David M. Rubenstein, co-founder of the Carlyle Group, atop the Washington Monument, which was damaged in the August 2012 earthquake, with Interior Secretary Sally Jewell. Rubenstein has donated $7.5 million toward repairing the monument. (Tami Heilemann )

It was the kind of out-of-the blue telephone call that do-gooders dream about.

Leslie Greene Bowman, president of the Thomas Jefferson Foundation, the nonprofit that cares for the founding father’s Monticello home outside Charlottesville, received the message when she walked into her office Dec. 11.

David M. Rubenstein would like a ring back.

Rubenstein, the billionaire financier. The Carlyle Group co-founder who paid $23 million for a copy of the Magna Carta — then gifted it with great fanfare to the National Archives. The one-man philanthropic band who was spraying more than $100 million across Washington tourist stops from the Kennedy Center to the Washington Monument, from Ford’s Theater to the National Gallery of Art, from the White House to the Library of Congress. Even the pandas at the National Zoo avoided deportation thanks to Rubenstein’s largesse.

Rubenstein is the Monument Man.

“May I visit? he asked the effusive Bowman when she returned the call.

You could see her open arms all the way from George Washington’s Mount Vernon estate, where Rubenstein was planning a $10 million gift to preserve the first president’s home.

“That would be absolutely wonderful,” Bowman said. “We can’t wait.”

Six months and a $10 million gift to Monticello later, Rubenstein — blue suited and red tied — is in his Carlyle second-floor office late in the afternoon on the first day of summer. The history buff and artifact junkie can be a chatterbox when relaxed, and he is especially expansive on a recent warm Friday. On his desk is the latest book on Abraham Lincoln. Research for another gift?

Aside from the bottle of Nantucket Nectars’s diet peach, there is little else in his office that tells you much about this ascetic vegetarian who, as a young lawyer, served as a White House domestic adviser to President Jimmy Carter. Rubenstein three decades ago saw the opportunities in leveraged buyouts, where companies were bought with borrowed money, rebuilt or improved, then sold for big profits. In 1987, he founded Carlyle Group with colleagues William E. Conway Jr. and Daniel A. D’Aniello, and all three became fabulously wealthy. They turned Carlyle into a multibillion-dollar, publicly traded financial services firm with investors across the planet.

At 63, Rubenstein has already given several hundred million dollars to charity. He has, along with Microsoft founder Bill Gates and legendary investor Warren Buffett and nearly 100 other wealthy citizens, pledged to give half his money away before he dies. A big part of that giving is his headline-making gifts aimed at American historical projects such as Thomas Jefferson’s Monticello — or what he calls his “patriotic philanthropy.”

“The patriotic philanthropy, the things I’ve done, quote, for the country, is honestly a modest amount of the money I’ve given away,” said Rubenstein, who has lectured on the Gettysburg Address. “Some people would say you are a great patriot. The patriots are the people who are the soldiers who have given their lives and their limbs. Writing a check is nice, but it’s not patriotic.”

He doesn’t mind the attention that the grand gestures bring. Like most of what he does, the so-called patriotic gifts have an ulterior motive: to inspire others to follow his example.

“If I can do a public-private partnership at the Washington Monument, I hope other people will say, ‘Why can’t I give money to other public works sites in the United States which need help?’”

The love for Washington and democracy, and the monuments to both, run deep. He read voraciously when he was a child in Baltimore, the only child of a postal worker and retail saleswoman. His favorite topic was history. His mom recalls ferrying him around Washington to view the monuments and ogle the centers of power.

“He was was very, very impressed with the White House, the monuments, the State Department,” his mother, Bettie, recalled. “That had a lot to do with it.”

As Rubenstein puts it, “I live in Washington. I met my wife in Washington. I raised my kids in Washington. I’m an American. And when you get to be fortunate, you should give back to people. And I’m giving back ... because my country enabled me to do this. If you grew up anyplace else and your last name is Rubenstein and you came from a very modest background, you probably wouldn’t have had the chance to rise up. Here, I’ve had the chance to rise up and get to be wealthier than I ever dreamed possible.”

Not much of this is random, even if Rubenstein himself admits he sometimes stumbles through the process. After two decades of building Carlyle, he expanded his focus at age 54 to what he would do with the fortune he accumulated after reading that men his age typically have a life span of 81. He did the math and decided to get started.

