The allegory of homelessness
This story is about a character whose story is defined by his inability to find work during the Great Depression. The homelessness that grips him isn't a reflection of his work ethic, but rather, it is circumstance that makes work hard to find. This narrative features one of the most classic depictions of homelessness in all literature—a train-riding hobo crossing the country. William Music is living proof that not every homeless person is homeless by their own doing.
Mrs. Ella Bone
In Music's life, Ella Bone serves as an archetype by reaching down into his life and offering him a helping hand. She is a pivot point in his story, offering him a new path forward in life. Now he doesn't have to struggle to no avail. That being said, she can't offer him the job of his dreams or anything, but still, the mercy she shows him stands as an archetypal reminder that humans depend on each other. Music is saved by an invitation to community.
The coal mines
The coal mine is a symbol for the underworld. Anyone who knows about Kentucky coal mines can tell that these are not the jobs most people would want for themselves. The employees are unground, often in caves or mineshafts, often without a way to make their lives different or better (hence the push to unionize). Their work is destructive to their bodies, both because they breathe coal dust and because the manual labor is often done un narrow passageways that prevent them from standing up straight. This makes the labor a strong symbol for life in survival mode.
Hardcastle as unhealthy power
Hardcastle's depiction of power is highly symbolic. He is a person who established his power by force and fear, which is increasingly evident as the union gains traction. As they push him to his breaking point, he becomes more intense and violent, often ruining people's lives without warning, just for the rumor of union sympathies. His story shows how such kinds of power are self-defeating, because the union wins traction when the workers see his escalating temper.
The labor union
The symbolism of the workers union is complex, because many of the people who end up on strike are people whose political beliefs don't support labor unions, but in this particular case, the boss's aversion to unions has led the company down a dark path where the workers are forced to work at gunpoint. That means the union is absolutely necessary, because the boss is shown for his true colors and the unionizers are right—at least about him.
