I good detective never misses the small clues, no matter how insignificant they might seem to those of us who are not detectives.

“The affair seems absurdly trifling, and yet I dare call nothing trivial when I reflect that some of my most classic cases have had the least promising commencement. You will remember, Watson, how the dreadful business of the Abernetty family was first brought to my notice by the depth which the parsley had sunk into the butter upon a hot day.”

Sherlock Holmes in Arthur Conan Doyle’s The Adventure of the Six Napoleons From The Return of Sherlock Holmes

Now, I wonder how the depth the parsley had sunk into the butter could have been useful in the Abernetty family case? Not being a detective myself, I almost think Sir Arthur just make this up.