While delivering opening remarks at Winsor School in September 1986, Virginia Wing quoted part of a prayer that her father, a Unitarian minister, had written.

“We belong to the believers of the world,’’ she told the girls who would fill the classrooms at the school she had directed for nearly a quarter-century. “We belong also to the doubters of the world, those who have dared to question, to criticize, to evaluate, to seek truth.’’

A steadfast presence at the school, where she was a teacher and then the director from 1952 to 1988, Miss Wing was both a believer and a doubter — and she was unafraid to raise questions at a key time more than three decades ago when many private schools faced financial pressures. Winsor’s board considered forging a coordinate agreement with Noble and Greenough — a step ­toward becoming de facto co-ed.

“At the last minute, she realized that was a huge mistake and stopped it,’’ said Sarah Pelmas, Winsor’s current head of school. “That decision is probably the single most important thing that happened to Winsor in the 20th century.’’

Miss Wing, whose belief in single-sex education helped keep Winsor an all-girls school in Boston, died Feb. 5. She was 94 and lived in Cambridge.

“She fought these really fierce fights at a time when women weren’t supposed to be that fierce,’’ Pelmas said.

A single-sex school gives girls “an opportunity to grow at their own pace. I think there is no concern about making an impression on the boys,’’ Miss Wing said in a 1987 interview with The Winsor Bulletin, a few years after the decision to remain girls-only.

“It’s become almost a cliché, but there’s no doubt that the leadership roles in a single-sex school are wonderful for the growth of girls,’’ she added. “They don’t settle for thinking the best they can be is secretary of an organization.’’

Miss Wing “was a woman of great courage — she really was. She was not at all reluctant to take a stand on something if she regarded it as right and fitting and moral to do so,’’ said the Rev. Tony Jarvis, a longtime friend and headmaster emeritus of Roxbury Latin, on whose board she served. “She spoke the truth with clarity and without apology.’’

Jarvis added that Miss Wing “was a private, old-fashioned New Englander, but she had an enormous love of her students and of her school. She cared about them passionately — in fact, she devoted her whole life to Winsor School.’’

As director, Miss Wing “was a formidable woman and she ran a tight ship,’’ said Kate ­Baker-Carr of Brookline, who graduated from Winsor in 1980 and became a longtime friend.

Though Miss Wing held students to high standards, she also “was clear about giving people the benefit of the doubt and asking questions to flush out what might have been overlooked,’’ Baker-Carr said. “She was very good at asking, ‘Well, have you looked at it from this perspective?’ And the answer was always, ‘Not yet.’ ’’

Miss Wing “cared about us deeply, but whenever we had erred or strayed, we received a handwritten note,’’ Baker-Carr recalled. Miss Wing signed those missives “Ivan T.’’ – short for Ivan the Terrible. “It was a nice way of saying, ‘You’re on a little bit of thin ice.’ ’’

Virginia L. Wing was born in Springfield on May 14, 1923. She was young when her parents, the Rev. Charles A. and Katherine L. Wing, moved to Colorado intending to stay for a year. They remained for nine, and Miss Wing graduated from what was then the Kent School for Girls in Denver.

She went to Smith College and received a bachelor’s degree in 1945 after majoring in philosophy and minoring in English, an approach she said offered more latitude for taking courses she liked in both disciplines. Because her father was a Unitarian minister, “there was a tradition of going into the service professions,’’ she told The Winsor Bulletin, but she only seriously considered teaching as a senior at Smith. She wanted to spend time with friends in Denver, so she worked at Kent as an English teacher and librarian.

Miss Wing stayed four years before heading back to Smith to serve as associate director in the college’s admission office. In 1989, she was awarded the Smith College Medal, which is presented to alumnae whose lives and work exemplify “the true purpose of a liberal arts education.’’

Arriving at Winsor in 1952, she began her 36-year tenure, including 25 as director, by teaching sophomore and junior English. In 1963, Miss Wing became Winsor’s fifth leader, and during her tenure the school integrated. She also served on boards of other private schools, and was a leader of national and regional private school education organizations. The Winsor School library is named for her, as is a teaching award. She was long an advocate for higher pay for teachers.

What makes for a good teacher? Liking and respecting students, she said in 1987: “I’ve had people with absolutely impeccable academic credentials come to see me and it’s very obvious that they have no real feeling about youngsters.’’

Miss Wing did, however.

“She remembered everything, just everything,’’ Baker-Carr said. “She knew our siblings’ names, and whether or not they went to Winsor. She knew our cats’ names. She knew us. We probably didn’t appreciate the fullness of that when we were there. She knew that each of us had our gifts and struggles, and we were all going to do just fine. In my opinion, she knew how to find the best in each of us.’’

A celebration of life will be announced for Miss Wing, who leaves no immediate survivors.

At Winsor she was known for her love of cats, particularly large Maine coon cats. During the 1987 interview, the one she owned was 19. She called him Loki, “for the god of mischief.’’

She added in the interview that she had inherited a love of reading from her mother.

“All my life I’ve loved to read,’’ she said. “Before I could read, my mother used to read aloud.’’

Because of work demands, she indulged in recreational reading during summer vacation, when it was a “standing joke’’ that while preparing to leave in August, “I can hardly get into the car because I have so much piled up. Some of the fun of it is to reread the authors nobody bothers with any longer — like Trollope.’’

Miss Wing also was remembered for the stylish notes and letters she wrote, and for her choice of pen.

“She has the most impeccably gorgeous handwriting,’’ Pelmas said.

“And she always used a black Flair pen,’’ Baker-Carr said. “The same pen that signed our report cards, that sent us notes, that turned into Christmas cards and letters — the same pen.’’

Miss Wing remained active into her 90s, driving alone and going out to lunch with friends such as Pelmas, to whom she offered advice about running Winsor School. “The very last thing she said to me is, ‘It’s hard work and you have to stick with it, but there’s nothing more rewarding to do in the world.’ ’’

Bryan Marquard can be reached at bryan.marquard@globe.com.