Another lesson is one of conformity. Boo Radley refused to conform to his father's beliefs, and the result was that his father contributed to his isolation and pain. Nathan Jr. showed his willingness to continue that by cementing up the tree, but dangers of conformity is repeated through many different characters other than Boo.
Scout is berated for learning to read because it does not conform with the expectation that *school* should teach her that. She's different from her classmates; therefore, something's wrong.
Dolphus Raymond doesn't conform by having a family with a black woman, and he must pretend to be the town drunk to avoid a confrontation with racists who would otherwise see a sober white man as too good for a black woman.
Jem conforms to the norms at school and tells Scout that while they'll continue to play together at home, she'll see that school is just different.
Even the Tom issue can be seen in terms of conformity. Tom broke the norms of that society... he felt sorry for a white woman (which implied he felt superior to her). By doing this, he made himself a target for those who want to maintain the status quo (namely that blacks are inferior and cannot ever feel sorry for whites)
The theme that prejudice is an evil that can both injure and destroy people is found throughout the plot, in a variety of characters. With Tom Robinson it is prejudice in the form of racism. Boo Radley, on the other hand, is a victim of prejudice in that the townspeople believe all of the crazy stories swirling around Maycomb and assume they are all true; it turns out that he is not only NOT crazy, but a moral, kind and brave person. Another lesson to be learned is that people are not always what them seem - again, an offshoot of the pre-judging people without really knowing them or "walking in their shoes." Mrs. Dubose is a character who demonstrates that people are more than their outward behavior indicates they are. She was a woman living in great pain and not the horrid monster the kids thought she was. Through Atticus Finch, the reader (via Scout) learns that just because something is difficult doesn't mean it should be avoided. Atticus explains this to Scout in his attempt to make her understand why he is compelled to defend Tom Robinson.
The prejudice in Maycomb County was a sort of disease that afflicted even the "good" people. It spreads like a disease among the cattle. When Attics was forced to shoot the rabid dog coming down his street, it was a metaphor of Atticuss labors as a lawyer, trying to get ride of the disease of prejudice of Maycomb County before it infects others and does more destruction though out the county. As Atticus tells Scout , “you never really understand a person until you consider things from his point of view-until you climb into his skin and walk around in it" (chap3 , page 38)