Memory is an untrustworthy thing. Large parts of my life are stored in my brain as undifferentiated blocks, marked by images of the place where I lived and faces of my family and friends at the time. I have to be reminded of specific events to recall them, sparked by an old photograph or the retelling of a story. I wonder if the version of the past I hold in my mind is historically accurate, or just an educated guess based on what I must have been doing given a certain age and location.

For about seven years of my life, many of those images involve me sitting on the brown carpeting of my childhood bedroom, hunched over boxes of baseball cards. This period stretched from when I started playing Little League at age nine until I got my driver’s license at 16. Of course, I did other things in this time period. Playing “Lot Ball,” a bastardized version of baseball that was essentially a home run derby with tennis balls in the empty lot across the street from my house; pickup basketball in the driveway; marathon sessions of Mike Tyson’s Punch Out and Zelda on the Nintendo. But if I picture myself alone, it’s almost always involves shuffling and sorting the stacks of cards I kept in white, corrugated cardboard boxes in my bedroom.

This sorting process turned into a kind of Zen ritual that only a kid can surrender himself to, a single-minded immersion that escapes me now as a perpetually distracted adult. I could do this for hours, usually after pedaling my bike to the drugstore to spend my allowance on a new box of unopened wax packs. I liked to assemble complete sets, subject to the luck of the draw, which meant that each new haul required hours of sorting by the sequential number of the back of the cards. I made meticulous lists of the cards I still needed on loose-leaf notebook paper and kept them in three-ring binders.

Despite how much care I put into collating my card collection, it languished in my old bedroom closet at my parents’ house until they retired and sold the house last year. When they moved I hauled them back with me to Chicago, where they landed in my son Carter’s bedroom.

It took me a few weeks after I gave them to Carter to get over my initial instinct of treating each card like a sacred artifact. The very reason they sat in a closet until I was 34 was that I knew they were worthless, ruined by the iron market forces of supply and demand. My collection was compiled from roughly 1986 to 1993, during the era when as many as four major companies were printing millions of cards while every kid and greedy adult, burned by memories of Mickey Mantle rookies mangled in bicycle spikes, preserved each and every card like it was the personal stationery of Abner Doubleday himself.

I finally let go and let Carter do what he wanted with my cards, which at first was a lot of what I expected: flipping through all of the sets and asking a million questions about which player this and what player that. But after this initial discovery phase he started doing something that surprised me (maybe just because I never thought of it as a kid).

One by one, he takes each set, sorts them into teams and lays them out on the floor, arranged like a real field with players in position according to the cards. Then he acts out whole games, picking up the team in the field and laying out the opponent every three outs. I’m not sure of his logic for determining hits and outs; it’s part Strat-o-Matic, part pickup game. He stands by home plate and walks into the field, holding his hand up to track the flight of a batted ball. Somehow to him, it all makes sense.

He keeps scoresheets in his jagged, first-grader handwriting, with batting lineups and tally marks for the score. A few weeks ago, I watched him work on one from a 1986 Topps Traded set. I cringed when I saw him handling the Barry Bonds and Will Clark rookie cards, but I was more interested in seeing his mind work as he jotted the names down on a notepad. On the surface, collecting baseball cards is an extension of fandom, another way to connect with the game, but it’s really about building an interior world, ranking and sorting and organizing players according to the way you see fit.

I meant to ask Carter about what he was doing with the lineup written on that piece of paper, with its somewhat dubious Murderer’s Row of Kurt Stillwell, Will Clark and Billy Sample, but he was acting up that night and we put him to bed early. Maybe it’s better that I don’t know. I’m starting to see flashes of a sulky teenager in him already, and if he’s anything like me he’ll soon be spending more and more time in his own private world. Maybe he wouldn’t want to tell me anyway.

Parenting is a constant exercise in finding connections to your own past through your kids. “This thing I created must be like me!” I keep trying to find those links in the baseball cards. Maybe Carter is into them because they were mine. Maybe there is no other explanation than that he’s a seven-year-old kid who likes baseball.

When I see him sorting those cards, or when I shuffle through them myself, I sometimes feel a tightness in my chest and the beginnings of tears welling up behind my eyes. I don’t know where it comes from; it’s not like my baseball cards represent anything unhappy in my life. I collected them in a world where I was most content, crouched by myself and mostly inside my own mind, the place where I’m most comfortable today.

The school year ended last week for Carter and my three-year-old daughter, Sadie. With that came home two backpacks full of the crayon drawings, photocopied sheets of math problems and notebooks full of mostly illegible but promising-looking handwriting. As I sorted the detritus of a completed year of first grade and preschool, that same feeling I get from looking at my baseball cards caught in the back of my throat, welling up in my sinuses and making me take a few startled, deep breaths. It’s not unhappiness, I realize, but the familiar, suffocating sentimentality that sneaks up on me sometimes. My children have graduated from another stage in their lives, each a step closer to the day they’ll no longer need my help.

I continued to empty out the backpacks, sorting the junk from the particularly funny drawings and assignments that I’ll save in two file folders with their name and school year written on the front. I’ll stack these folders high in their closets, where they’ll stay until they move out for good. Maybe they’ll decide to take it all with them; maybe they’ll say they don’t want it. Either way, I probably won’t have the courage to sort through it again. Those folders will stay perched in their closets like my baseball cards occupied a corner of my old bedroom, boxes of colorful memories from happy times that somehow make me incredibly sad as they recede into the distance.