| Quote #1
"I owe you many apologies, my dear Watson, but it was all-important that it should be thought I was dead, and it is quite certain that you would not have written so convincing an account of my unhappy end had you yourself not thought it was true." (Empty House.34)
As on the X-Files, Holmes is like those conspirators who want/need people to "believe the lie." Though Holmes acts like he's a master actor, he clearly doesn't have the same faith in Watson's lying skills and as such ended up lying to his best friend out of necessity.
| Quote #2
"I have done no harm."
Though Holmes often lies for a good purpose, a lot of the criminals he encounters cause serious problems with their lies. In this case, Jonas Oldacre actually lied as part of a "joke" which turned out to be seriously unfunny.
| Quote #3
"Don't you think, Mr Cubitt," said he, at last, "that your best plan would be to make a direct appeal to your wife, and to ask her to share her secret with you?"
It's interesting that Cubitt will go behind his wife's back but will not confront her directly about her secrets. He's basically fighting secrets with more secrets, rather than truth, here. Thematically, Cubitt's actions help to show how lying can itself sometimes be a good, or at least effective, tactic.