It is sensational to take a new look at an old classic like “The Adventures of Sherlock Holmes.” The expression, “It is elementary, my dear Watson,” is quite popular. It is a quick way to sum up the notion that an idea, thought or concept is simple and easily understood. Easily understood that is if one is well read, experienced and well learned.
I missed the last part of the expression when I first read it many years ago. Many things were simple aka elementary to Holmes that were not elementary to Watson. Watson was trained as a medical doctor and was an intelligent man in his own right. Holmes was observant and continued to study a vast number of things and educate himself throughout his life. As a result, he had a large body of knowledge. This made many things completely unknown to most people, elementary to Holmes.