Sherlock was clever and secretive while solving a case. Prove this statement correct by using evidences.

Don't use te word clever, a genius indeed! Remember from the first book made by Sir Arthur Conan Doyle: The Study in Scarlet. He has keen eyes! He noticed the mud from Dr. Watson shoes and his fractured leg when they're at the hospital laboratory. Then he deduced that Dr. Watson is a Afghanistan soldier, a doctor soldier who has shot of a bullet (I forgot what type of bullet was) in his legs while in the middle of war. And now, he's on a vacation (if that's what you called in a soldier language), searching an apartment in London.