How's courage defined in the novel To Kill A Mockingbird?

Courage comes in many forms in this novel. One of my favourite parts is when Atticus discusses the "nasty" Miss. Dubose with his children. Atticus says,

"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."

Atticus is talking about 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.