WERE it not for Filene’s Basement, I would have gone to my proms in a potato sack.

It was there, at the flagship of the now-defunct discount retailer, on Washington Street in Boston, that I scored my Madame X gown: black velvet with the one (rhinestone) shoulder strap, marked down to $19 and not only gorgeous, but from I. Magnin. That was a magical name, light-years removed from the Basement chain, which recently closed, sunk into bankruptcy.

My mother saw the dress first. She grabbed for it, microseconds ahead of another shopper (you had to move fast in Filene’s Basement), and I tried it on, right there on the floor.

Dressing rooms? Don’t be silly. You pulled it on over your clothes and elbowed your way to a sliver of mirror, just like everyone else. And if other women eyed you and hung around, jockeying for position just in case you weren’t buying it — that was when you knew you had a winner.

I wore that gown to my junior prom and my senior prom and a couple of Harvard proms. That rhinestone strap was mangled in the back seats of cars and mended each time to twinkle yet again, and when I graduated and came to New York to find a job, the Madame X came with me.