Willa Cather, "A Wagner Matinée" (1904) from Willa Cather: Stories, Poems, & Other Writings:
A guy living in Boston gets a visit from the aunt who helped raise him out in the culture-less wilds of Nebraska; this aunt is very musical and from Boston originally, so they go see a performance of some Wagner music, which deeply affects her. As the note at the LoA site says, Cather got in some family trouble for this story, since they didn't like their Western home depicted as being culture-less wilds--and after reading the story, I'm not sure what else there is here.
It's one of those stories where the narrator watches someone else have an experience, which means that the story is fairly plot-free, but also not super interesting on a character-level: we don't get to feel that experience first-hand--what exactly is Aunt Georgiana realizing when she listens to these songs?--and the second-hand experience comes through a character whose defining feature is "guy who lives in Boston now."
Also, so much of the story is spent describing the Wagner, that I think I would have to mark as correct any student essay which described the theme of this story as "you should really listen to Wagner."
This is a short note, which is a shame for my 60th post. I'm now currently 1/3rd of the way through the 180 Stories of the Week. Of course, for every seven stories I do, they add another--so I should be done in 20 weeks.