No matter how good my memory is, I forget things.
The things I forget tend to fit into two categories: that which I need an artifact to recall, and that which sounds foreign, even when I see evidence of it.
Dresden Codak addressed one face of this in a poignant comic, about future memories. The upshot of it, though, is that I think I have a good memory mostly because I've forgotten things I forgot… my bias is showing.
Some things I recall better than others, but perhaps because I obsess over them—reading and re-reading stuff from my Facebook timeline or what have you—but there's clear evidence that without pictures, documents, objects, souvenirs, and so forth, my brain prunes out or otherwise makes inaccessible whole portions of my life.
For instance: I can recall, broadly, what I was doing in 2011 only by remembering where I lived at that time, and then thinking of the sorts of things I did in that place. But otherwise the entire year is blur.
I don't think this problem is going to get less acute over time. Journaling is a way, then, to mitigate some of these effects.
Bruno laughed around the stem of his pipe. “Yes, make it work. Clever lad. Alas, I fear I'm not up to the task. These old chalkboards are getting white.”
“Chalkboards. Blackboards. Ah, what do you children know?” The cloud around him thickened with his huffing, and he waved it away. “In the tradition-heavy wilds of Catalonia, where I cut my first set of teeth, the last vestiges of the stone age lingered very nearly until the rise of the Queendom. A chalkboard was a slab of hard, dark slate onto which you would scribble with little cylinders of soft, white chalk. Really! We had one in every classroom, every kitchen. You'd erase the board with a rag, you see, and write in a new batch of lessons or chores or ingredients. But sometimes you'd misplace the rag, and you'd have to scribble around the margins of what you'd already written. If you let this go on long enough, eventually the board would get so white with scribbles that you couldn't read it anymore. And so we learned: too much knowledge is as bad as none at all. We forget how to forget."
–Wil McCarthy, To Crush the Moon