After the trial of Tom Robinson and his unjust conviction, the naivete of Jem is lost, and the innocence of Scout is certainly diminished as is that of Dill. In Chapter 22, at the trial's end, Jem finds himself in tears, as Dill has been earlier when Mr. Raymond says of him,
"Things haven't caught up with that one's instinct yet. Let him get a little older and he won't get sick and cry. Maybe things'll strike him as being--not quite right, say, but he won't cry, ot when he get a few years on him."
Indeed, things are "not quite right" for Jem, who mutters on the way home, "It ain't right"; later, with great indignation, he asks his father, "How could they do it, how could they?" Clearly, Jem is disillusioned. He reflects,
"I always thought Maycomb folks were the best folks in the world, least, that's what they seemed like."
And, Dill becomes cynical; he declares that he is going to be a clown when I grows up:
"There ain't one thing in this world I can do about folks except laugh, so I'm gonna join the circus and laugh my head off."
Once the children are home, Atticus talks to Jem, explaining how the society is set up, an arrangement that causes reasonable men to "lose their heads." He also explains how there was some consternation in one man's mind, a fact that gives Atticus hope.
After talking with his father, Jem attains some maturity, as does Scout who listens. Certainly, Jem's faith is people is shaken, but the words of Miss Maudie about the integrity of his father encourage Jem and his sister. Truly, it is a much more mature Jem and Scout who now understand the weakness and foibles of human nature.