Physical and mental impairments in Of Mice and Men serve to symbolize both the disfranchisement of the "bindle stiffs" and their tragic yearnings during the Great Depression, the setting of the novel. In Steinbeck's work of Social Realism, the dispossessed men of the narrative have little or no recourse against the fatalistic forces that work against them. For, Steinbeck perceives a tragic and problematic relationship between the itinerant workers and the land that they work, a relationship that he symbolizes with the physical and psychological impairments of the characters who live as solitary men outside Soledad and exist outside the real workings of agriculture.
While the characters George, Lennie, Candy, and Crooks are employed at the ranch, they are completely outside any of the real workings of the place and can easily be deposed from this ranch. Candy, for instance, worries constantly that he will be disposed of just like his old dog because he can no longer be useful in the fields after having lost his hand. Equally insecure is Crooks, whose back is broken; he inability to stand erect symbolizes his inability to be perceived and treated as a man because he is black. Lennie, as Steinbeck himself once wrote, "...was not to represent insanity at all but the inarticulate and powerful yearning of all men" as he repeatedly asks George to recite their dream of owning a farm themselves on which they can be independent. And, although Curley is the son of the boss, he, too, is impaired; his crushed hand symbolizes the absolute detachment of the large agricultural businesses from those who work on the land, another impairment to what Steinbeck held as the fraternity of men necessary for a successful society.
Indeed, the lives of the bindle stiffs of Steinbeck's Of Mice and Men lead lives of what Thoreau called "tragic desperation" as they are handicapped by the social realities of the Depression that have left them dispossessed and alone in an uncaring world of large business-like farms.