The descriptions of Mrs. Jones’s actions make her seem large and powerful.
“Thank You, M’am” is the story of a young boy who robs a woman, but gets quite a shock when she decides to take him home instead of giving him her purse. Mrs. Jones is repeatedly referred to as “large” in the first paragraph, but it is the descriptions of what she does that make her seem large and powerful. Consider what she does when Roger attempts to steal her purse, and instead she knocks him down.
The large woman simply turned around and kicked him right square in the blue-jeaned sitter. Then she reached down, picked the boy up by his shirt front, and shook him until his teeth rattled.
Repetition is a powerful literary term, and so is simplicity. Hughes uses both in this story, repeating the word “large” and describing the woman’s actions to help the reader understand the size of the woman and her power. It is not just her physicality, but the largeness of her personality that matters. She was able to stop a mugging and defend herself, and then have the generosity to intervene in the boy’s life.
Even her name, Mrs. Luella Bates Washington Jones, is large and powerful. She tells the boy that by putting himself in contact with her, that contact is going to last. She knows that he needs an intervention. Few women would have the guts or the generosity to do what she does. She demonstrates physical strength by dragging him in a “half nelson” back to her house, where she makes him dinner.
Mrs. Jones sees in Roger a boy who needs a mother figure. She comments on his dirty face, and makes him wash up before eating. Hughes emphasizes the point where Roger came under her influence.
[Whereupon] she turned him loose -- at last. Roger looked at the door—looked at the woman—looked at the door—and went to the sink.
The emphasis is Hughes’s. It shows that Roger decided to stay with the woman, even though he originally only intended to rob her. This demonstrates the strength of her personality. It is not because she is physically keeping him there. It is because he sees something in her, and he is curious. He wants to see what she is about. As he stays, they have a conversation, and he comes to see a mentor in her.
A story's main idea is the big idea, or theme, that the author wrote the story to show. The main idea of the story is that appearances can be deceiving. Roger seemed like a criminal, and Mrs. Jones seemed like a victim. Neither of them turned out to be what the other expected. Mrs. Jones took Roger in, and taught him a life lesson. She took an interest in him, and listened to him. Langston Hughes wants his readers to remember an important theme—people are not always what they seem.