THE WIND PICKS UP when Peyton Manning settles in at linebacker. A mid-October practice has just ended, but Manning is not finished. Something isn't right -- not enough to his liking -- and to make it right, Manning is lined up opposite rookie running back Montee Ball, posing as a linebacker, to show him exactly how he wants Ball to run a simple five-yard out route.

For all the characteristics most often associated with Manning -- his obsessiveness, his penchant for control, his unrelenting capacity for tinkering at the line of scrimmage, his unparalleled fluency in reading defenses -- his ability to teach has always been overlooked. He's a hard-ass who will quiz teammates in the middle of meetings about their assignments on a particular play. But he'll also stay after practice and pretend to be a linebacker to show a rookie how to get open. Manning waves Ball to run toward him, then jams the young back. Yes, Peyton Manning, a 37-year-old with a surgically repaired neck, jams him. As they're engaged, Ball pushes upfield, and Manning tells him what to do: Break outside the instant the defender -- in this case, Manning -- turns his shoulders.

After a few minutes, receiver Wes Welker happens by and relieves Manning at linebacker. Manning slides into his customary spot, in a faux shotgun. He calls the cadence and spins the ball in the air, emulating a snap. Welker jams Ball. Manning drops back, doing Peyton stuff -- shuffling his feet, holding the ball near his chin, standing tall in a fake pocket, releasing the ball high -- a textbook baseline from which he works his trademark artistry.

Welker, locked up on Ball, turns his shoulders, and Ball accelerates into his break. Manning hits him. They practice it again. And again. And again, as the wind picks up and slightly unwinds some of Manning's spirals. What seems like a basic route is really the quintessential Peyton Manning throw as his career nears its close: It's quick. It's precise. It takes a hell of a lot of practice, and it's unstoppable when run correctly.

And most of all, it's short.

As a Bronco, Manning is 3-0 with 912 yards and six TDs against the Chiefs. Chip Litherland for ESPN

IT'S FASCINATING TO watch legends toward the end of their careers. There's a nobility and heroism in their struggle to summon all of their tricks and wisdom and will to re-create the magic of their youth. We've seen Michael Jordan score 43 as a 40-year-old Wizard, Mario Lemieux lead the NHL in points for most of a season at age 37 and Jack Nicklaus win a Masters at age 46. But nothing compares to what Peyton Manning is doing right now. Two years ago, he couldn't throw a football 10 yards. This season he is playing at the highest level of his career -- having completed 68.5 percent of his passes with 36 touchdowns through Week 12 -- and arguably at the highest level of any quarterback ever. He has done this with orthodoxies that would make a younger Peyton sick. His passes sometimes flutter and wobble, especially beyond 15 yards. He's playing on sprained ankles that require regular MRIs. But somehow the most calculating quarterback in history is on track to set nearly every major season passing record, largely because he has stripped the vanity from his game, improvising based not only on what the defense shows him but on what his body, on any given snap, allows him to do.

NOBODY KNOWS HOW Manning does it. John Fox, the Broncos' head coach, says, "Just make up whatever superlative you want about Peyton and put my name on it." Ron Jaworski has been watching film longer than Manning has been alive, and even he admits that Manning sees holes in the defense in real time that Jaws misses on review. The statistics after 11 games contradict logic: The Broncos led the AFC in passes completed of less than 15 yards, yet they ranked first in yards per pass attempt at 8.7. That means they gain a lot by risking little, executing what can only be described as an explosive ball-control offense, which produced 429 points through Week 12, second most in NFL history after 11 games.

Manning's teammates can't explain him either. Zac Dysert, a rookie third-string quarterback out of Miami (Ohio), is two lockers down from Manning. After the Broncos took Dysert in the seventh round, his agent, sensing a huge learning opportunity, told him to write down everything Manning does-from when he arrives in the morning to how he prepares for practices as if they were games. Problem is, Dysert can't fully comprehend what he's jotting down. During one video session, Manning said he recognized a blitz call -- from 1999. Dysert almost dropped his pencil. What's he supposed to take from this? Have a photographic memory. Oh, and have a long NFL career.

