's belief that their father is a weak and feeble man. He is older than the other parents, wear eyeglasses, and has the demeanor of a kind and academic lawyer (which he is). He refuses to teach them how to shoot their air rifles, and instead talks of non-violence and peace. Jem and Scout wish he were "cooler," to use a modern colloquialism.
The shooting of the rabid dog is one of the many surprise moments in Lee's novel. When Calpurnia sees the dog, she calls both Atticus and Mr. Heck Tate, the sheriff of Maycomb county. She knows about Atticus's secret talent. The sheriff and Atticus wait on the abandoned street for the rabid dog, which is a suspenseful confrontation, especially for Scout and Jem. The sheriff hands Atticus his gun to kill the dog. It turns out that Sheriff Heck Tate knew all along that Atticus Finch was the better shot, and acted accordingly. Atticus was once known was "One-Shot Finch," but he has long since given up shooting. He hides this from people, including his children, because he values peace over this talent, which is based in violence and aggression. S
Scout and Jem are awed by this new version of their barrister father. Scout desperately wishes to brag to all her peers about Atticus "One-Shot" Finch, but Jem forbids her. This moment indicates how Jem is maturing. Scout, still very young and rambunctious, can only think of the shooting of the rabid dog as an exciting event. But Jem, who is growing up, begins to understand why Atticus hides the things he does and why he is the way he is.
The scene shows Atticus in a different light to the reader as well. The reader already knows that he is a good human being and a good father. He cares for his children and their moral and intellectual growth. This chapter adds a new layer of badassery to the figure of Atticus Finch.