A literary “theme” can take different forms. It can be the dominating idea or ideas of a text, but it can also be what the writer wishes to say about that idea—his message or moral, if you will.
In Langston Hughes’s “Thank You, Ma’am,” I’ll focus on the theme of respect. When Roger attempts to take Mrs. Jones’ purse, he’s only thinking of himself and what he wants. He has no respect for her or her belongings and it may be argued that he shows no respect for himself, either. She reacts by choosing to not treat him like a common thief, but with kindness and concern—with respect. She goes so far as to offer him dinner, but to not ask why he is on the streets alone and why he hasn’t eaten, in so doing respecting his individuality and his boundaries. In the course of the evening, when she goes behind a screen to cook, leaving her purse near the boy, he “took care to sit on the far side of the room where he thought she could easily see him out of the corner of her eye,” having discovered that “he did not want to be mistrusted now.” She showed him respect and he found himself wishing to be deserving of it.
He asks if she needs him to run to the store for anything, and she says not unless he wants some sweet milk to drink, but she was just going to make cocoa. He agrees that cocoa is fine. This simple exchange marks a change in the trust they have in one another. Before, his thoughts were bent on escape and she knew it. Now, he offers to run an errand—and opportunity for him to escape, possibly with her money—and she gives him the opportunity, but he turns her down. This trust established, the respect between them and in particular, his self-respect deepens.