The Broncos coaches tend to emphasize the technical aspects of Manning's game, the stuff that, after 16 years of combining players' hours with coaches' hours, only Manning sees. Offensive coordinator Adam Gase says that Manning no longer really reads defenses as much as confirms them. To illustrate what he means, Gase explains a play in the fourth quarter of the season opener against the Ravens. He says Manning saw "something" -- that's often the closest people can get to explaining what's going through Manning's head -- that tipped off a blitz. So Manning began his patented routine of spreading his arms and hunching over and inching toward his linemen, switching to a wide receiver screen pass by yelling "Alley! Alley!" At the snap, Manning fired a short flare left to Demaryius Thomas, who ran 78 yards untouched for six -- the definition of the Broncos' passing game. "There are a lot of things he does that other guys can't do because he's seen so much football," Gase says.

Still, that story doesn't quite do Manning justice. Nor does Broncos executive VP John Elway's explanation that Manning is "trying to separate himself" from the rest of the greatest quarterbacks in history. There's something deeper at work here. It's always been astounding how Manning can at once be an open book, an American icon whose life football fans think they know by heart, yet retain mysteries that go far beyond how he arrives at the perfect audible. He can be robotic in his discipline, yet that discipline has always been rooted in a fascinating and perhaps frightening mix of self-awareness and sensitivity. He knew his weaknesses better than a defensive coordinator, and masking them became fundamental to his excellence.

It's harder to hide them now. A rare glimpse inside Manning's head came in October, in his first game in Indianapolis since he was released in 2012. More than any quarterback in history, Manning can bottle his emotions, but as he warmed up on the field, the Colts honored him with a video tribute, reel after reel of touchdown passes. Manning tried to ignore it by throwing, each pass a little harder as the crowd rose in a thunderous ovation, as if he were trying to bury tears with each heave. Finally, he gave up.

Manning removed his helmet, waved to the crowd and started to cry. He has been honored hundreds of times, but until this moment, he had never been so publicly loved. He patted his heart. The entire scene was striking not just because he showed more emotion than after he had won a Super Bowl but because someone obsessed with controlling his image was, for the first time, vulnerable for the world to see.

I'M STANDING WITH Manning beside the Broncos' practice fields on an October Wednesday. He has just finished a workout and looks as if he could go at it again. He's more muscular than he was only a few years ago, which is somewhat surprising. I always imagined Manning would age ungracefully, like a president, prematurely gray and wrinkled, the tolls of unrelenting stress.

After all, Manning's genius has always been rooted in his willingness to be burdened. It began with the impossible expectations of being a Manning under center. It continued when he carried on the dreams of his older brother, Cooper, whose football career was cut short in college by a spinal condition. And it exploded in the NFL, as he scrolled through his mind before every snap, folding his hands into an alternative form of sign language to find the perfect play, reshaping the game as he dominated it. Which makes it all the more intriguing that Peyton Manning is prospering now because he has learned a simple lesson: how to let go.

That process began in January 2011. Manning, still a Colt, had just finished a tough season. He had a pinched nerve in his neck that was causing weakness in his right arm, sapping its strength like a leaky tire. And what haunted him almost as much as the surgeries that had failed to fix it was the unknown territory he was venturing into. "I'd make some progress but still didn't feel comfortable," he says.

He sought out many opinions from those he respects and one day was talking with Bill Parcells. Manning basically asked the old coach whether he thought he could still play, and if so, what his game would look like. Parcells was simple and blunt: "Can you still get 'em out?"

"What do you mean?" Manning asked.

Nobody knows quite how Peyton Manning does it. Chip Litherland for ESPN

Look at Jamie Moyer and Greg Maddux, Parcells said. Even as they aged, they could still get guys out, using tricks and smart. Parcells was metaphorically asking: Can you still move the chains? Can you get your team into the end zone? The conversation recalibrated Manning's mind. "It gave me a sense that, hey, maybe that deep comeback throw doesn't look the same as it did before," he says. "But maybe you can still get 18 yards a different way." It would require a level of patience and a suppression of ego that no alpha male quarterback seemed capable of. But Manning realized that letting go of his former self was his only way forward.

