The theme of this remarkable biography of America’s most famous painting is the dramatic shifts in perception over time of both its artistic worth and cultural significance. As the author repeatedly demonstrates, Grant Wood’s iconic portrait of a grim Iowan with a pitchfork and his tight-lipped consort has been a virtual Rorschach test for critics and the general public. What people found in the painting was often an accurate reflection of their own transient interests and concerns.

This is an original book and a profound one. Although written for a general audience, it raises provocative questions about objective values and meaning in art. It explores the severe disconnect between high- and middlebrow culture that characterized the middle part of the last century and the subsequent flight from established standards and canons – a departure that promoted irony, camp sensibility, and the elevation and exploitation of pop culture.

That is considerable ground to cover in fewer than 200 pages, but Mr. Biel, director of the history and literature program at Harvard University, has done it without losing his focus on the unique piece of work that is Grant Wood’s “American Gothic.”

“The story begins with Mencken,” Wood once told an interviewer. Certainly the initial reaction to the painting, when it was acquired by the Art Institute of Chicago in 1930, reflected H.L. Mencken’s influence. A gifted cultural polemicist who coined the term “Bible Belt,” Mencken was a relentless critic of Puritanism and Philistinism as the twin blights on American civilization. He would have despised the two “rubes” in Wood’s painting, and most people agreed that it was indeed a satire and attack on the homely Midwest virtues Mencken lampooned so effectively.

In fact, not a few of Wood’s Iowa neighbors took offense at what they clearly regarded as an assault. One farm wife reportedly told him he should have his “head bashed in.” Another described the man in the painting as “the missing link.” Wood, a dedicated Bohemian in his early student days in Paris, apparently made the prudential decision to obfuscate. “I do not claim the two people are farmers,” he told the press. “I hate to be misunderstood, as I am a loyal Iowan and love my native state. All that I attempted to do was to paint a picture of a Gothic house and to depict the kind of people I fancied should live in that house.”

As the Great Depression gripped the nation, and as the initial controversy flagged, Wood’s salt of the earth interpretation gathered strength. “American Gothic” became the indomitable American spirit, plain-talking and grittily determined. Eleanor Roosevelt even paid a visit when the painting became a centerpiece of the Century of Progress World’s Fair in Chicago in 1933. This heroic view related the painting to John Steinbeck’s Joad family in “The Grapes of Wrath.”

But it didn’t wash with all the critics, particularly on the left. They wondered why the house and barn of the painting were in such good repair when banks were foreclosing on property all over America. At New York City’s Town Hall, a gathering of artists sponsored by the American Communist Party heard the head of the Iowa gallery that first showed Wood’s work distance himself from the native son. Wood was “popular because he was reassuring,” the director sniffed.

Despite the misgivings of some, the American public embraced “American Gothic” to an unprecedented degree. Newspapers, with newly acquired rotogravure capability, featured the painting on their front pages. Reproductions repeatedly sold out. The Art Institute, with a growing collection of masterpieces from the School of Paris, reported more public interest in Wood than in Monet or Renoir.

When war came, the heroic character of the picture changed further, as the pictorial equivalent of “don’t tread on me.” Henry Luce’s Fortune Magazine even proposed a war poster featuring the painting underlined with Lincoln’s vow, “Government of the people, by the people and for the people shall not perish from the earth.” One Albert O. Olson, of Glencoe, Ill., printed a pamphlet, “Stopping at Grant Wood’s ‘American Gothic'” that stated in part, “The Germans may today slay a thousand Danes or two thousand Norwegians, but the man with the pitch fork knows that clover will blossom again and that he will have hay to pitch when the cows come home.”

By this time the painting was so well established in the imagination of the people that it was uniquely positioned for the many parodies and takeoffs that accumulated from the end of the war until the present day. As Mr. Biel notes, starting in the 1960s, with Lyndon and Lady Bird Johnson, every couple that has occupied the White House has been plugged into the image at one time or another. Popular television shows, from the “Beverly Hillbillies” to “Green Acres” to Paris Hilton’s “The Simple Life,” have made use of the image. Acid political cartoons, beer advertisements, Ken and Barbie dolls, and Mad magazine are all a part of the ever-expanding “Gothicana.”

An interesting sidelight in the book concerns the aesthetic issues associated with the painting and its public reception. Clement Greenberg, who helped establish the Abstract Expressionists as the dominant postwar force in the American art world, disdained the painting as kitsch. When several of Wood’s supportive critics mounted a retrospective of his work in the 1980s, the venerable Hilton Kramer blasted the exhibit as an example of camp and blamed Susan Sontag’s “Notes on Camp” for the decline of standards that would permit Grant Wood a respectful retrospective. Others, including Robert Hughes, were friendlier.

Mr. Biel presents these and other views with respect and apparent neutrality. He is more concerned with the extraordinary persistence and resonance of the image itself, which is easily as recognizable as the “Mona Lisa” or van Gogh’s self-portrait.

As for the painter, he died of pancreatic cancer in February 1942. By most accounts, he was an unhappy man, with financial troubles, an unraveling marriage, and conflicts with his teaching colleagues. He probably couldn’t have foreseen the commercial exploitation of his painting. But he had already begun to sense its enduring power to fascinate.

Mr. Willcox last wrote for these pages on Richard Haass.