How does the setting of Mice and Men influence the book's thematic development?

Of mice and men is set in the town of soledad, meaning lonely in spanish. Light is also an important factor in the book. Light is often seen as hope, so there are several times Curleys wife blocks off light, for example in "the rectangle of sunshine in the doorway was cut off", while near the end of the book steinbeck writes that "the light climbed out of the valley", symbolising the end to Lennie and George's dreams.