In To Kill a Mockingbird, Harper Lee clearly suggests that there is a strong connection between a character's integrity and courage because, as Atticus tells his children in Chapter 11,
"Courage is not a man with a gun in his hand. It's knowing you're licked before you begin but you begin anyway and you see it through no matter what. You rarely win, but sometimes you do."
Since this determination to do what is right is especially exemplified through the characterization of Mrs. Dubose, Atticus Finch, and Boo Radley, in developing one's thesis about courage, the writer can demonstrate the character development of these three personages. For, in this characterization there is exemplification of the ways in which each character faces insurmountable odds, but exerts fortitude, nevertheless.
So, with a review of the actions of Mrs. Dubose as she fights her morphine addiction so that she can finish her life in awareness, and a review of the tremendous strength of character that it takes for Atticus Finch to defend Tom Robinson so that his children will not grow up with "Maycomb's usual disease," and an examination of the huge effort that is takes for the shy recluse Boo Radley to come to the defense of the children because of his love for them, the theme of courage can certainly be illustrated in To Kill a Mockingbird.