I recently discovered a wonderful book by Maria Konnikova called Mastermind: How to Think Like Sherlock Holmes.

It’s basically a review of the Baker Street detective’s remarkable brain powers based on contemporary cognitive science.

Among other excellent observations, Konnikova makes this point about the close relationship between memory and working knowledge:

We know only what we can remember at any given point … No amount of knowledge will save us if we can’t recall it at the moment we need it.

Since knowledge and memory are so intimately intertwined, it’s crucial that we properly stock and maintain our memories–which Konnikova, following Sherlock Holmes, calls our “brain attics.”

Like actual attics, our brain attics contain limited storage space. In order to use that space effectively, we need to store what really matters and discard what really doesn’t. And in order to tell the difference, we need to notice the connections between potentially consequential clues even as we disregard a wide range of other, superfluous, details. We need to maintain our mental files like genuinely Holmesian sleuths–continually focusing on what’s really important to the case at hand. Simply put: we need to be mindful about our memories.

In practice, of course, most of us rarely pay attention to what we let into our minds. Most of the time, we simply allow the world to wash over us–and other people’s ideas to wash into us–without ever consciously asking ourselves “what of this do I need to remember?”, much less “what of this should I try to forget?”

We rarely take the time to think back on the day (the week, the month, the year) to identify what it taught us, to record the consequential clues it contained and update our mental files. Instead, we just keep rushing forward, pouring more and more information into our brains and hoping the right connections will somehow, miraculously, form themselves.

As Sherlock explains to Watson in A Study in Scarlet, this is foolish:

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 out … [By contrast] the skillful workman is very careful indeed as to what he takes into his brain attic.

Since Sir Arthur Conan Doyle wrote those words 130 years ago, the availability of information has skyrocketed. Today, we not only have our brain attics; we have Google, and Siri, and the worldwide web in the palms of our hands.

But with all of those facts at our fingertips, our minds are no better ordered. Unless we stop and pay attention–unless we take the time to look closely and listen carefully for what’s important–we’re bound to just keep cramming our brains with clutter.

If we want our minds to work better, we have to take the time to dig through our memories, to discover the hidden gems and ditch the garbage, to forge the connections that ultimately make our stories come together. At the end of the day (the week, the month, the year), we have to remember to ask ourselves “What mattered? Why? And how am I going to keep it?” Otherwise our minds are likely to feel a bit overburdened, and our lives are likely to remain a bit too mysterious.