Answer:
For the characters in Of Mice and Men, dreams are useful because they map out the possibilities of human happiness. Just as a map helps a traveler locate himself on the road, dreams help Lennie, George, and the others understand where they are and where they’re going. Many dreams in the work have a physical dimension: Not just wishes to be achieved, they are places to be reached. The fact that George’s ranch, the central dream of the book, is an actual place as opposed to a person or a thing underlines this geographical element. Dreams turn the characters’ otherwise meandering lives into journeys with a purpose, as they take pride in actions that support the achievement of their dreams and reject actions that do not. Having a destination gives the men’s lives meaning. Indeed, when others begin to believe in the dream-space that George has created, it becomes almost realer to them than the farm they work at, a phenomenon illustrated by Candy’s constant “figuring” about how to make good on their fantasy.
Dreams help the characters feel like more active participants in their own lives because they allow them to believe that the choices they make can have real, tangible benefits. They also help characters cope with misery and hardship, keeping them from succumbing to the difficulties they face regularly. In their darkest moments, George and Lennie invoke their ranch like a spell that can temper their daily sufferings and injustices. George and Lennie almost always fantasize about the ranch after some traumatic event or at the end of a long day, suggesting that they rely on their dreams as a kind of salve. The dream of the ranch offers George, Lennie, Candy, and the others a goal to work toward as well as the inspiration to keep struggling when things seem grim.But by the end of the story, Steinbeck reveals that dreams can be as poisonous as they are beneficial. What George discovers—and what Crooks already seems to know when he scornfully spurns Candy’s offer to join him, Lennie, and George—is that dreams are too often merely an articulation of what never can be. In such cases, dreams become a source of intense bitterness because they seduce cynical men to believe in them and then mock those men for their gullibility. The workers’ love of Western magazines suggests just such a relationship to dreams
Each one scoffs at the magazines in public but manages to sneak furtive glances when no one else is looking, as if they secretly wanted to be the cowboy heroes of pulp fiction. No one seems to understand this bitterness better than Crooks, whose sullen self-loathing is never stronger than when he lets himself believe in Lennie’s dream, only to be brutally reminded by Curley’s wife that he is not entitled to happiness in a white man’s world.
Ultimately, the dreams of ranches and rabbits that George and Lennie treasure are the very things that undo them. Seduced by how close he thinks he is to realizing his dream, George fools himself into thinking that Lennie can mind himself and stay out of trouble when past events confirm the contrary. In the end, George does not despair at Lennie’s death because the ranch is forever lost to him, but rather because his friend—the one good reality of his life, the one reality that redeemed George from worthlessness—is forever lost to him.