Once a child prodigy who at age seven performed for the Kennedys, Ma has gone on to receive 15 Grammy awards and record over 90 albums.

Along the way, he has literally set the tone for some of the most significant moments in recent U.S. history, namely as the first performer to accompany the 2002 reading of the names of the victims of the World Trade Center attack and by performing at the inauguration of President Barack Obama in January of this year.

(Yo, by the way, translates -- twice -- as “friendship,” and Ma jokes that after his parents named his older sister, also an accomplished musician, Yeou-Cheng Ma, they got lazy and simply went with two Yos.)

Early in his career, he was lauded for his performances and renditions of Johann Sebastian Bach’s cello suites, Johannes Brahms’s cello compositions, and other classical, well, classics. But it’s his crossover appeal via contemporary collaborations and ventures into pop culture that has led to his accessibility and boosted his longevity.

He has appeared on Sesame Street and Mister Rogers’ Neighborhood, been animated on The Simpsons and Arthur, and done a cameo on The West Wing. He’s contributed to the soundtracks of numerous films, including those for Seven Years in Tibet and Memoirs of a Geisha. And that haunting accompaniment to the lovelorn warriors and their encounters amidst the treetops in Crouching Tiger, Hidden Dragon? All Ma. He most recently put his work on the site Indaba Music to let fans interact with it, and there are also more than 2,000 YouTube selections featuring him to ponder (his Internet presence only adds to his accessibility). And yes, he also has a Facebook page.

Last month (the month of his birthday), his recording label, Sony, put all his work together in a 91-CD boxed set. The collection, “30 Years Outside the Box,” celebrates Ma’s three decades with Sony and features two CDs of previously unreleased material, including the inauguration theme for President Obama, “Air & Simple Gifts.”

“I see Tiger Woods as the Yo-Yo Ma of golf,” says conductor David Zinman, giving an analogy that places Ma in the context of other well-known all-time greats. Staying with sports analogies, Michael Jordan would be the Yo-Yo Ma of basketball, Roger Federer the Yo-Yo Ma of tennis, and so on.

Onstage, Ma is athletic in his undulations. He sits on the edge of his seat, his arms reaching around to caress his cello, the fingers of his left hand seemingly everywhere on the strings at once. (He wears his wedding ring on the right hand in order to avoid contact between it and the cello.) His bow hand defies geometry while his head bobs and his foot taps. As he sways from side to side, his mouth alternates between an intense frown and a half-agape snarl that shows his front teeth. His eyes open, close, and flutter, and at times, he comes fully out of his chair as the music itself defies description.

And that’s just during the rehearsal for his performance in Azul: The Soul of Argentina with the Atlanta Symphony Orchestra. Wait until the real show begins.

When he’s done practicing, Ma reveals that it was a decidedly nonmusical occurrence in his life that ended up inspiring most of his ambitions and kept alive the fire that led him well past the pressures and occasional failings of child prodigies. He is funny and engaging -- almost impish -- but also very philosophical and more willing to impart the big picture than he is to chitchat about the number of cellos he owns ( just a few) or the languages he speaks (three).

“Anthropology became a world-changing experience for me,” he says. “It opened me up to a much bigger stretch of humanity that I really didn’t have access to or direct experience with.” This happened at Harvard University in the 1970s, when Ma, at age 17, decided to pursue a liberal-arts education, having studied music at Juilliard’s Pre-College Division. His wife is a former Harvard instructor, and together they have two grown children.

Born in Paris after his parents emigrated from China in the 1940s, Ma first learned music from his father (who had a PhD in musicology), although he didn’t pick up the cello until age four. “It’s just something I happened to be good at or had a facility for at an early age, and there’s no kid who doesn’t want to be good at something. I liked music, but it wasn’t ‘Be a musician or bust.’ [First,] I played violin, but apparently I wasn’t very good at it. I wanted to play double bass because I thought it was huge. I can give you every rationalization of why the cello. It’s a really nice instrument. It mirrors the ranges of the human voice, for example. But because I started so young, I didn’t have to make the decision like, ‘This is what I must do.’ ”

When he contemplates his career and the sheer scope of the boxed set, Ma goes straight to the heart of it: “It’s all fairly organic. In every chapter of my life, there were different kinds of stimuli. … In my 20s, I felt lucky [that] I had chances to play -- and I was seeing many parts of the world for the first time. Then in my late 20s, I got married, and then the children came along, which makes you more empathetic to the world. In my 30s, it was about exploration -- exploring with friends of mine who were a couple of decades older, who had access to a different history, snapshots of the world we can’t see anymore from people who can report it because they’ve been there. It’s a kind of curiosity. In my 40s, I started to think more about … ‘What, really, what is it all for?’ ”

Ma thankfully found the answer in 1998 with his founding of the Silk Road Project, which has allowed him to merge his passion for anthropology with that for his music.

Historically, the Silk Road was the name given to the land and sea trade routes of Eurasia that crossed from the Pacific to the Middle East to the Mediterranean between 2000 BC and 100 AD. Goods, cultures, religion, and musical instruments all intermingled.

Ma refers to the trade routes as the Internet of antiquity, and his nonprofit Silk Road Project has set a similarly ambitious course to connect people. To date, some 60 Silk Road ensemble performers have played in 25 countries and produced three albums and 30 commissioned works. The in-house ensemble numbers 41 artists and 19 composers. Recently, the project expanded to include giving workshops in New York City public schools, with the hope of expanding to Chicago and beyond.

Through the Silk Road Project, Ma has combined a world’s worth of sights and sounds, thus, in a way, merging anthropology and archaeology. “I’m reporting things, and what I’m reporting, hopefully, is a kind of advocacy for a person or a state of mind of the world [that contextualizes] a time period, whether it’s our time period or some period of the past or maybe the future. I think of it as the coding of music, the coding of sounds that actually gives access to areas that are both verbal and nonverbal. My interest just comes from trying to figure out who said what and why. Why do people act the way they do and code something in sound? What was their motivation?”

The project has been roundly embraced, with financial assistance being provided by everyone from the U.S. Department of State to the Aga Khan Trust for Culture. In fact, it has been so successful that in 2002, Ma was appointed a CultureConnect ambassador by the U.S. State Department, and in 2006, he was named a Messenger of Peace by the then secretary-general of the United Nations, Kofi Annan.

That the Silk Road Project reflects Ma’s ambition and energy is evidenced by its touring schedule. Stops are planned in England, Belgium, Germany, Switzerland, and Romania for the end of this year, and then for the spring of 2010, events have been planned in Singapore, Taiwan, South Korea, and Macao. Ma’s “regular,” performance schedule is just as demanding: Between February 26 and June 6 of this year, he played 23 concerts in 18 cities worldwide.

“I believe very strongly in working toward understanding and creativity in the cultural realm. Silk Road is not exclusive to culture, but if we can understand the workings, it can help in other ways,” he says. And that’s why he didn’t hesitate to play in Syria when the opportunity presented itself or think twice about playing with the Iraqi National Symphony Orchestra.

“Accessibility is having an empathetic understanding of someone else’s world and communicating what you have to communicate. The most important thing we can do as humans and enlightened people is to be empathetic. … Things happen so quickly, like the financial market’s meltdown or climate change or swine flu. How can we live in a world without a lot more empathetic understanding? We are responsible for actions that go beyond ‘what is good for me?’ and ‘I’m not hurting anybody.’ My greatest passion is people.”

There’s a reason that music has been called the universal language -- it soothes the savage beast. Which is exactly what Yo-Yo Ma wants.