There has to be a good ethos when writing and the ethos in this case comes from the narrator, Dr. Watson. He is the normal person; he’s smart, logical to the terms of the greater society, and humble. He sees people for the more obvious qualities they pose and sticks to simplicities. More people are going to be able to relate to this character and see Mr. Holmes in a way that makes him seem odd but spectacular. To show the odd greatness of the ingenious hermit, it’s best to show him from a different perspective--Dr. Watson’s. Sherlock Holmes is a man described by Dr. Watson as “relentless, keen-witted, a ready-handed criminal agent, and presenting extreme exactness and astuteness”-- (the intellectual ability to penetrate deeply into ideas).
