In Chapter One, George explains why he and Lennie aren't like the other itinerant ranch hands who have no future.
With us it ain't like that. We got a future. We got somebody to talk to that gives a damn about us. We don't have to sit in no bar room blowin' in our jack jus' because we got no place else to go.
George then describes the farm they hope to have some day. This section shows two themes: friendship and the elusive American dream.
George constantly warns Lennie what not to do but there are times when Lennie feels pressured in social situations. The swamper tells George that Curley is always looking for a fight, foreshadowing what is to come. "Curley's like a lot of little guys. He hates big guys. He's alla time picking scraps with big guys."
In Chapter 3, Candy tells George, "I ought to of shot that dog myself, George. I shouldn't ought to of let no stranger shoot my dog." This is significant because of what George feels forced to do at the end of Chapter 6.
In Chapter 4, Crooks asks to come work on Lennie's and George's farm if it should ever manifest.
He hesitated. ". . . If you . . . guys would want a hand to work for nothing--just his keep, why I'd come an' lend a hand.
After being scolded by Curley's wife however, Crooks tells Candy to forget that he offered. Like Lennie, Crooks is a social outcast and this is a moment when he gets his hopes up but then, discouraged, he once again accepts that he is the outcast.
The crucial moment in Chapter 5 is when Curley's wife invites Lennie to feel her hair. As he'd done with the puppy, he couldn't control his emotions or his own strength.
"Don't go yellin'," he said, and he shook her; and her body flopped like a fish. And then she was still, for Lennie had broken her neck.
The most dramatic moment in Chapter 6 is when George brings himself to do to Lennie what Candy could not do to his dog. Slim is wise enough to realize that George had to kill Lennie and Slim is George's only source of consolation. Then, symbolically, Slim leads George away from the Salinas River, George's and Lennie's safe haven and the place where the story began.
Slim said, "You hadda, George. I swear you hadda. Come on with me." He led George into the entrance of the trail and up toward the highway.