Everyone in life has to grow up sooner or later. They change from the childish ways and become an adult. Jeremy Atticus Finch grows up in the book To Kill A Mockingbird. He has significantly grown from a childish playful boy that he was from the beginning of the novel. To a more calm composed and mature figure.
Before maturity, Jem had a childish concept of courage. He believed that bravery was doing something that was dumb. Doing something because they dared you to do it. Scout said “Jem never declined a dare.” This is not bravery rather than stupidity. He preferred to be praised and loved than to think first. Which begs to believe that Jem does not only accept dares blindly, he does not think of the consequences of the dare. Or the safety of his self or others. He believed that he was the bravest of all three children which led him to commit ridiculous gestures of bravery. Such as touching the front gates of the Radley's house. So he could prove that he wasn't afraid of anything. This form of courage is not respected by the adults in Maycomb, evident from the response of Atticus when he heard that the children was causing trouble in the Radley's place.
However, upon maturity Jem gained a different kind of courage, a moral courage, which is to do what is right even if it is not popular, or even if it might anger those around him. He demonstrates this when he and Scout found Dill underneath Scout's bed in the middle of the night. His first reaction was to “does your mother know where you are?” This shows he is becoming more of an adult, and shows that Jem is finally rationalizing and perceiving the situation around him. He puts himself in other people's shoes.
Next, Jem has false perceptions of Boo Radley. “Boo was about six-and-a-half feet tall, judging from his tracks; he dined on raw squirrels and any cats he could catch, that's why his hands were bloodstained. There was a long jagged scar that ran across his face; what teeth he had...