The most important lesson in the story is that you must always respect other people, no matter how different they are from you. They do what they believe is right according to their understanding of the world. You can let them act as they will without having to change your principle
Explanation:
I compressed the paragraph and fixed the format, as well as editing the answer itself a little. It's a little closer to what's good for the actual question, and I feel like it answers it better.
In the women's Bath, the narrator can see how her grandmother views the world when she bath together with her in the public bath
During that time, she understand more about her grandmother's point of views in every aspect of lives.
I think the most important lesson in the story is you always have to respect other people, no matter how different they are from you, they do what they believe is right and you can let them do it without have to change your principle