Why do we remember what we remember?

Memory works in strange, discomforting ways. When I was younger, I remembered everything, or at least everything that vaguely interested me. Last week, for instance, when challenged unexpectedly, I rattled off every Grand National winner from 1980 to 1994. I have absolutely no idea if I ever deliberately learned them off by heart or why the run should stop in the year I finished school (does booze really damage you that badly?), but they're there, seemingly indelible, in a place that could much more usefully be occupied by, say, the birthdays of friends and family.

I used to remember the details of every football match I'd ever been to and get annoyed with my dad because he couldn't. I assumed memory was cumulative, maybe not for remembering to turn on the washing machine for my mam, but certainly for remembering Sunderland goalscorers. Now, though, I've become one of the old gits in the press room whose response to pretty much any question about a game last season is to stare into the middle distance and ask, "Was I there?" before going through old files on the laptop to check.

For a time I had a theory that forgetfulness was a useful filter: your brain just got rid of what wasn't relevant, that process of natural wastage went on and was generally useful. Nobody, after all, wants to end up like Funes the Memorious, the character in the Borges short story who could remember everything, taking 24 hours to reconstruct in precise detail the memory of a day; dealing only in details, he was incapable of generalities, and thus, Borges suggested, of deduction or induction.

But the older I've got, and having seen my father destroyed by Alzheimer's, the more I've realised that memory is a precious, tenuous thing, that forgetfulness is not rational, but eats everything in its way. Yes, the trivial may be consumed rather more quickly, but significant memories go too in the case of Alzheimer's, in the most painful, humiliating and terrifying ways. Of course, given the option, I'd delete the 16 lines I learned for the part of Ligarius in a school production of Julius Caesar ("Vouchsafe good morrow, from a feeble tongue I am not sick if Brutus have in hand/ Any exploit worthy the name of honour") and replace them with, well, with almost anything, but for the sake of finishing the paragraph, let's say a clear recollection of the view from the top of Kilimanjaro.

Perhaps it is all random, but the tendency is to ascribe significance to those memories that remain. Why that one? Why that moment in particular? Last weekend, on my way up to the Stadium of Light for Sunderland's game against Chelsea, I went along Newcastle Road. Where the swimming pool used to stand, houses are now being built. "Your dad would be heartbroken," my mam said.

Frankly, I doubted that: he was never sentimental and I'm pretty sure that he would quite happily have driven the extra few hundred yards to the National Aquatic Centre that replaced it. But still, it was somewhere he had gone to roughly once a week for the last half of his life. I was struck, suddenly, by a profound memory, one that was unnerving in its vividness.

When I was a kid, my dad had taken me to the baths every Saturday morning. I'm not sure I'd particularly enjoyed it: I've never enjoyed getting wet, and my vague sense of the place is of cold floors and disconcerting echoes, but it was the thing we did. One day, on a bright, sunny morning, we walked back across the car park. My dad was driving a gold Austin Maestro. My dad dropped the bag in the boot, got in, reached across and opened the back door for me, then turned on the radio. That moment, there, is crystal clear: the smell of chlorine off my hair, pulling on the seat belt, the bright sunlight, the fluttering of a white plastic bag caught in a tree, and the - as far as I was concerned - unprecedented news that England were more than 200 without loss. Then the memory fades, leaving behind only the vague feeling that disappointment followed, that wickets fell and that England didn't rack up the monstrous score that had seemed possible.

Of course, the beauty of modern technology is that it takes a matter of seconds to isolate exactly when that happened. It was July 16, 1983. I'd just turned seven and it was the third day of the first Test between England and New Zealand at The Oval. England, having won the toss, were bowled out for 209, then dismissed New Zealand for 196 (a score they reached thanks largely to Richard Hadlee's 84 off 78 balls).

By the end of the second day, Graeme Fowler and Chris Tavaré had got England to 146 for 0 and, 60 or so runs later I got into the car in the swimming pools car park on the Saturday morning. Fowler got 105 and Tavaré 109, out with the total on 223 and 225 respectively, before an unbeaten ton from Allan Lamb got England to 446 for 6, at which they declared and bowled New Zealand out to win by 189 runs. England went on to win the series 3-1.

Looking back over the scorecards, a handful of things stand out. First of all, there were only four Tests, which, even with England hosting the World Cup, seems unthinkable. Secondly, England batsmen kept making centuries and not kicking on: six of the seven tons by England players in that series were terminated between 102 and 112, either by being out, declaration or running out of partners. And thirdly, England seemed pretty confused as to who their best spinner was.

But I'm more interested in the implication of my surprise at England being 200 for 0: that means I hadn't known what the score was on the Friday night. What was I doing then that I'd missed that? Or is that just the way kids consume sport: they watch it without really understanding context.

And why, most importantly, is the memory of that Saturday morning so vivid? It feels like what Joyce would call an epiphany or Wordsworth a spot of time, a moment that takes on an enhanced importance, that somehow brings us to radical insight or, as Wordsworth had it in The Prelude, "lifts us up when fallen".

But why? Why that in particular? I didn't even like swimming. But perhaps that's the point. Happiness is rarely self-aware: perhaps that was the essence of my relationship with my dad, mutual weariness after physical exercise and sitting in silent communion listening to or watching sport.