How do the events in the final chapters of "To Kill A Mockingbird" explain the first sentence in the whole novel?Harper Lee's "To Kill a Mockingbird"

In the first sentence of "Two Kill a Mockingbird," the motif of learning experiences is introduced with the novel as Bildungsroman, or a novel of maturation.)  With the allusion to Jem's having his arm broken when he was thirteen years old and with the allusion to Dill's first giving the children the idea of making Boo Radley come out [of his house], the reader is lead through the narration of all the events leading to the attack upon Jem that caused his arm to have been broken.

From Atticus Finch's taking on the defense of the poor, innocent Tom Robinson, to the pranks of the children, then their communication with Boo in the knothole of the tree, to the trial of Tom and interrogations of Bow Ewell, the events of the last chapter all converge upon the walk home of Jem and Scout.  After Bob Ewell has tried to break into Judge Taylor's house and attempted to intimidate Hellen Robinson, there is foreshadowing of his act of revenge against Atticus.  As the children return from the school pageant, a dark figure attacks them.  As Jem and the dark figure struggle, a third figure appears; the children do not recognize him in this darkness, but it is at this point in the novel that the Tom Robinson/Bob Ewell theme comes together with the Boo Radley theme.

As Scout stands on the Radley porch, Scout has her maturing moment as she realizes the moral truth that the Radley place has no childish mystery about it at all.  The town looks the same from it as it has from her own porch.  And, with Scout's discovery that Boo is a kind person, she has developed from a little rascal to a young lady who was just escorted from her home.  She now understands her neighbor and realizes the disastrous effects which would occur by bringing Boo to trial. This maturity is measured against Atticus's mistaken conclusions about Bob Ewell and Heck Tate's view of the murder.  In actuality, Scout understands more than does Atticus about the implications of Boo Radley in the incident. Scout's growth is clearly evident at the conclusion of Harper Lee's novel.