BALTIMORE — The School Sisters of Notre Dame imagine that there is a special place in heaven for the man who helped their Roman Catholic order’s international teaching and ministry and its work with the poor.

“He was such a private man, a wonderful, kind and gentle man, so we all decided that he probably wanted his name to be confidential,” Sister Kathleen Cornell, the leader of the order’s Atlantic-Midwest province, said. “So it will be our secret. But, of course, God also knows the gift that he gave us.”

When the man died of cancer last Feb. 3, donations to the nuns were requested in lieu of flowers. He also bequeathed to the nuns his estate, worth more than $1 million, including a 100-year-old Honus Wagner baseball card. The nuns were not surprised that the man remembered them in his will because he cared so much for the church and, at 85, had no immediate family.

The nuns were surprised, though, to find the card in a safe deposit box with a typewritten note attached: “Although damaged, the value of this baseball card should increase exponentially throughout the 21st century!”

The donor, the brother of a deceased nun who belonged to the order, knew his T206 series Honus Wagner card was rare. Produced from 1909 to 1911, about 60 are known to exist. One in near-perfect condition sold for $2.8 million in 2007, a record price for a baseball card. The nuns’ Wagner card was sold for $220,000 last month.

When the man acquired the card in 1936, the order — established in 1833 in Germany — was much more robust. Now the median age of the sisters is 76, and membership has dwindled to 3,500 in 31 countries.

Sister Vincent — the donor’s sole sibling, the nuns said — entered the order when she was 21. She grew up in New Jersey, then earned doctorates in physics and mathematics from the Catholic University of America, in Washington. Later, she taught at the College of Notre Dame of Maryland.

After a brain aneurysm in the 1990s, Sister Vincent was cared for here at Villa Assumpta’s infirmary, where her brother often sat at her bedside. The nuns knew him well. He had lived in Englewood, N.J., and had worked for the Ford Motor Co. in New York before moving to Stewartstown, Pa., to be closer to Sister Vincent. She was all he had; he never married and had no children.

“They were so devoted to each other,” Sister Bernice Feilinger said. “He believed in our mission and was so proud of his sister. His eyes would light up whenever he talked about her.”

After Sister Vincent died at the age of 77 in October 1999, he continued to visit on Sundays, often in a green sports jacket and tie. He would attend Mass and take some sisters to lunch, Feilinger said.

He disliked talking about himself, the nuns said. But they do know he was meticulous: In his safe deposit box was $1,000 and a note saying it was a safety net for any Y2K bank glitches.

After picking up the baseball card, Sister Virginia Muller, the order’s former treasurer, searched the Internet to determine its worth. When she saw the value of other Wagner cards, her jaw dropped.

“I very carefully put it into the back of my files,” she said, laughing. “Then quickly insured it.”

Wagner, a shortstop for the Pittsburgh Pirates nicknamed the Flying Dutchman, was one of the first five players inducted into the Hall of Fame. He was featured on the T206 card produced by the American Tobacco Co. only briefly because, some sports memorabilia experts say, he did not want to promote tobacco products to children.

“I would say eight out of 10 times someone brings us a Honus Wagner card it’s counterfeit, so we were skeptical about this one,” said Derek Grady, director of grading for Sportscard Guaranty, which authenticated the card. “It was real, but in very bad shape. If it wasn’t trimmed down, creased and shellacked, it could have been worth a million dollars.”

Long before the card was sold, sports were popular at Villa Assumpta, which houses about 75 retired and ill nuns. In the common room, baseball and football games are often shown on the big-screen television. The local teams are the favorites, with some nuns sporting team colors on game days.

Sister Mary Agatho Ford, who died at 100 in 2003, had received a signed photo and baseball from Cal Ripken for her 98th birthday. They are displayed in a glass case next to other cherished items, including chalices that deceased sisters held dear.

The company that sold the Wagner card, Heritage Auction Galleries in Dallas, had told the nuns to expect it to bring $150,000. But as soon as their story went public, the card grew in value.

“Provenance is always important in collectibles, and the nuns provided a neat background story,” Chris Ivy, director for sports auctions at Heritage, said.

In November, a sports memorabilia store owner won the auction by bidding $262,900, including a $42,900 commission. But he never paid the money.

So just before Christmas, the auction house offered the card to Nicholas DePace, a cardiologist in the Philadelphia area who is one of the nation’s top sports memorabilia collectors. He bought it for $220,000, and the nuns received every penny. Two days later, Heritage called DePace to ask if he wanted to quickly resell the card for a $60,000 profit.

“I said, ‘What’s the matter with you guys?’” DePace said. “It’s no longer just a baseball card; it’s become a religious relic, a St. Jude of memorabilia. I’m keeping it.”

DePace said that his archbishop would bless the card and that its eventual home would be a nonprofit sports museum he plans to open in Collings- wood, N.J.

Muller said Wagner’s granddaughter called to say she was thrilled that the card had helped the nuns.

“I wish I knew more of the story, like where he got the card or why he kept it,” Muller said of the beloved donor. “But I guess it will remain a mystery.”