Heart.
In the physical sense, it is one of the organs most critical to keeping us alive. Yet one cannot describe how much greater the impact the literal heart makes in giving us reason to live.
While surgeons were able to repair the hole in the heart of Patriots linebacker and former Arizona football star Tedy Bruschi - a hole that caused Bruschi to have a stroke in February - all the surgeons in the world could never repair the hole still left in Bruschi's life.
The sport that had become a part of who he was still called to him, and Bruschi answered, returning to practice for the first time this season last week after being cleared by multiple team and private doctors.
Football could never be more important than his wife and three young children, whom Bruschi had trouble seeing after his stroke blurred his vision for a few months during his recovery. But with a few good years of his career ahead of him, Bruschi could not so easily be content by filling that football hole in his life with watching from the sidelines.
Bruschi continues to practice with the Patriots' first-string defense in preparation for their game Sunday against Buffalo, after having a bye on Oct. 23.
The 32-year-old Bruschi has been filling holes his entire sporting career, intimidating running backs and quarterbacks alike as a huge part of Arizona's ferocious "Desert Swarm" defense from 1992-95, before plugging up gaps for the two-time defending Super Bowl champion New England Patriots and as a first-time Pro Bowl selection in February.
Bruschi was a legend at Arizona, swarming the field to make tackles, with a chant of "BRREWWWWWWWSKIIIIIIIIIIIII" sure to follow the announcer's voice every time Bruschi had just grounded another opponent.
Fans in the stands actually looked forward to defense on the field, and not just because the offense was so bad that it was unbearable to watch.
In the Dick Tomey era in which Bruschi played, Arizona was renowned across the college football world for its defense, garnering high accolades, including being picked as the preseason No. 1 in 1994, with Bruschi and other members of the Swarm gracing the cover of Sports Illustrated.
People knew names of the defenders back then and recited them with pride. Bruschi, Bouie, Salave'a, Sanders and Waldrop highlighted a Wildcat defense that gave opposing teams' offensive coordinators nightmares weeks before the game.
Under John Mackovic, the Desert Swarm became the Desert Lukewarm.
Defense was traded for offense, as Mackovic was contented to let Jason Johnson, now a third-string quarterback for the Canadian Football League's Edmonton Eskimos, air out the ball in what became a Wild West-type shootout that Arizona lost more than it won.
Even now under the leadership of defense-minded head coach Mike Stoops, the Arizona defense still lacks the big names that it once had under the Desert Swarm. The fans have seemingly forgotten Tomey's style of play, which kept Arizona competitive, if not good, for his entire tenure at Arizona.
The Wildcats do not need freshman quarterback Willie Tuitama as much as some people would think (although I will give it up to him for having a great game against Oregon).
What they need is a leader on defense, one who makes a name for himself for an entire year, with other guys stepping up around him to inspire fear, rather than moderate respect, from opposing offenses. A guy like Bruschi. A guy who can't be kept down, who holds a burning desire to play the game he loves, not a lustful passion for the money the NFL pays him to play it.
Think of any quarterback in the 1990s at Arizona who ever went on to do anything. Better yet, make it the $1,000 "Jeopardy" question - name two Arizona quarterbacks who played anytime between 1990 and 1999. Give up?
Try names like George Malauulu, Dan White, Brady Batten and Keith Smith. The only one who may ring a bell was Ortege Jenkins, made famous by his last-second, end-over-end flip into the end zone to beat Washington.
The point is that Arizona had some of its best football teams in the '90s, and the offense certainly wasn't the reason why. If we want to build our program back to prominence, Stoops has got to stop placating the fans by trying to garner big-name offensive recruits and do what he should do best: Rebuild our defense.
There are guys who have been good in spots: Darrell Brooks, Copeland Bryan and Dane Krogstad, to name a few. And it is true that the Wildcats' defense has been devastated by injuries all year long, making it tough for the guys to build up that solid "D" we so desperately need.
Yet it simply comes down to having guys with flat-out heart for the game.
Bruschi couldn't be kept off the football field for long because once his physical heart had been healed, his heart for the game carried him the rest of the way.
"There were times, in my mind, I thought I was done," Bruschi said to reporters at a news conference on Oct. 17, according to The Associated Press. "If I could express to you what this means to me (to return) I would, but I don't know if I really can."
To build a championship-caliber team, we need more guys like Bruschi - guys who have the heart of a champion.
Adam Gaub is a journalism senior. He can be reached at sports@wildcat.arizona.edu.