On Sherlock Holmes' breadth of knowledge

Sherlock Holmes' approach to collecting information is to only seek and store that which will be useful to him in the future.  In the second chapter of the first book in which this illustrious detective is introduced (A Study in Scarlet), his biographer and friend Dr. John Watson makes an inventory of Holmes' knowledge.  The list, reproduced below: (taken from Page By Page Books)

1. Knowledge of Literature. -- Nil.
2.              Philosophy. -- Nil.
3.              Astronomy. -- Nil.
4.              Politics. -- Feeble.
5.              Botany. -- Variable.  Well up in belladonna,
                            opium, and poisons generally.
                            Knows nothing of practical gardening.
6.              Geology. -- Practical, but limited.
                             Tells at a glance different soils
                             from each other.  After walks has
                             shown me splashes upon his trousers,
                             and told me by their colour and
                             consistence in what part of London
                             he had received them.
7.              Chemistry. -- Profound.
8.              Anatomy. -- Accurate, but unsystematic.
9.              Sensational Literature. -- Immense.  He appears
                            to know every detail of every horror
                            perpetrated in the century.
10. Plays the violin well.
11. Is an expert singlestick player, boxer, and swordsman.
12. Has a good practical knowledge of British law.

Watson is inspired to write all this after Sherlock admits that he didn't know that Earth revolves around the Sun, and doesn't really care about this because it has no impact on how he goes about his life.  I think he sort of pulling Watson's (and the reader's) leg here; I think he really does know about the solar system but just wants to demonstrate that it has no impact on the work he does, and he values his mental storage space so much that even something so personally insignificant should be stored and saved.

You don't always get to choose what you remember, though.  I find that, in the Annals Of My Memories,  a lot of real estate is devoted to trivia and tidbits of information that only might be useful to me if I go on a game show, like "Jeopardy!" or "Who Wants to be a Millionaire?"  I'd like to think that I've learned a lot from my experiences and have some worldly, practical knowledge as a result, but at this point I don't have such a focused and intentional bank of information pertinent to my field of study.  The only thing that Sherlock and I share ispoint number 10: facility with the violin.  But I think he'd be the better violinist.  Yes, he is a fictional character and therefore allowed to be as talented as he is, worthy of countless superlatives, but still I can't help but admire him.  His breadth of knowledge is one of the reasons why.