Some things are, by their nature, very difficult to remember. One might say they have antimemetic properties, sealing themselves off in inaccessible vaults of memory.

I’m thinking about an announcement that plays before every movie shown at my local cineplex. Something along the lines of, Your feature film is about to begin. Please silence your cell phones. A deep voice, friendly but authoritative, booming from the surround-sound speakers and resonating throughout the theatre. I remember in the soundtrack there was a sparkling piano, noodling along in the high registers, free and indeterminate. I liked the sound of it, and can even recall some of the melody as it twinkled and reverberated between the lines.

This is an innocuous memory, but it took me great mental willpower to retrieve. Why is that?

Every time I sit through that message, I think to myself, Gee, I wonder if I can find this on YouTube so I can listen to the piano. I make a mental note to myself. Try to look this up when you get the chance. But I never remember to, because by the time I get the chance, a whole movie’s worth of events has happened, overwriting my short-term memory!

Why not set a reminder for myself on my phone? Because I don’t want to have my phone out during the Please put away your cell phones announcement. That looks bad. And so I have to rely on mental reminders, which, as noted above, don’t work here. And then I’ll probably forget all about it within the first five minutes of the movie.

Can I ask someone else, sitting next to me, to remind me? Perhaps, but it’s a very minor and silly thing to ask, and more importantly they’ll also forget about it within the first five minutes of the movie.

Evidently I managed to catch this memory while it floated across the workspace of my mind; otherwise, this essay would not exist. How did I do that? The memory popped up out of nowhere during a meeting at work. I can’t remember if it sprang from something someone said or if it was entirely unprompted. I recognised it: Oh, it’s that memory! Better trap it while it’s still here or else I won’t think about this for another five years. So I trapped it in my notes and wrote it up to-night, although I haven’t been able to find it on YouTube yet.

But the more general phenomenon of Very-Difficult-To-Remember Things tantalises me so. By definition I don’t know what they are, or how many of them there may be. I only know that I do have some such memories, locked away and unreachable. They’re like dark matter. I can only infer their existence indirectly. Somewhere they slither and frolic far below the surface, prisoners in a shadow world, passing years in the Land of Forgotten Things.