Every once in a while (these once in a whiles often correspond with my birthday--in this case, my 31st), I like to think back and figure out what my earliest memory might be.

As near as I can recall, I've never been able to remember a time before my brother Matthew was born (I was a little more than 21 months old at that time). But I do have a number of vague memories of life in College Park, Maryland, a time which ended a couple months after my third birthday.

Here's the catch. Does remembering that I could remember something (a second-hand memory, perhaps?) count as a memory? For that matter, what exactly is a memory, anyway?

I think I'm moving toward a two-part definition. The first definition covers what might be called a "full" memory. When I think of the occurrence in question, I can often remember the exact date (at least the month) and I am able to fully replicate the emotions of the moment. For example, I can still feel the thrill of hearing an entire camporee of Boy Scouts cheer in full throat when George Brett whacked a home-run off Goose Gossage in the 1980 ALCS. A camporee where the playing of radios after 10 p.m. was strictly verboten, I might add. So a thousand or so boys and adult leaders were breaking the rules, playing the game at a low volume and working very hard not to get busted by the camporee cops, but in one moment of glee we all screamed out our delirious joy at the prospect of the Royals in the World Series, rules be damned.

Definitely a memory.

But what about my recollection of the evening back in the summer of 1972 when my mom was hanging out a couple of houses over? I supposed to be asleep, but I decided that I needed to get up and find my mom. I knew where she was, and so I started a seemingly lengthy trip across two backyards to the ol' klatch. In the backyard between our and the one where my mom sat with her friends lay a kiddie swimming pool. And a dog. The dog rushed me, I got knocked in the pool, I cried, my mom came and picked me up and I spent the next 10 years harboring a deathly fear of dogs, no matter how small.

The thing is, I remember being scared, but I can't actually put myself in the middle of that experience and feel the fear wash over me once again. I can't get inside that moment. It's gone. I know how I felt, but I can't relive the experience.

That's the other kind of memory. The ones I don't trust so much. Because those memories, the ones without a still-palpable residual emotional impact, are mere abstractions of images and thoughts.

A few years back, I insisted that I'd met my wife's maternal grandmother. I could describe her fairly accurately. I even had this scenario in my head as to how the meeting took place. Problem was, we hadn't yet met. Apparently I saw a picture of her somewhere and turned the memory of simply seeing that photo into an actual meeting.

Everybody does that. The problem is, once memories fade into basic abstractions, once the emotional component is wiped away, there's very little you can do to ensure that your mind doesn't drop those remembrances into the wrong folder.

So my earliest memories? I remember College Park. And I can distinguish between my memories of College Park in 1972 and 1973 and those of September 1997, when my wife and I hopped off the Metro (on our way to a World Cup qualifying match with Jamaica) to take a look at the "old neighborhood." But I can still feel my anger at taking a wrong turn in 1997. In fact, I still recall my frustration that day from leaving the tickets at home in York and not realizing that until we'd reached the Baltimore beltway. 1972? Fleeting images. A general feeling of happiness and contentment. That's about it. Not too bad for a geezer who turned 31 today.

Jon Worley spent his 31st birthday sampling various ESBs.