What is example of diction in "of mice and men" by john steinbeck? why is this device important to the story?

Steinbeck uses simile and metaphors to add detail to the characters.  

"Slowly like a terrier who doesn't want to bring a ball to his master Lennie approached drew back and approached again.

This demonstrates how Lennie is like a puppy and a child.

"Well you keep 'way from her 'cause she's like a rat trap if I've ever seen one."

This shows how George is always having to look out for Lennie.  He has to warn Lennie about the boss' wife.

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"When he had finished combing his hair he moved into the room, and he moved with a majesty only achieved by royalty and master craftsmen."(Steinbeck 33)
This describes Slim moving with majesty and royalty; felt powerful, no one could make him otherwise. This is important because it adds to the development of Slim by describing how powerful he was compared to the other men on the ranch.

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