The Rev. Loren Abney's sermon at the United Methodist Church in the little farming town of Nokomis, III., is on the spirit of giving. His prime example is Tillie Kottwitz, sitting in the third pew wearing a royal blue dress, a lacy white sweater and a pink carnation. When the Rev. Abney is done, Tillie, whose arthritis has been bothering her lately, rises, and her boys, Merle, 63, and Wayne, 62, each take an arm and help her down the aisle to the organ, where she will present her latest gift. Tillie slips off her left shoe ("to feel the pedals better," she tells anyone who asks) and plunges into How Great Thou Art, her favorite hymn. After that she plays Oh Christmas Tree and concludes with Dwelling in Beulah Land. When she is finished, the congregation stands and claps vigorously.

Matilda Kottwitz, 85, has been playing at church services, weddings and funerals in this town of 2,500 people since 1917. She hasn't been a member of the Ladies Aid Society quite that long—only 55 years—but this particular Sunday marks her 70th anniversary on the church organ. That amounts to more than 3,000 Sundays. "Church and music and my family, that's what keeps me young," she says. "These fingers belong to God," she adds, holding her hand up to the sunlight.

Tillie got her first piano when she was 8. That's when her father, Henry, a German immigrant farmer, took a Voight upright in trade for a plow horse—"a big, beautiful horse, sleek and round," she recalls. For a time she took lessons, but she had to help around the farm, and at 12 she gave them up. "It was too far to walk to classes and the horses were in the field," she explains. After that, she taught herself. "I'd rush through a meal just to get to the piano," she says. "My mother never had to tell me to practice." Soon she was playing preludes at services, and for a while she played at two churches each Sunday—one with services in German. She has never stopped playing, and until the arthritis flared up this fall, she never missed a service because of illness.

In 1923, Tillie married Guido Kottwitz. Merle was born a year later, and Wayne the year after that. Neither has a musical bent, but Tillie's gift has been passed down to Larry Kenton, one of her 10 grandchildren, who is a professional singer and arranger in California. Sometimes the two play Mister Sandman as a duet. At home, she likes to play Mister Sandman, America the Beautiful and Flitting Little Firefly, one of her own compositions. "If I'm tired and down in the dumps, all I need to do is go to the piano or organ," says Tillie, a widow for 31 years. "It just changes everything."

Despite the arthritis, Tillie still gets around, driving to Ladies Aid meetings in her 1968 Pontiac and playing Scrabble with Celia O'Malley, who is 89. "I do the driving," says Tillie, "because Cella's up in years." Nokomis has changed since she was a girl—for one thing, the two coal mines in town have shut down—but some things are constant. Tillie Kottwitz is still there, playing the organ and taking nothing for granted. "I still get stage fright," she admits sheepishly. Chances are she'll never get over it.