In 1930, sitting at his breakfast table in Cedar Rapids, Iowa, Grant Wood sketched his sister, Nan, and his dentist, Byron McKeeby, on the back of an envelope. Practically everyone's familiar with the painting that resulted: the dour man in overalls gripping his three-pronged hay fork, the weak-chinned woman with a cameo and a center-parted bun, and, looming behind them, the white clapboard farmhouse with its famed Gothic window. Now, in time for the painting's 75th anniversary, Steven Biel, head of Harvard University's program in history and literature, tries to bring those iconic sour faces to life. American Gothic: A Life of America's Most Famous Painting (Norton), his slim, breezy study, traces the uses and abuses of the work from its debut at the Art Institute of Chicago through its appearance in countless parodies. Initial reception was mixed: Wood took the bronze at the AIC exhibition he painted it with an eye toward, but the judges' panel was underwhelmed, and it wound up in the museum's collection only at the behest of a trustee. Gertrude Stein was among its early defenders--"We should fear Grant Wood," she announced, "for his devastating satire"--but during the Depression the artist was lambasted by social critics for glossing over the economic hardships and sheer dirt of farm life. Later, middlebrows praised the work for picturing the "stout hearts and firm jaws" of common folk while the champions of modernism castigated its "virulent provincialism." These days, as Biel's book shows, the painting lives on not so much for what it has to say as for what it can be used to sell--everything from cornflakes to Saks Fifth Avenue to the home of the stone lions itself. Thu 7/21, 6 PM, Fullerton Hall, Art Institute, Michigan & Adams, 312-443-3600. Free with $12 suggested museum admission; $7 students, seniors.