Before he retired, my dad sold things for a living. Anything from newspapers to antiques to hardware. He wasn’t the kind of salesman you might imagine today, though, smartphone in hand, rushing to the next opportunity. He was the old-school kind, the kind who shared a joke and a story at every call and who, through the vehicle of his words, formed friendships that lasted a lifetime.

My fondest memories of my dad are of him holding court among laughing friends or sitting intimately with our family at the dining room table, telling stories. It’s the stories I remember most, particularly the warmth and generosity with which he shared them.

Many of my favorites revolved around the mischief my dad stirred up as a boy in a small southern town. Like the night he switched all of the neighbors’ patio furniture. Or the times he and his friends would loosen the tops of saltshakers or wet the tips of paper straw wrappers to create a sea of stalactites on the ceiling of the local diner.

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But the story I think of most often, the one that has had the most impact and never ventures too far from my heart, took place on a sweltering day in 1947, as my dad sat waiting next to his father, my Grandpa Sydney, at a dusty bus stop outside Columbia, South Carolina.

It’s a story my dad has retold many times, often at my request, and one I imagine crackling in black and white like an old home movie.

Grandpa Sydney is seated on a wooden bench. A fedora rests atop his slicked-back hair as sweat slowly dampens his dark wool suit. My dad, seated next to him, is a seven-year-old boy sporting a flattop haircut, a plain white tee shirt, and blue jeans rolled at the ankles.

Grandpa Sydney, smelling of coffee and aftershave, peruses the sports section as the occasional car rumbles by. My dad, looking for trouble as usual, surveys the surrounding area and finds one of those old-fashioned vending machines that for a nickel, drops down a paper cup, then automatically fills it with ice and cola.

A bright idea flashes across my dad’s mind. He reaches up into the dispenser’s narrow opening and crushes the paper cup within to give the next customer a messy surprise.

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Just as he is about to rejoin his father on the bench;, having gotten away with his prank, Grandpa Sydney coolly folds his newspaper and strolls over to the soda machine. My dad’s heart pounds as his father steps closer and closer to the machine.

Photo: Jim Petkiewicz/Unsplash

Grandpa Sidney drops his nickel into the slot. He watches the crushed cup descend into place, then stands perfectly still as the ice and cold soda cascade over the crumpled paper, splattering down all over his pant legs and shoe tops.

Just then, the bus arrives. Grandpa Sydney gently grasps my dad’s hand, climbs the stairs, takes his seat, and, for the entire trip, doesn’t utter a single word.

My dad still doesn’t know if Grandpa Sydney knew he had crushed the cup. The incident was never mentioned, and what happened that day remains a mystery.

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When my dad tells the story, there is always a hint of moisture in his eyes. Did Grandpa Sydney happen to get thirsty at that moment? Was the timing of his trip to the vending machine purely coincidental? Or did he decide the lesson needed for my dad at that moment was best taught in silence?

My dad never asked the question, and Grandpa Sydney passed away before I ever had a chance to meet him and ask him myself. Looking back over the years, it’s amazing how many times I’ve pondered the meaning of this story.

When I share this with my dad one morning, he smiles and says, “Me too, Daniel. All I can tell you is that since then, I’ve tried my best not to crush other people’s cups.”

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Dr. Daniel H. Shapiro is a writer, keynote speaker, and contributor to YourTango. He’s had articles featured in Medium and is the author of The 5 Practices of the Caring Mentor: Strengthening the Mentoring Relationship from the Inside Out.

This article was originally published at Medium. Reprinted with permission from the author.