Willa Cather really seems to have dug "Paul's Case"—so much that, for many years, it's the only story she'd let textbooks or anthologies reprint. (source).
Before Willa Cather was a writer, she planned on becoming a surgeon. During this time she dressed like a boy and called herself "Wm. Cather, M.D." and "William Cather, Jr." (source)
Willa Cather was teaching high school high school in Pittsburgh, Pennsylvania when she wrote "Paul's Case." So, she had lots of first-hand knowledge to base the high school sections of the story on. (source)
Willa Cather on her favorite writers: "Well, I've never changed in that respect much since I was a girl at school. There were great ones I liked best then and still like—Mark Twain, Henry James and Sarah Orne Jewett." (source)
Cather was not a fan of the Aesthetic movement, at least not in 1895. She called it "the most fatal and dangerous school of art that has ever voiced itself in the English tongue…They were full of insanity." (source)