Graceful exits are scarce in professional sports, maybe because it's usually someone else telling you it's time to go. For those whose final act on a football field is to be carted off to a round of bittersweet applause, you'd think it might be particularly agonizing to say goodbye.

Jim Davis/Globe staff photo

Rodney Harrison without fire? Unthinkable. That's like Derek Jeter without calm eyes. Once an athlete's definitive characteristic is diminished, the characteristic that made him superior to the rest, what's the point of playing on? Kudos to Harrison for recognizing that his internal flame was not eternal, that the fire that made him one of the finest (and most fined) safeties of his era was down to a flicker.

So, yes, it was time for him to go, and even those of us who held out hope that he would pass the early weeks of the season on the Junior Seau Taxi Squad while waiting for Bill Belichick's bat signal that it was time to come help the ol' gang again can admit it. Harrison's career is in the past tense as of today, and so our attention turns to his legacy, his place in Patriots lore.

There are countless Patriots of this golden, glorious era who will be remembered fondly, but only a few will become certified legends. Tom Brady is at the head of that class, obviously, and the educated hunch here is that Harrison will also belong in that group. Some might remember Ty Law or Mike Vrabel or Tedy Bruschi or even Richard Seymour as the signature player of the Patriots' championship defenses earlier this decade. Some will say the Patriots didn't have a signature defensive player, that their success was the result of their strength as a whole. But in my mind, and maybe yours too, no other player epitomizes the fierce and smart defenses of the Patriots dynasty like Harrison.

He was as intelligent as he was vicious, making up for his underwhelming speed with a deep knowledge not only of his own defense, but of the opposing offense. He was versatile, becoming the lone player in NFL history to compile more than 30 sacks and 30 interceptions. He was an absolutely carnivorous tackler, cruelly batting around opposing receivers like a cat tormenting a captured mouse just for the sport of it. He was the glue, particularly during the 2004 championship season when the defensive backfield was decimated to the point that wide receiver Troy Brown took a spin at cornerback. He was Exhibit No. 37 of a player you love on your favorite team and absolutely loathe as an opponent. (Kevin Youkilis is also a classic example of that phenomenon.) I suspect Lawrence Taylor still ranks at the top of Belichick's list of his favorite defensive players he has coached, but Harrison has to be a finalist for that coveted runner-up slot.

When you consider Harrison's time here and the literal and figurative impact he made, it's almost easy to forget that he was still a San Diego Charger when the Patriots won their first championship, spending the first nine years of his career there after arriving in the league as a fifth-round draft pick from Western Illinois in 1994. But it feels like he's been one of ours all along. He essentially replaced Lawyer Milloy at safety, though they were teammates in camp in 2003 before the hard-headed Milloy's stunning release for refusing to restructure his contract. Patriots fans adored Milloy, barely noticing even as his production diminished to virtually nothing, and the uproar regarding his departure only grew louder when he signed with the Bills and promptly helped them whup the Patriots in the '03 season opener. But it did not take long -- a week, maybe two, certainly no more than a month, right? -- to realize that Harrison was the superior beast, a legitimate Hall of Fame-caliber, hard-hitting strong safety. He was everything we always wanted Milloy to be.

The man's legendary toughness was no myth, either. The defining moment of a career marked with highlights came last in the Patriots' Super Bowl XXXVIII victory over the Carolina Panthers. Here's how Tedy Bruschi, a dude who knows a little something about toughness himself, remembers it:

"He broke his arm and didn't come off the field, he played the next play, made the tackle on the next play, and then it completely broke," Bruschi said. "He went and got the air cast on and said, 'I'm not staying in here, let me go back out there.' "

In the end, his hell-bent style of play took a toll on his body, and it became harder and harder for him to "go back out there." Over his final four seasons, he played in just 31 games, though four of his game-day absences were because of a suspension for violating the league's substance abuse policy after purchasing human-growth hormone, the great embarrassment of his professional life and one for which he made no excuses and all the requisite apologies.

In a way, the final scene of his career was perfectly appropriate. In Week 7 last season, Harrison tore his right quad while trying to line up a hit on scrambling Denver Broncos quarterback Jay Cutler. No longer as fast or as agile as he was in his prime, he got tangled up on a fake and a juke; in his younger days, you can be sure he would have knocked that emo mop off Cutler's head. Instead, he got carried off on his shield, waving in between winces to the knowing and appreciative Gillette Stadium crowd.

It was his first goodbye. Today brought his last.

And yet I know I'm not the only one who finds himself reminiscing again and again about all the wonderful moments Rodney Harrison provided in the six seasons since he said hello.