In Harper Lee's novel of maturation, To Kill a Mockingbird, the motif of empathy is introduced in the words of Atticus Finch as he instructs his daughter Scout in the necessity of considering things from the point of view of others in Chapter 3:

"First of all,...if you can learn a simple trick, Scout, you'll get along a lot better with all kinds of folks.  You never really understand a person until you consider things from his point of view---until you climb into his skin and walk around in it."

In Chapter 31, Scout reiterates the words of her father as she stands upon the Radley porch:

Atticus was right.  One time he said you never really know a man until you stand in his soes and walk around in them.  Just standing on the Radley porch was enough.

From this vantage point, Scout senses what it has been like for Boo to have been the recluse he has; imprisoned inside his home, Boo has had only this small vision of the world.  Thus, his contact with the children has been magnified in importance and his loss of the medium of the knothole in the tree devastating.  Scout feels ashamed that she and Jem and Dill have made him the sport of their games as they have considered him a "malevolent phantom."  She now realizes the meaning of Miss Maudie's words that perhaps Boo chooses to remain inside.  Perhaps, the world is too much for the shy and sensitive man who has been so misunderstood by his own family.  Instead, he has vicariously experienced love and joy by viewing the interaction of children with each other and with their father. 

Scout's understanding now that she is mature gives her an empathy for Boo.  But, earlier as a smaller child, Scout has not felt anything for the "phantom"; her empathy for Boo then has been non-existent.  For, empathy only comes from maturity of the soul, a maturity that must be nurtured by those kind, understanding men such as Atticus Finch.