A good thesis, or overall main idea, for Cynthia Ozick's short story "The Shawl" is that physical and mental oppression could drain the life out of a person, but no oppression would never drain the soul out of a person's life.
In this story, we find a woman Rosa, who is suffering the worst and most unfair punishment possible: Not only is she in a life or death situation due to her being Jewish, but she also has to defend the life of her child and keep it under rigorous secrecy. At the same time, she must struggle against the elements of survival: Food, weather, shelter, safety. She has none of that, and neither does her child, or her teenage niece, Stella.
However, even under these desperate conditions, her mind, which is a reflection of her soul (as the author seems to propose), reaches out to something higher than reality: She imagines things and allows for her imagination to run wild. It is the only way to allow for the cruel and evil nature of reality to be less painful. Perhaps it could also make reality become less real, and more palpable under the possibility that, maybe, everything is merely a fantasy. After all, who could possibly be sane enough to tolerate such pain? Yet, even then, nothing changes, but neither does Rose.
Therefore, the use of the mind and the imagination to attempt to suppress the impact of tragedy is sometimes our last resort to maintain our sanity. Even when we see the faraway lights of an incoming train, it may be possible to find succor in pretending that they are merely guiding lights at the end of a dark tunnel. Even at the end, Rosa had to use her mind as a protector when she sees her daughter being cruelly killed by the Nazis. It is certainly her use of her mind what slightly prevents a full breakdown of her body.