To Kill A Mockingbird is rich in descriptive language and sensory images. It is highly symbolic and Harper Lee has introduced the reader to characters and situations using literary devices to reinforce her message. Literary devices enhance the meaning of what is being said or described. They add a unique perspective to mundane or otherwise ineffective descriptions. One of Lee's intentions in this novel is to make the reader see the disabling effects of prejudice, injustice and bigotry as it exists in Maycomb County where narrow-mindedness and hypocrisy is the norm and where the people are oblivious to their own shortcomings.
Scout is the sole narrator and simile (in this case, making a comparison using "as...as") is a fitting way to explain her perception such as when she says that Atticus "could make a rape case as dry as a sermon" in chapter 17. Scout is explaining Atticus's capacity for seeing beyond the intense melodrama that would otherwise accompany this trial and prevent anyone from seeing the real truth. Unfortunately, despite the obvious truth, the jury will still find against the innocent Tom Robinson.
In chapter 17, metaphor and onomatopoeia are used. Metaphor uses a direct comparison of two completely different things and onomatopoeia uses the sound that is associated with an action to create intensity, and in this instance, both are used to stress how worthless and insignificant Bob Ewell really is. The distinction between the "booming" voice of the clerk of the court (onomatopoeia) and the "little bantam cock of a man," (metaphor) Bob Ewell, is evident and the reader cannot help but have an instinctive dislike of Bob Ewell.