One of the major themes of to kill a mockingbird is that you shouldn't kill something that is innocent. This is first shown when Atticus has a conversation with Jem when he says "'Remember it's a sin to kill a mockingbird. ' That was the only time I ever heard Atticus say it was a sin to do something, and I asked Miss Maudie about it. 'Your father's right,' she said. 'Mockingbirds don't do one thing but make music for us to enjoy…but sing their hearts out for us.". In the novel the mockingbird represents Tom Robinson who was falsely accused and later killed. This novel has so much depth and meaning to it just to get the simple point across that is a sin to kill something that is innocent.