Every Sherlock Holmes story has at least one marvelous scene.
I think one or two of the later Holmes stories are among the best.
Everything in a story should be credible.
The incredible thing happens at the beginning of the story always, you notice, not the end. A Sherlock Holmes story is never a trick story.
I'm not a collector. I don't keep letters, or books, or souvenirs. But I do keep one copy of each translation of my books into a foreign language. Have you ever seen a murder story printed in Singhalese? Wow!