John W. McCoy is not a name art critics and museum-goers readily know. If it were not for a comprehensive exhibition of his works now at the Farnsworth Art Museum through Oct. 14 in Rockland and then in November at the Biggs Museum of American Art in Dover, Del., it is likely that McCoy’s paintings, as well as his bolstering contribution to art history, might be lost to all but a few friends, family members and insiders.

Pinpointing McCoy’s style is not as easy as saying he belonged to the American realist school. His early paintings – of models, of Maine seascapes, of the landscape in Chadds Ford, Pa., where he apprenticed under the artist and illustrator N.C. Wyeth – are immensely skillful both in the control of the brush and in the fidelity with which McCoy had taken a clear-eyed hint from other American landscape and seascape painters. In work from the 1930s and 1940s, you can see him conversing via watercolors with Winslow Homer, or in oils with Cezanne, or tempera portraits of architecture with Edward Hopper. But McCoy’s talent never headed in the direction of gimmickry.

Later in life, McCoy, who was born in 1910 and painted until 1989 when he died of Alzheimer’s, developed a mixed media technique by combining watercolor, oil, acrylic and pastels. He called the style “McCoy’s mixed media” and, while it resulted in the most stunning pieces of his oeuvre – see “Sailboats,” “Four Gulls,” “Moonflowers” and “Bell Buoy off Tenants Harbor” – it also was, in more daring moments, indebted to Jackson Pollock and other artists who were breaking out of the limitations imposed by art schools. McCoy did not so much engage in that wave of innovation as uphold the practices of American realism while the art world blazed around him.

In the end, the real influence on McCoy – as a painter and as a person – was his close association with the Wyeth family of artists. While he was studying in Chadds Ford, McCoy met and eventually married Ann Wyeth, daughter of N.C., sister to Andrew. His place among the Wyeths, an intensely enveloping and rambunctious family, became lifelong, and the artistic proximity can be seen, depending on your perspective, as either helpful or hurtful to McCoy as a painter.

According to the Wyeth family, N.C. brought McCoy into the studio to be “competition” for the younger Andrew, who was studying to become a serious artist under the disciplined tutelage of his father. McCoy, who had grown up in New Jersey and Delaware, had been an art student at Cornell University and in France, and was studying at the Pennsylvania Academy of the Fine Arts in Philadelphia at the time. He had dreams of designing theater sets. But McCoy, who dropped everything to paint with the Wyeths, must have seen the invitation to apprentice at the Chadds Ford studio as an opportunity that carried a promise beyond his dreams, especially since he wanted to establish himself quite apart from both his family and his family’s background in business.

In “Andrew Wyeth: A Secret Life,” biographer Richard Meryman writes: “Often the two students painted the same subjects – still lifes and local models. When N.C. gave his critiques, he would say, ‘John, you win today,’ or ‘Andy, beat you today.’ ”

After seeing the exhibition, my own feelings about McCoy remain ambiguous. I was moved by the grace of his brushstroke and the meticulousness of his eye, but the narrative that quietly roils beneath the surface of the paintings – about a quiet painter who worked for years alongside a famous painter – became the focus of my interest in McCoy.

In a new handsomely produced art book “John W. McCoy, American Painter,” published by Down East Books to accompany the Farnsworth show, McCoy’s daughter Anna B. McCoy, as well as Andrew Wyeth and Farnsworth director Christopher Crosman, offer insights into McCoy’s work and his quietly diligent place in art history.

“For understandable reasons, McCoy’s work was often compared to Wyeth’s,” writes Crosman. “Yet he was a different painter with unique qualities. … McCoy was also, by all accounts, a deeply private man and artist. His works have a reticence and wonderful serenity, but beneath their placid surfaces there is emotional depth and precision.”

Seen in this light, McCoy appears as a painter whose talent hung in the shadows of Wyeth’s success. If his work was never fully expressed or applauded, it is no wonder. Few artists today have the bigness of Andrew Wyeth.

“I have to hand it to my husband,” Ann Wyeth McCoy said to me in a recent phone conversation. “He handled all that beautifully. He was devoted to my brother. It was a tough position to be in, and he never had a chance. Finally with this show my husband may be getting an in.”

When I commented to Crosman recently that the show, which is entirely accessible and indeed lovely, might not be the best example of cutting edge programming at one of the major museums in New England, he cautioned against thinking narrowly.

“Except for a few biased critics in the art world, most people are taking a look at painters who were written off years ago,” said Crosman. “It’s a much more radical approach to say the lesser known artists might have some merit. McCoy is an under-seen artist. He was there at the beginning of the Farnsworth and, on the behalf of other artists rather than his own work, helped shape the collection.”

The show, with its repressed rumblings of an artist struggling to find his own voice, may ultimately be a daring presentation for the Farnsworth. If that’s true, then it is at least as much about McCoy’s life as it is about his art.

One of the museum staff members strolling about the galleries on the day I visited asked if I had seen the McCoy show and if I liked it. I said I did but that I was not sure McCoy was a great artist. We had a discussion about “greatness” and “success” in art. And finally, the worker, who is also a painter, said the relationship between Andrew Wyeth and John McCoy had been better for Wyeth than for McCoy, that McCoy was a skilled artist whose work was simply used by a zealous father to propel the career of his favored son.

“It’s like the parasite and the host,” this person whispered to me. “That’s just the way life is sometimes.”

Surely that is too harsh a judgment on the Wyeth clan. And we would have to know the inner life of McCoy to defend or maintain such a position – and even Ann McCoy says that, after all these years, even she wonders if she knew her husband well. Nevertheless, one cannot help being provoked by McCoy’s story and the what-ifs that surround it. The complexities of his life remain elusive in both the new book and the show. And perhaps that is simply the luck of the draw. How many artists’ lives are untold?

Crosman, however, rightly upholds a mission to explore American art and present shows that are engaging in ways that go beyond a single painting, a man’s commercial success, or the needs of a museum.

“It’s important from time to time to take a hard look at artists that have not been trendy or have been left in the dirt of art history,” Crosman told me. “When it comes down to it, it’s about what interests you personally. I’m personally interested in McCoy and have begun to realize he is a very, very good painter. He won’t ever be world famous. But John McCoy was a gifted artist.”