How does the following quote relate to "To Kill a Mockingbird"?"The book to read is not the one which thinks for you but the one that makes you...

Many book are written in such a way that the audience is told exactly how the protagonist changes and exactly how all events are to be interpreted.  The Scarlet Letter, by Nathaniel Hawthorne, is a great example of this.  The readers are told how each character learns his/her lesson.  In this book, however, that is not the case.

Take the narrator, to begin with.  A book that thinks for you will most often have an outside narrator who explains the actions of each character and what he/she is thinking.  However, in Mockingbird, we have a young girl as our narrator.  Scout doesn't understand much of what is happening around her.  For example, she doesn't understand at the courthouse that the men are there is raid the jail and lynch Tom Robinson.  The readers must infer that this is their purpose from the discussion they have with Atticus.  Scout also does not understand why the men go away.  We, as readers, must understand that seeing Scout has caused Mr. Cunningham to think of his own son, and to be ashamed of what hs is planning to do. 

Although Atticus provides some clear lessons for Scout, such as it is a sin to kill a mockingbird, it is the readers that are left to make the connections from this message to Tom Robinson to Boo Radley and beyond.  Through the eyes of a child, we see the world in which she grows up, and are left to draw our own conclusions.