A friend once made the point that a tomato can't be an heirloom unless it was passed down to you from your great-grandmother.
But that is exactly it.
The strange looking tomatoes that we find at farmers' markets and on our plates at fancy restaurants — almost black or green with stripes or bright orange — come to us from the time of buggy whips and bustles.
They were lost to us for years because of our appetite for all things tomato and the need to grow them free of diseases and with the fortitude to travel great distances.
But heirloom tomatoes have returned, almost from the attic, thanks to the generosity of small farmers and ardent seed savers.
"Edible Memory: The Lure of Heirloom Tomatoes & Other Forgotten Foods," by Jennifer Jordan is the perfect summer read. She writes deliciously about the fruits and vegetables that make this time of year such an orgy of freshness. The time when it feels like we are eating sunshine.
She describes heirloom tomatoes as more than packaging for the flavor that has been hybridized out of the ones that travel to us from California in giant refrigerated trucks. They, like so many foods, are also where memories — family memories — reside.
"Once upon a time what we call heirloom tomatoes were simply tomatoes," she writes. Thanks to those who preserved the seeds from our grandparents' time, any of us can grow heirlooms in our little garden plots. Catalogs and garden centers are filled with seeds and plants.
But there is an unpleasant side to heirloom tomatoes, too. They have become a status symbol, a sign of wealth. The farmers that grow them could never afford to eat in the restaurants that tout them on their menus. Heirloom tomatoes are another sign of the income gap.
Instead of simply a way to carry on a family tradition, they have come to signal refinement. They are elitist.
Heirlooms "went from being a private food, grown in the family garden and eaten at home, to a public food, bought by affluent consumers in restaurants, at farmers markets and high-end grocery stores," writes Ms. Jordan.
She describes tasting them in a New York restaurant and finding them "underwhelming." The result, she says, of "the hollowing out of the heirloom label into a fad."
A sociology professor at the University of Wisconsin-Milwaukee, Ms. Jordan is at her best when she is describing the evolving role of tomatoes in our lives and our family histories and in our social currency.
Somewhat less satisfying is her description of the history of the tomato, from its medicinal roots in South and Central America to its journey to Europe and its triumphant return to the New World with Italian immigrants. That section reads like Wikipedia.
But she makes the case that hybridizing — which created the uniform reddish ball that is uniformly tasteless — was not an evil. It was a way for farmers to survive the devastation of disease or drought and to increase the yield to satisfy our demand.
But the industrialization of tomato growing, as well as our insistence that they be available out of season, also decreased the number of varieties. There is no way of knowing what biodiversity was lost forever.
And Ms. Jordan records another fact that I might dispute. She reports that in 2011, the last year for which she had numbers, the average person consumed more than 85 pounds of tomatoes in a year.
I don't know about you, but I might hit that mark in July and August alone.
Susan Reimer's final column for The Sun will appear Sunday. In the future, she can be reached on Facebook and Twitter.