In 1910, when doctors in her home town of Buffalo discovered that 3-month-old Yvonne Greatwood had polio, they were not sure she would ever lead a normal life.

But for Greatwood, now 74 and living in McLean, there was never any doubt. "I always knew I would beat this thing," she says.

Greatwood's struggle with the disease that terrorized America in the first half of this century is the subject of the autobiography she is writing, "The Other Miracle." It is the story of a young woman's heroic efforts to become a teacher at a time when, she says, "if you were a polio victim, you couldn't get a job, no matter how qualified you were." Greatwood's writing efforts have earned her a grant from Harvard University, where she has taken summer school courses for six years.

Polio, or poliomyelitis, is an infectious disease of the gray matter of the spinal cord caused by a virus that can damage or destroy the nerves that control muscles, resulting in weakness or total paralysis, according to Richard Leavitt of the March of Dimes Foundation.

Dr. Benjamin Nkowane, medical epidemiologist for the Center for Disease Control, says there are no accurate statistics on the number of polio cases in the U.S. before 1932, although there were numerous epidemics before that time. From 1932 to 1949, there were about 6,000 cases annually, but during an epidemic that lasted from 1949 to 1955, the average number of cases jumped to almost 40,000 cases annually, reaching a peak of 57,000 cases in 1952.

By 1957, the widespread use of the Salk vaccine brought the number of cases down to 5,000. An oral vaccine invented by Dr. Albert Sabin is now in use.

Because it was not known for years how the disease was transmitted, victims of polio were frequently shunned by society.

The obstacles Greatwood faced were formidable. Unable to use her left foot as a baby, she was forced to drag it when crawling. At 18 months, doctors put a wire brace on her leg, which enabled her to walk with, as she puts it, "a peg leg."

Dangerously underweight at age 8, Greatwood went to the McLain Sanitarium in St. Louis, where she went through a rigorous exercise routine using weighted machines and even slept with a brace on her leg. The routine strengthened her leg considerably, and, in 4 1/2 months, she was able to walk unassisted.

But polio, she notes, "is a disease that meets you at every age," and with the onset of puberty, the muscle on the top of her left foot suddenly dropped, and she could no longer control her foot. An operation at age 15 enabled her to walk again, but put her back in a brace.

At 19, doctors confined her to a hospital bed for six months, not realizing that prolonged rest would only cause her muscles to atrophy. Greatwood then "tried everything to rebuild that strength," and three years later, in 1932, she entered Canisius College in Buffalo.

After graduating in 1937, she earned a master's degree in English from Canisius, and in 1948, began teaching English full time at McKinley Vocational School in Buffalo.

Teaching became Greatwood's life for more than 25 years, including two years, 1956 to 1958, at Washington's National Cathedral School. Although she retired in 1979, she still considers herself to be, first and last, a teacher. "That's the 'other miracle,' " she says. "The first is that I'm alive, that I can walk, that I can function . The other miracle is that I was able to teach for 25 years."

Sandra Stotsky, Greatwood's instructor at Harvard the past two summers and her adviser on the book project, calls Greatwood "a motivated, determined person with a helluva lot of guts. She won't just lay back and take it -- and her autobiography reflects that."

Greatwood never married, because, she says, "In my day, 'polios' just did not get married." She does not regret the decision, she says. Nor does she regret not having children. "Early on in life, I decided that the talent I had was better spread out over many kids. I've taught three or four thousand children -- helped them on their way. To affect so many lives is quite special."

Kitty Howard, a longtime friend and the former librarian at South Park High School in Buffalo, views Greatwood as "a most amazing person. She has a marvelous mind and is extremely compassionate. One of her gifts is that she makes you forget she is handicapped. She never gives you the feeling that she is any different from anyone else."

Greatwood credits her parents, with whom she lived until 1977, with instilling this attitude in her. "They were the ones who always kept me going. They never let me slip into self-pity," she says. "They were ordinary people, but they had extraordinary vision. . . . They always had a dream for me. They always made me feel special."

When not at her typewriter, the gray-haired Greatwood is on the floor, doing exercises "like Jane Fonda," or riding her three-wheeled bike.

When she finishes the book, which she hopes to keep to about 150 pages, Greatwood plans to continue giving talks about overcoming polio or any handicap to school and church groups. "To me, it is exciting to talk to children and say, 'Look, you can beat this thing,' " she says.

And after that?

"When I get to heaven," she says, "I'm going to do ballet."