Then a third surgery on his neck just before the 2011 season -- causing him to miss the entire year and setting the stage for his release from the Colts -- complicated his plans. That December, he spent a few weeks with Duke head coach David Cutcliffe, the longtime quarterback whisperer to the Manning brothers, to begin his throwing rehab. One night, the two of them went outside and sprayed footballs with cold water to simulate a bad-weather game. As he threw, Manning was more than inaccurate; he was alarmingly inept. He couldn't catch a shotgun snap or grip the ball tightly enough to execute a handoff, which triggered a fear that he'd never contended with before. He wouldn't stop throwing that night, even after miss after miss, even after Cutcliffe implored him to save his strength. "He was afraid that if he stopped throwing, he would lose it," Cutcliffe says.

On the drive to Cutcliffe's house after that practice, Manning turned to him and said: "Am I doing the right thing? Am I going to be able to play effectively?"

It was the first time the NFL's greatest control freak experienced the most paralyzing loss of control that exists for an athlete: losing control over his body. He kept grinding, of course, accepting the reality that there would be good days and bad days, and by his first training camp in Denver, there were more good than bad. He ended up producing a comeback for the ages, resulting in a second-place finish for the league's MVP. But it was also a slog, which Manning now publicly acknowledges. By the end of the year, his arm was tired. He stopped doing his famous route tree before games, putting himself on a pitch count. In the playoffs, the Ravens dared him to throw more than 15 yards, and after losing to Baltimore in double overtime, he realized he needed to stop throwing. "He was more willing to rest his arm," Cutcliffe says.

Manning spent the offseason working on his lower body and core, strengthening his arm by strengthening his legs. Still, working within the confines of his new self is a process, learning to chase mental perfection while letting go of physical perfection, the way Jordan did when he developed his fadeaway. "When you have an injury and you have some things that aren't going to be quite the same," Manning says, "you try to be as strong as you possibly can in the areas that aren't affected."

Two areas weren't affected: his mind and his will.

"WHAT'S THE ANGRIEST you've ever seen Peyton?" I ask Broncos receiver Andre "Bubba" Caldwell at his locker.

"Today's practice," he says with resignation.

Caldwell had run the wrong route, misread something. Bubba knows that Manning won't trust him on Sunday if he doesn't trust him during the week. Manning lobbed a few F-bombs his way. But that's not what hurt, because as running back Ronnie Hillman says, Manning tends to "say a few f- and move on." No, what really hurt was when Manning told the next receiver up, "Do 100 percent the opposite of what Bubba just did."

It's not easy being one of Manning's receivers. Dealing with him throughout the week can be tougher than the game on Sunday. During walk-throughs, he sometimes orders the scout-team defense to show a few wrinkles, just to see how his receivers react. "Get in your playbook" is Manning's weeklong mantra.

That night Caldwell got in his playbook. The next day he ran the right route, and a curious thing happened: Manning came back to him. Yes, he's more demanding now than ever, but he's also more patient. Maybe it's the injury. Maybe it's being a parent to twin toddlers. Maybe it's age. He admits that he takes time to soak in the little things now. Like the plane rides. After the Broncos beat the Cowboys in that wild 51-48 October shootout, Manning sat on the team charter as it took off and looked around. No players were wearing seat belts. Everybody was on a cellphone. He laughed to himself. "When the pilot says we can't take off when those things are happening," Manning says now, "he's lying, because we do it."

Maybe Manning has more patience with his teammates because his teammates need to have more patience with him. He endures moments when something is failing him physically, and he needs everyone to stay with him until he figures it out. That's exactly what happened in the third quarter against the Colts on Oct. 20. Down 33-14, Manning didn't just seem mortal: He looked old. Two sprained ankles and an unrelenting pass rush left him unable to set his feet. Passes that Manning once hit in his sleep were now fluttering to slow deaths.