Apophthegm: chiefly British variant of apothegm: noun \ˈa-pə-ˌthem\
: a short, pithy, and instructive saying or formulation : aphorism
How many, many questions must also have gone unanswered. Holmes was at times blood brother to the Sphinx. There is a bit of dialogue that is in nearly all the tales. "You have a clue?" asks Watson eagerly. The answer is immortal: "It is a capital mistake, my dear Watson, to theorize before one has the facts." If one were called upon to find in literature the best inscription for a tombstone, it would be Holmes's cautious apophthegm. Watson should bargain for it on his grave. For Holmes's tombstone--"Elementary!"
But there can be no grave for Sherlock Holmes or Watson...Shall they not always live in Baker Street? Are they not there this instant, as one writes?...Outside, the hansoms rattle through the rain, and Moriarty plans his latest devilry. Within, the sea-coal flames upon the hearth, and Holmes and Watson take their well-won ease. ...
So they still live for all that love them well: in a romantic chamber of the heart: in a nostalgic country of the mind: where it is always 1895.
(from Vincent Starrett's "The Private Life of Sherlock Holmes")