The turning point was the Magna Carta, which Rubenstein purchased during a blind bidding process at Sotheby’s in New York City.

He sat in a closed room, where he bid on one of several original copies of the famed document, which England’s feudal lords forced onto the king in order to establish their rights and limit the sovereign’s powers.

After the sting of writing the $23 million check, he felt pretty good about himself and set out to give more.

Philanthropy can take many shapes. Rubenstein’s colleague, Bill Conway, the investment brain of Carlyle, is also giving away much of his fortune. But he has taken a different approach, targeting the homeless and hungry, and asking for public suggestions on what he can do.

The much wealthier Gates, meanwhile, wants to rid the world of malaria, fix education and deliver proper sanitation to billions.

Rubenstein keeps his own counsel. He studies. He has read biographies of Andrew Carnegie (“who invented modern philanthropy”) and John D. Rockefeller (“he took it to the nth degree”) for ideas.

“I don’t have enough money to solve the poverty of Washington, D.C.,” he said. “I’m never going to get that kind of money. I don’t have the money of Bill Gates. I don’t have the money of Mike Bloomberg. And I don’t have the money of Warren Buffett. I have a constrained amount of money compared to them.”

So Rubenstein has learned to focus on things where he gets pleasure, but can also have an impact.

He has given millions to fight rare-but-deadly diseases such as pancreatic cancer and amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease. But he has also treated other giving like one would venture capital: He seeds philanthropic proposals with a grant. If they take off, he might supplement the gift to speed up the progress.

What he doesn’t want to do is endow something that is going nowhere.

“Suppose they are not that good at what they are proposing or suppose the money doesn’t do any good. Then I’m stuck with that endowment money sitting there, I would rather give them operating money, let’s try it for a couple of years, see if we can make a big impact, and see if it works.”

Wendy Woods, senior partner at the Boston Consulting Group and the global leader of the firm’s social impact practice, said there are different advantages and disadvantages on whether to fund endowments or make high-impact gifts.

“The short-term funding model usually gets more funding to the organization faster,” Woods said in an e-mail. “From the perspective of the individual giving, they can best direct and focus the use of their funds. They get to see more of the benefits, the difference that their gift makes — that also often creates a willingness to give more. The difficulty becomes if the donor’s goals for the organization are not well-aligned with the path, the strategy of the board and the leadership of that organization.

“In terms of an endowment, the benefit is that this creates longer-term stability for the organization,” Woods wrote. “The opportunity to create good now is usually more limited ... but the ability of the organization to thoughtfully plan and deliver consistently over a period of time is greater.”

Rubenstein has no foundation. No adviser. No staff. He wants his results now.

“I just think of what I want, and then I do it.”

Like when he took pity on the musicians at Baltimore City College, where he attended high school, and whipped out his checkbook on the spot and gave them $100,000 for new musical instruments.

To handle formal requests, he schedules one-on-ones on Saturday mornings — when he is not on Carlyle time — at the Four Seasons Hotel in Georgetown, where those seeking gifts are given an hour to make their case.

Solicitations for his money come from far and wide — he once was asked to fund a Nebraska library — and are often masked as a “request for advice.” One letter-writer asked for $50 million to endow a charity on the basis that his father was a guidance counselor at Rubenstein’s Baltimore high school.

Although he cops to having an ego and doesn’t mind adulation that comes with his name on the buildings at Duke University, Johns Hopkins University and elsewhere, he get satisfaction just meeting the parents of Washington high school students who have received Rubenstein-funded college scholarships from the Economic Club of Washington, which he chairs.

After he a concludes a short exegesis on the origin of the word philanthropy, which comes from the Greek “loving humanity,” Rubenstein sits back at his office conference table and defines his own philanthropy.

“I give money, because I recognize that’s part of the game. Two, I give my time. And third, I wanted to do something I learned to do at Carlyle, which is to help [organizations] raise money.”

At the moment, he is chairing or co-chairing six major national fundraising campaigns at Harvard University, the University of Chicago, the Smithsonian Institution, the John F. Kennedy Center for the Performing Arts, the Kennedy School of Government (again at Harvard) and the National Trust for the National Mall campaign.

He is hoping some of his fundraising skills rub off on the organizers of those groups. After all, the Rubenstein money trough will not be around forever.

Some day, he won’t be around. And like the good financial engineer, his philanthropy is a hedge even on his afterlife.

“Though you cannot buy your way into heaven, why take a chance?”