Oh I didn't mean you were one of the clueless youngsters I imagined! Your comment just made me to ponder and muse about how references work in our minds hence my hint at Borges who used to say that "every writer creates his own precursors".

And yes Moriarty is mentioned several times but appears only in two stories, I think. He was mostly a plot device to get rid of Sherlock Holmes, but the readers didn't accept it.