What is the significance of courage in To Kill a Mockingbird?

I think courage, in the context of the novel, means standing up for what is right even in the face of overwhelming opposition. Atticus defends Tom Robinson despite opposition from the white community. Also, Atticus teaches us that courage comes in other forms as well. Consider the cranky old Mrs. Dubose, an old lady who is a morphine addict. She has the courage to die sober, without the drugs she had depended on for so long. It is a very different type of courage than a man with a gun.

"I wanted you to see something about her (referring to Mrs. Dubose) - I wanted you to see what real courage is, instead of getting the idea that courage is a man with a gun in his hand."