Short answer: Slim uses his authority and common sense to quiet Curley, persuading him to lie and say his hand was caught in a machine so George and Lennie won't be blamed and fired.
- What happened: After Curley attacks Lennie and Lennie crushes Curley’s hand, the ranchmen gather around. Curley is humiliated and angry, so there’s a real risk he’ll tell the boss the truth and get George and Lennie in trouble.
- Slim’s intervention: Slim takes Curley aside and talks to him privately. Rather than escalating, Slim tells Curley to cover the real cause of the injury. He convinces Curley to say his hand got caught in a machine. That gives Curley a way to save face without ruining George and Lennie’s jobs.
- Why Curley listens: Slim is the most respected man on the ranch — his opinion carries weight. Curley is young, insecure, and embarrassed about being beaten; Slim offers him a face-saving story that lets him avoid further humiliation. Slim’s quiet authority and the practical suggestion make compliance the easiest option for Curley.
- Result: Because Curley agrees to lie about the cause of the injury, he does not tell the boss the truth. George and Lennie keep their jobs. Slim’s action protects them and also prevents a larger fight or trouble on the ranch.
- Why this matters: The scene shows Slim’s role as moral center and peacemaker on the ranch. It also highlights the precariousness of George and Lennie’s position — their fate depends as much on the goodwill of others (and social power dynamics) as on their own behavior.
In short: Slim uses his respected position, offers Curley a way to save face, and keeps the real story quiet, which prevents Curley from getting George and Lennie fired.