"If I tell [them] [they] will not believe me. You may remember the old Persian saying, 'There is danger for [they] who taketh the tiger cub, and danger also for whoso snatches a delusion from a [person].' There is as much sense in Hafiz as Horace, and as much knowledge in the world."
Normally as we look at that line from Holmes's earlier, more sexist days, we just see the gender bias. Drop that distracting element out and you see two distinct things: First, that Holmes was a multi-culturalist. And second, that delusional m-f-ers are trouble. And I would even argue that though the original statement singled out a particular gender, the gender not mentioned is even more dangerous when their delusions start getting snatched away.
Sherlockians have long discussed whether Sherlock Holmes made the right call in allowing his client's delusion to persist in "A Case of Identity." It was pretty much the equivalent of letting Sir Henry Baskerville keep thinking his family was cursed by a deadly demonic hound, rather than dog-murder by a greedy cousin. Holmes could have just been lazy or unsure of his own interpersonal skills in just not wanting to deal with the fallout for telling Mary Sutherland the truth.
Holmes's quandry is one of the more relevant points in the Canon when it comes to American government at this point, and probably Britain's too, but I'll let those folks speak for their system. In America, we definitely have a whole lot of people trying to snatch delusion to the fan club of a certain charlatan, and said fan club just isn't having it. And like Holmes's old Persian saying, there are certain dangers to be feared from those who insist a little bit too hard in their delusion.
Sherlockians have always had this fun little game of pretending Sherlock Holmes was a real part of human history, and it always amused me a bit when some overly-literal soul would cry out against it, fearing that the game might actually cause non-Sherlockians to believe that Sherlock Holmes was real. That never came to pass, but with the internet's connection and amplification effects, we've seen a whole lot of other fictions come to be taken as reality, whether it's as far-fetched as space aliens infiltrating society or as mundane as holding that a basic scientific principle is false. Knowing where the actual line between fiction and fact is, well, that always seemed like something Sherlockians were good at, having danced on that line for a hobby. Like any large group of humans, however, some of us are better or worse at that.
But, in the end, we're all in the position of Sherlock Holmes at the end of "A Case of Identity" or The Hound of the Baskervilles. Do we let delusions persist? Or do we at least attempt to point out that maybe things aren't exactly as our countrymen believe them to be on occasion?
One wonders what Holmes would think now.