Loneliness is a prevalent theme throughout the novella. Each character represents the theme of loneliness in his or her own way. Every character, with the exception of Slim, is lonely - George is alone at the end of the novel after he kills Lennie (he sacrificed being alone for the saving grace of offering Lennie a mercy killing); Crooks is segregated and aloof, alone literally and figuratively in the world of white men...the only black man on a ranch full of white ranch workers, books his only comfort and not much at that (books cannot talk back); Curley's Wife is alone and friendless, which is why she stubbornly flirts with the men on the ranch, as she is alone in her own marriage to Curley who is possessive, cruel, and jealous; Lennie is alone with only George to understand him; Candy is alone once his poor old dog is shot, left to worry constantly about how useless he is in his old age and with his handicap; and throughout it all, George and Lennie are the exception to loneliness in that they travel together, share a dream, and look out for one another.
The title of John Steinbeck's book suggests that the main theme has to do with the inability of uneducated and unskilled farm workers to escape from a life of toil and an old age of poverty and misery. The title is taken from Robert Burns' famous poem "To a Mouse" in which the speaker says (to paraphrase): "The best laid plans of mice and men are often disappointed by unforeseeable events." George and Lennie have a dream about owning their own little farm where they can raise almost everything they need. But in the end everything goes wrong and George ends up shooting Lennie. They are not the only ones who dream of independence and freedom from virtual field slavery. Other characters comment that there are thousands of men who have the same dream but none of them ever realize it. These men are all the "mice" alluded to in the title. The old man called Candy buys into George and Lennie's dream, and he too is disappointed when it fails to materialize. It is worse for him because he is old and their dream represents his last chance.
Another main theme, closely related to the one about owning a subsistence farm, has to do with the hard lives of itinerant farm workers in California. An essay on this subject could simply describe most of the conditions and incidents Steinbeck used to illustrate how these "bindlestiffs" had to live. They didn't even have hot showers after a hard day's work, but washed in metal basins with cold water. They slept on burlap sacks filled with barley. There was never quite enough food, and the food must have been bad. The work was excruciating and lasted for long hours in the hot sun. The pay was extremely low, so they were like slaves tied to the ranch for food and shelter. When a man got too old to work he was cast out. This specter haunted Candy and Crooks and was beginning to haunt some of the middle-aged workers such as Carlson. Implicit in this theme is Steinbeck's message that the federal government ought to pass laws to protect workers from such injustice, and that the workers themselves ought to organize and fight for such legal protection. He brought this out more fully in his best novel The Grapes of Wrath.
The general public was not aware of the living and working conditions of itinerant farm workers in 1937. Steinbeck hoped that by calling attention to the ugly truth he could help to bring about change. He wrote the book and immediately turned it into a script for a stage play which was produced in New York the same year the book was published. Both the book and the play were financially successful and influential in swaying public opinion. Steinbeck quickly became one of the most famous authors in America, and his books are still popular in the 21st century.
You could write about the relationship between George and Lennie--but they are only imaginary characters used to represent many thousands of real people.
One big theme in the book Of Mice and Men is Idealism vs. Reality. The main characters, George and Lennie, dream of having a farm of their own, but that isn't as easy to achieve as it may seem. They repeatedly discuss this dream that they have but in reality they would never get it in their circumstance. It was difficult to find a job and save up money in that time period.
Another big theme is loyalty and friendship. George sticks with Lennie even though he gets them into trouble, due to his mental disability. He cares for Lennie and wants to look after him, making sure he knows he is not alone. Neither of them had family or a real place to go; they only had each other.
I think the Main themes of Mice and Men are as follows:
Solitute contrasted with friendship;
Friendship; they were migrant workers, they did not have time to make friends because of the Great Depression, except for Lennie and George.
Loneliness: Characters Crooks (black), Curley's wife (woman, Candy (old age), George (his fate. Other elements - Soledad (name of place suggests solitude), solitaire (loneliness)
Broken dreams: George (buying land), Curley's wife.
It is important to note that the novel ends as it begins. Dreams are just dreams. The fact that Lennie always got into trouble indicates what's going to happen. (Make reference to Robert Burns' poem).
'The best laid schemes o'mice and men
Gang aft aqley (often go wrong)
And leave us naought but grief and pain
For promi'ed joy#
Dreams only bring sadness and pain instead of happiness.
However a dream keeps you going on like Lennie did to keep his and George's dream alive. Furthermore Candy changes into a confident person and believes in his dream (Refer to pg 78 2nd paragraph)
Discrimination: Reference to the old days during the American Depression: racism, ageism, sexism, disability (Crooks, Candy, Curley's wife).
Violence: both physical and verbal and as a result of loneliness.