Since "To Kill a Mockingbird"'s is a Bildungsroman, or "novel of maturation," Harper Lee's novel has several lessons. One such lesson is that of social justice with the key focus, of course, upon racial justice which Atticus Finch seeks to establish by defending Tom Robinson. In addition to this justice, Atticus wishes to instill in his children a sense of respect for everyone, no matter how "odd" he/she may be. Jem's father has him read to Mrs. Dubose, whom Jem perceives as mean, so that he may come to understand the old woman. Atticus forbids the children to build games around the story of Bo Radley and to respect the Radley property.
From both Mrs. Dubose and Bo Radley, the children learn about courage. For Mrs. Dubose weans herself from morphine before she dies so that she can meet death with courage. And, reclusive Bo Radley braves the outside of his house to rescue Jem and Scout from the attacks of Tom Ewell. Of course, Atticus Finch himself sets a stellar example for his children of courage as he defends the young black man despite the intimidations of the community. In fact, throughout the novel, Atticus displays inner worth and strength as he faces every adversary, be he mad dog or an angry relative or neighbor.
The biggest thing people should bring from this book is how people should not be treated with prejudices or stereotypes no matter what their race, color, or gender is. People should also present themselves nicely in front of others they hate because in the end, those who do bad will have it reflect badly on them and their deeds will come swinging back at them in the end.
There is a rite of passage for the young children, in the end their lives will never be the same. They start the novel in innocence and slowly enter the brutal world of adult experience, where they quickly learn that it is a world with class, religious, and racial borders to overcome.
The biggest lesson to be learned in this novel is to attempt to be more like a child at heart, to let go of prejudice, to reduce ignorance and to good on to others.