In 1887, Sherlock Holmes didn’t care at all about breadth of knowledge, and wasn’t interested in amassing esoteric information. He was ignorant of many things, focused purely on his rather narrow interests. He didn’t even know, for example, that the Earth orbits around the Sun:
“It is of the highest importance not to have useless facts elbowing out the useful ones … you say we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or to my work.” – A Study in Scarlet
But then something changed. In 1915, Holmes is reported to have said:
“Breadth of view, my dear Mr. Mac … the interplay of ideas and the oblique uses of knowledge are often of extraordinary interest.” – The Valley of Fear
And then in 1927:
“I hold a vast store of out-of-the-way knowledge … my mind is like a crowded box-room with packets of all sorts stowed away therein – so many that I may well have but a vague perception of what was there.” – The Adventure of the Lion’s Mane
The latter two statements clearly contradict the first. Holmes has moved from a tightly focused schema of knowledge to one that is all-encompassing and places value in ‘out-of-the-way’ information.
What are we to deduce? Did Holmes change his mind, and his methods? Did he receive a serious bash on the head at the Reichenbach falls? Did Watson misunderstand or miscommunicate some (or all) of these moments? Are we then to consider him an unreliable narrator?
Perhaps this is the more interesting question: Why did Arthur Conan Doyle switch tacks?
Is an obsessively focused mind more convincingly capable of observation and induction in the investigation of crimes, or do we prefer the Renaissance Man of the late Holmes, whose holistic sense of knowledge enabled him to make unlikely connections?
I think these differences really caught my attention because they seem to mirror the choices we are asked to make – or, at least, the unconscious patterns we eventually fall in to – when it comes to knowledge. To become expert in any one area is usually predicated upon selective ignorance in a host of others. We might be impressed by someone with a vast range of information at their command, but how often would we call them a genius? Is it realistic to horde tidbits of esoterica on the basis that it might some day come in handy?
Simon Kaye PhD - Policy Research 
Fantastic post. I enjoy Sherlock Holmes quite a bit, but I never noticed this switch. It’s something to think about. Thanks for posting.
@Alison thanks for the kind words!
In playing the Game, there is actually a fairly simple answer. Holmes and Watson moved in together in January 1881 (A Study in Scarlet). They were, in those early months, January and February, strangers. “I was never a very sociable fellow, Watson, always rather fond of moping in my rooms and working out my own little methods of thought, so that I never mixed much with the men of my year,” Holmes tells Watson later in their friendship. So in that early winter of 1881, Holmes is looking for someone to share the rent, not conversation. When Watson tries to engage him, Holmes has replies sure to end small talk: “Upon my quoting Thomas Carlyle, he enquired in the naivest way who he might be and what he had done. My surprise reached a climax, however, when I found incidentally that he was ignorant of the Copernican Theory and of the composition of the Solar System. That any civilized human being in this nineteenth century should not be aware that the earth travelled round the sun appeared to be to me such an extraordinary fact that I could hardly realize it.” Holmes explains his position to Watson ending in what you quote above. Next, Watson writes, “I was on the point of asking him what that work might be, but something in his manner showed me that the question would be an unwelcome one. I pondered over our short conversation, however, and endeavoured to draw my deductions from it.” Unwanted conversation stopped, idle chit-chat ended. Of course, Holmes knows of Carlyle (“Are you well up in your Jean Paul?” Holmes asks Watson in The Sign of Four. “Fairly so. I worked back to him through Carlyle.” “That was like following the brook to the parent lake.”) and is is up on his Copernicus (“It was after tea on a summer evening, and the conversation, which had roamed in a desultory, spasmodic fashion from golf clubs to the causes of the change in the obliquity of the ecliptic, came round at last to the question of atavism and hereditary aptitudes,” Watson writes in The Greek Interpreter). The fact is, Holmes was always interested in increasing his store of knowledge. It’s just that in 1881, he wasn’t interested in increasing his number of friends, until that is he had seen that Watson was “someone…on whom I can thoroughly rely”.
Much has been made about Holmes so-called lack of Copernican knowledge. Holmes’ statement got this virtual stranger to leave him be. And Watson may have been taken in, at least temporally. What is more interesting, is how many others over the years have been fooled as well.
Thanks for this, James: a satisfying in-universe explanation. I do think it leaves the interesting question of shifting authorial intention open, however. I’m not sure it’s clear that Conan Doyle wasn’t rather haphazard, or at least prone to changing his mind, when it came to Holmes’ methods and approach to knowledge.
Indeed Doyle was haphazard, at least in what he considered his lesser work. He heavily researched his historical fiction, filling numerous notebooks with facts of the era in question before writing a word of his novel. Doyle wrote A Study in Scarlet in 1886 and unsuccessfully sent it to publishers. Lock, Ward and Co. offered Doyle a measly £25 for all rights in September 1886 and held on to it for more that a year until it saw the light of day in Beeton’s Christmas Annual of 1887. It was in Doyle’s mind a one-off. Even with 1890’s The Sign of Four, Holmes and Watson were one-shot characters. Very few people had read A Study in Scarlet and Doyle had to re-introduce the characters to the public in Sign as if it was their first meeting with Holmes. It wasn’t until the Strand Magazine came into being in 1891 that Doyle even thought of making Holmes a serial character. I doubt that Doyle consulted Study or Sign, but just went with what he remembered of Holmes and Watson, resulting the the contradictions that Sherlockian scholars argue over to this day.
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