The Chinese Emperor Yao was disturbed by his young son's inability to concentrate. So, legend has it, the ancient ruler asked an adviser to invent an activity that would condition the boy's mind. The result: a wooden board and two boxes of stones.

Thus was born "go," one of the oldest and most complex board games on the planet. Part sport, part mystical experience, the 4,000-year-old tradition has attracted followers who are a rare combination of strategists and seers. An increasing number of Western devotees include celebrities Robin Williams, Paul Giamatti, and Rod Stewart.

Locally, go evangelists congregate at about 10 clubs and societies scattered throughout Philadelphia and its surrounding counties. The players are a mixed bunch, ranging from curious kids to an older Chinese player at the Phoenixville Go Club who - according to his opponents - knows little English outside the words "you lose."

At these gatherings, the goal is to promote the game to newbies while giving fans a place to play with open and unapologetic zeal. At last week's U.S. Go Congress (what's considered the American go Olympics) at George Mason University in Fairfax, Va., evidence of the game's growth, especially among younger enthusiasts, was apparent.

"My conference in most normal years is about 20 percent youth. This year, it's about a third," said Todd Heidenreich, director of this year's congress, which drew about 500 people, including professionals from Japan, China, and Korea.

At the opening ceremonies, Matt Bengtson, copresident of the Penn Go Society at the University of Pennsylvania, played a piano duet with his friend Haskell Small, who wrote the music to accompany video of a game between two go masters. "It's an extraordinary experience," Bengtson said of the gathering - a standard response from the go tribe. It seems you don't just play the game. You get absorbed.

The basic principles of go are simple. Each player has a bowl of either black or white stones, which are placed in turn at intersections on a 19-by-19-line grid. The object of the game is to win the most territory by surrounding and capturing as many of the opponent's stones as possible. The game ends when both players decide there are no more possible moves. Because of the size of the grid and the simplicity of the rules, the game has an extensive range of possibilities. Go experts contend there are more possible games of go than atoms in the universe.

It's the seemingly infinite range of strategic moves that has intrigued science types. In 1996, IBM's Deep Blue computer beat the 1985 world chess champion Garry Kasparov at his own game, but computer scientists have yet to build a machine that can beat a professional go player on a full game board.

"There's a saying that it takes a minute to learn to play but a lifetime to master, and I would say that that saying is very, very true," said Peter Nassar, former copresident of the Penn Go Society.

Craig Brown, a member of the Phoenixville Go Club, takes go to the public every Saturday at his local farmers' market. Next to the tables of basil, cabbage, string beans, and cinnamon rolls, children and adults bend over his boards to learn the ancient game.

Nathaniel Bryant is already an old hand. He's 7.

"[Brown] taught me how to play and then I got the hang of it," he said.

For Brown, an admissions officer at a special-needs community in Chester County, the game is both relaxing and exciting.

"It's a really weird feeling," he said. "It feels meditative, and yet it feels very competitive at the exact same time. There's nothing for me that does that other than go."

At the Phoenixville Go Club's Wednesday night gatherings at the Artisan's Cafe, attendance has been growing steadily since the sessions began a little more than a year ago. Christian Morrow, 14, who is home-schooled in Wayne, took up go two years ago and has honed his skills at Artisan's.

"There's endless strategies. I mean, people who devote their lives to it can never fully comprehend how much depth there is to this game," he said.

Where did all this love come from?

One source is a Japanese print and TV comic series called Hikaru No Go, which chronicles a young player's quest for go glory. The series, which first appeared in Japan in 1999, compelled some children to discard their video games for long hours spent in local clubs learning from masters. Eventually, the series migrated here in print and on DVD and created interest among children, teens, and college-age followers of Japanese manga.

The series has given a youthful kick to a game traditionally played by an older crowd. With a new generation of players on the Internet, 25 U.S. colleges and universities now have student-run go clubs. And at Feng Yun's 7-year-old go school in northern New Jersey, her students include almost 100 registered members of the American Go Association who are 22 or younger.

Enthusiasts insist that go's visual nature gives it an edge over other strategic games, such as chess. Go boards are always made of wood. The stones create patterns that are both elegant and strategically informing.

Brian Atkins, a Phoenixville Go Club member, likes how the board conveys both mathematical and aesthetic properties. "I like the way everything looks together and how there's a whole scheme you can see."

Brown echoes that appreciation.

"I think it looks incredibly cool with the circles, the squares, the lines, the wood and stone," Brown said. "When I play, I can easily sit down to a game and look up, and four hours have gone by."

Rightly so. This slow rhythm and meditative quality reflects elements of Japanese, Chinese, and Korean culture. In fact, the game is said to be an easy introduction to the spirit of the East, promoting Confucian virtues of propriety, wisdom, and human-heartedness.

Early on, astrologers became interested in the game and attributed Taoist symbolism to it. According to The Classic of Go, written in the 11th century by Chang Nui, the 180 black and 180 white stones were a metaphor for the balance of yin and yang in the cosmos. The concept is, well, deep.

"If there is intelligent life elsewhere in the universe," said chess grandmaster Emanuel Lasker, "possibly they have discovered chess. Certainly, they have discovered go."

If You 'Go'

The Penn Go Society meets Wednesdays at 5:30 p.m. in the lobby of the Creese Student Center, Drexel University, 3210 Chestnut St., during the summer, and at Houston Hall, University of Pennsylvania, 3417 Spruce St., from September until May. For details, go to http://chapters.usgo.org/penngo/. The Phoenixville Go Club meets Wednesday evenings at 6 p.m. at Artisan's Cafe, 236 Bridge St., Phoenixville. For details, contact Craig Brown at scorelessdraw@gmail.com.

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