The overriding themes in Of Mice And Men are those of the American dream and the theme of friendship and loyalty between the characters, especially between George and Lennie.
The fragility of these dreams is what Of Mice And Men is based around. These themes and relationships are shown throughout the book in a number of ways and are added to by the use of language and structure but particularly imagery.
The imagery used is mostly animal imagery. Steinbeck uses animal metaphors and similes to strengthen the descriptions of the particularly important scenes and give dialogue or the actions made by the characters more emphasis. This animal imagery is used many times throughout the book, each time in a different way and lending a different effect to the passage.
In one section of the book, (p 90) Curley is described "flopping like a fish". This not only makes him seem inferior to Lennie but makes him seem inferior to man. His status is lowered from a powerful man to a small squirming fish. A very similar simile is used later on in the novel where Curley's wife is killed she is described: "her body flopped like a fish". This similarity takes two people with power of some kind; Curley's being the power over the other ranchers who he tries to intimidate and Curley's wife's being that she feels she has the power of seduction and also dominance over the only person on the ranch whose status is lower than hers as a woman, Crooks. It then shows how pathetic and dwarfed they are by Lennie.
This same effect is used to lower other people's status in the book however in some these places it is not as demeaning as the fish simile. At the same time at which Curley's wife dies, Lennie is made to seem like an animal. "He pawed" He is also made to seem clumsy by this, reinforcing the story that it was an accident and that he is trying to be gentle, with the