"They can go everywhere, see everything, overhear ever one."
"He sits motionless, like a spider in the center of the web, but that web has a thousand radiations."
"All other men are specialists, but his specialism is omniscience."
If there's one theme that runs throughout the Sherlock Holmes Canon, it is this: Gather as much information as you can.
We know, of course, that Sherlock Holmes advised against trying to keep all of that information in one's head: "I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded our, or at best is jumbled up with a lot of other things so that he has a difficulty laying his hands upon it."
And yet he read all the newspapers he could, gathered every fact on every case, and listened carefully to every client. "Mr. Mac, the most practical thing that you ever did in your life would be to shut yourself up for three months and read twelve hours a day at the annals of crime." Even as he makes his point with Watson by saying he'll forget Copernican theory to make room for something more practical in his head, he's still preaching pouring more data into one's brain.
In Victorian times, Sherlock, Mycroft, Inspector MacDonald, Professor Moriarty . . . everyone had to work at gathering that data. It could only come in so fast, even with all of London's morning papers, criminal networks, and street urchin legions. We're faced with a slightly different situation these days.
Our own legions of Baker Street Irregulars are as vast and undisciplined as can be -- how many different people do you find "reporting" to you every day on social media? Even if you limit your associates on the web, friends of friends of friends have a way of sneaking in. News aggregators pull stories from far more sources than London had papers in Holmes's time. You can search and scroll and jump from hyperlink to hyperlink while YouTube keeps feeding you videos and a podcast plays in the background. How many of us have adapted to taking in multiple channels of input at the same time? If we ever figure out a language that works with smell or taste, we'll probably try to add a couple more.
We're in an entirely different position than Sherlock Holmes these days . . . or are we?
Going back to that "brain attic" speech, and others like it, you can see that Sherlock Holmes was also about how one processes all that input. Even at his start, as he scanned so many disciplines to pull from each the techniques that would be useful to him in his work, you can see him keeping this and tossing that, keeping focused on his goal of improving the art of detection.
I saw a headline recently that claimed human brains were reaching the limit of their ability to take in information. I suspect that Sherlock Holmes, John H. Watson, and every attention-paying Sherlockian that came after have always known there were limits. Everything has its limits. It's what you keep and what you throw away that is the grand trick, and we see a lot of folks choosing to keep the entirely wrong tools in their mental toolbox of late, substituting fantasies for facts. But Sherlock Holmes is still with us, for as fantastic as he was, there are still a lot of useful truths in his example.