Maybe he was thinking Ask not what your country can do for you, ask what you can do for your country. Maybe it was visceral, not so much thought as felt, and acted upon. We don't know because he won't say, at least not in public. Which is itself unusual. Silence is the refuge of celebrities caught in scandal, not the usual response of those caught red-handed doing good.

All we know is that 25-year-old Pat Tillman, a rising pro football player (224 tackles in 2000 as a defensive back for the Arizona Cardinals, a team record) came back from his honeymoon seven weeks ago and told his coaches he would turn down a three-year, $3.6 million contract and instead join the U.S. Army. For a pay cut of roughly $3.54 million dollars over three years.

On Monday morning, Pat Tillman "came in like everyone else, on a bus from a processing station," according to a public information officer at Fort Benning, Ga., and received the outward signs of the leveling anonymity of the armed forces: a bad haircut, a good uniform and physical testing to see if he is up to the rigors of being a soldier. Soon he begins basic training. And whatever else happened this week – Wall Street news, speeches on the economy – nothing seems bigger, more important and more suggestive of change than what Pat Tillman did.

Those who know him say it's typical Tillman, a surprise decision based on his vision of what would be a good thing to do. When he was in college he sometimes climbed to the top of a stadium light tower to think and meditate. After his great 2000 season he was offered a $9 million, five-year contract with the St. Louis Rams and said thanks but no, he was happy with the Cardinals.

But it was clear to those who knew Mr. Tillman that after September 11 something changed. The attack on America had prompted a rethinking. Len Pasquarelli of ESPN reported last May that the "free-spirited but consummately disciplined" starting strong safety told friends and relatives that, in Mr. Pasquarelli's words, "his conscience would not allow him to tackle opposition fullbacks where there is still a bigger enemy that needs to be stopped in its tracks." Mr. Tillman's agent and friend Frank Bauer: "This is something he feels he has to do. For him, it's a mindset, a duty."

"I'm sorry, but he is not taking inquiries," said the spokeswoman at Fort Benning. She laughed when I pressed to speak to someone who might have seen Mr. Tillman or talked to him. Men entering basic training don't break for interviews, she said. Besides, "he has asked not to have any coverage. We've been respecting his wishes. And kinda hoping he'd change his mind." Mr. Tillman would, of course, be a mighty recruiting device. The Army might have enjoyed inviting television cameras to record his haircut, as they did with Elvis. But Mr. Tillman, the Fort Benning spokesman says, "wants to be anonymous like everyone else." Right now he has 13 weeks of basic training ahead of him, then three weeks of Airborne School, and then, if he makes it, Ranger School, where only about a third of the candidates are accepted. "It's a long row," said the Fort Benning spokesman, who seemed to suggest it would be all right to call again around Christmas. Until then he'll be working hard trying to become what he wants to become.

Which I guess says it all.