JEM AND NATHAN RADLEY. One of Jem's earliest discoveries about adult deceit comes when he discovers Boo's brother cementing their secret knothole. Nathan tells Jem that the tree is diseased, his reason for the use of the cement. When Jem questions Atticus, Atticus tells him to look for himself: The tree is perfectly healthy, he tells Jem, who immediately realizes that Atticus is being straight with him and that Nathan has lied. He has sealed the knothole only to prevent further communication with Boo.
JEM AND THE LYNCH MOB. Jem discovers that some of Maycomb's citizens are not the "best in the world." Though Jem may not have understood the group's true intentions, he did recognize that they would have harmed Atticus if necessary.
JEM AND THE JURY. Jem is distraught following the guilty verdict. He recognized that Atticus proved his case and that Tom could not have been guilty. The jury's guilty verdict makes Jem wonder about the jury system as well as the goodness of his neighbors in Maycomb.