Mrs. Dubose is a cranky old lady who lives down the block from Jem and Scout. She sits on her front porch and taunts the children when they pass by. She is generally hateful and argumentative, except when Atticus disarms her by complimenting the flowers in her yard. The children believe Mrs. Dubose keeps a Confederate pistol under the shawl in her lap and isn't afraid to use it. Jem tolerates Mrs. Dubose until the day she verbally attacks his father: "Your father's no better than the niggers and trash he works for!" This pushes Jem over the edge of control. Shortly thereafter, he uses Scout's baton to destroy the blooms on Mrs. Dubose's prize camllias:
He did not calm down until he had cut the tops off every camellia bush Mrs. Dubose owned, until the ground was littered with green buds and leaves.
As punishment, Jem is forced to read to Mrs. Dubose every day until she dies after a few weeks. Only after her death, does he find out that she was breaking an addiction to morphine so that she could "die free." Jem's reading to her had helped Mrs. Dubose get through the afternoons as she endured her suffering as she slowly withdrew from the drug. From this incident, Jem learns a lesson in real courage, as Atticus explained it:
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. It's when you know 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. Mrs. Dubose won, all ninety-eight pounds of her. According to her views, she died beholden to nothing and nobody. She was the bravest person I ever knew.
The kind of moral courage Jem learned from Mrs. Dubose helped him understand, later, his father's courage in defending Tom Robinson.