In Of Mice and Men, freedom isn’t so much a central point as it’s a constant and silent contrast to confinement. Confinement, like isolation, seems to be a state of mind. Though the men on the ranch work outside, socialize with each other, and are free to leave whenever they please, they still feel locked into their lives. There’s something hanging over them that stops them from feeling free. In the case of Lennie and George, they’re tied down by their need for money; Curley’s wife is limited by being a woman; and Crooks by his race. Except when they’re caught up in the intensity of the dream, most characters seem more focused on bemoaning their confinement than planning for or achieving their freedom.
The feeling of confinement in Of Mice and Men is influenced by the "grass is always greener someplace else" phenomenon. George would love to be free to have a settled piece of land, and Whit fantasizes about getting off the ranch, but this is simply the "grass is greener" in action.
Confinement is the defining force in the novella. All the characters are in some way trapped, either by their circumstances or who they are. Their lives are simply processes of becoming comfortable with those traps. The only one who escapes this is Lennie, not only because he is killed, but because he faces his inner demons before he dies.