The subject was the artist Cassius Marcellus Coolidge, who made 16 oil paintings of anthropomorphized dogs in the early 190Os for Brown & Bigelow, a Minnesota calendar firm. The paintings are mostly about poker but also depict dogs engaged in other manly pursuits, like playing pool, watching a baseball game, and arguing a breach-of-promise suit. Over the decades the Coolidge paintings were occasionally revived as promotional items, mostly for liquor or tobacco companies, but by the early 1970s they were virtually unknown.

Davidson recalls how she found out about Coolidge: “My mother and I were antiquing, and she spotted two paintings for $300 apiece. That seemed like a lot of money, so it never occurred to me to buy them; instead I sent a photographer and had them shot. I’ve been kicking myself ever since. Of course, the antiques dealer is probably kicking himself even more.” And well he might; in 1998 a Coolidge dog painting sold at auction for $74,000.

The resulting article elicited the greatest outpouring of letters in American Heritage ’s history—even more than we got after putting Jane Fonda on the cover or calling Robert E. Lee overrated. Almost everyone wanted to know where to get copies of the paintings. The art world took notice as well. In the April 1973 issue of Antiques , an advertisement for an estate sale showed one of Coolidge’s paintings with the note “Reproduced ‘American Heritage,’ February 1973.” From the antiques world, the fad diffused to dog lovers, to the general public, to cultural ironists, and back again.

Coolidge’s dogs can now be found on ties, shirts, mousepads, and even wall tapestries made in Lebanon by no doubt puzzled local weavers. His poker scenes have been parodied everywhere from “The Powerpuff Girls” to an ESPN commercial. The phenomenon has spread around the world. A lesson plan for South African students, missing the point somewhat, asks: “The artist Cassius Marcellus Coolidge produced a series of paintings showing dogs playing poker. What do you think he was trying to say? Bear in mind that these pictures were painted in the 1910s, shortly after Queen Victoria’s reign.”

An economics textbook uses a dogsplaying-poker painting to illustrate the concept of elasticity of demand. Weird Al Yankovic, the ultimate arbiter of hipness, mentions Coolidge’s work in his classic song “Velvet Elvis.”

Coolidge’s genius lay in his perfect matching of subjects