In Harper Lee's To Kill a Mockingbird, Lee uses a variety of literary devices in her writing.
In Chapter Six, Scout makes this oberservation:
Sometimes when we made a midnight pilgrimage to the bathroom we would find [Atticus] reading.
"Midnight pilgrimage" is a metaphor for taking a walk; specifically, we could probably consider this a hyperbole as well. It is doubtful that walking to the bathroom was as long or difficult as a pilgrimage, which took weeks or months to accomplish.
Another metaphor is: "Summer was everything good to eat."
The first line of the story is "foreshadowing:"
When he was nearly thirteen, my brother Jem got his arm badly broken at the elbow.
This sentence refers, of course, to the attack against the children at the end of the story. This statement does not take on true significance until the story reaches its climax in Chapter 28.
"Understatement" is used when Scout refers to the Civil War in Chapter One:
Simon would have regarded with impotent fury the disturbance between the North and the South..."
The Civil War, which "left his descendants stripped of everything but their land" could certainly not be described as a disturbance, except by a young girl like Scout, who is narrating the story.
Perhaps one of the most outstanding of the literary devices used by Harper Lee in the story is her "imagery." One famous passage in Chapter One is well-known:
Maycomb was an old town, but it was a tired old town when I first knew it...People moved slowly then. They ambled across the square, shuffled in and out of the stores around it, took their time about everything. A day was twenty-four hours long, but seemed longer.
Another example of Lee's imagery is found in Chapter Three, and is used to describe Burris Ewell when a cootie (head lice) appears in his hair. Scout recalls:
He was the filthiest human I had ever seen. His neck was dark grey, the backs of his hands were rusty, and his fingernails were black deep into the quick. He peered at Miss Caroline from a fist-sized clean space on his face.
The purpose of imagery is to write so vividly that the reader can visualize the image in his or her mind based on what the author is describing.
In Chapter 14, Scout uses a "simile" as she describes Dill when he hears his Aunt Rachel's voice:
He shivered like a rabbit.
Dill is not furry, with long floppy ears, but his response is similar to a rabbit being hunted: he began to shake. Two dissimilar things sharing similar characteristics is a simile.
"Onomatopoeia" is found in Chapter 28, as Scout describes the sound she hears from their pursuer:
Whoever it was wore thick cotton pants; what I thought were trees rustling was the soft swish of cotton on cotton, wheek, wheek, with every step.
There are several uses of onomatopoeia in this passage. (Remember that onomatopoeia is a word that stands for the sound it describes, like the "buzz" of a bee.) The words are: rustling, swish and wheek.