PARIS, KY (NBC) - Rain falls on the little graveyard at Claiborne Farm. The tour guide points to the chipped and worn tombstone of Gallant Fox, the only thoroughbred to win a Triple Crown and also sire a Triple Crown winner (Omaha). That, he says, will never happen again. He points out the great Nijinsky II, who came to stud here after winning the English Triple Crown in 1970, the last English Triple Crown winner.

There's the grave of Hoist The Flag, one of horse racing's sadder racing stories. He was an undefeated two-year-old champion who had won every race by several lengths. He was viewed as the sport's next superhorse. Then he suffered a terrible leg injury barely a month before the Kentucky Derby – the same leg injury that later led to Derby winner Barbaro being euthanized. Hoist The Flag had a better fate; doctors were able to save him and he was retired to Claiborne Farms to a successful and long stud career. But he never raced again.

All around is horse racing history – Bold Ruler, Johnstown, Mr. Prospector, Riva Ridge – but all eyes focus on one grave. The eyes always focus on one grave. Flowers lie by the tombstone. People surround and take photographs. No one cries today, but often people do cry – not out of sadness, exactly, but out of something deeper. This is Secretariat's grave.

The guide watches the people – he's seen this scene a hundred times before. It's always Secretariat. They ask him to take their photo by Secretariat's grave. He does. They ask him to tell stories about Secretariat. He does. They ask him questions about Secretariat. He answers patiently while standing in the rain. Secretariat's appeal never declines, never diminishes, it has been 40 years since his magical year and, still, there are always flowers on Secretariat's grave.

The guide would rather not give his name, he says he's just a guy who helps takes care of the horses. Even people at Claiborne Farm call him by nicknames. But he marvels at how Secretariat still resonates with people. He thinks he has a pretty good understanding why. It might have something to do with an aging horse he actually took care of on a different farm some 20 years ago.

That horse's name, poetically and wrongly, was Sham.

"Born in the wrong year," the guide says, a perfect five-word summation of one of the worst bits of luck in sports history. At the 1973 Kentucky Derby, in front of what was then the largest crowd ever at Churchill Downs, Sham hit his head on the starting gate and lost two teeth at the start. He then crashed into a thoroughbred named Navajo, and in the process cut his left leg. Even after that, Sham went on to run the Kentucky Derby faster than any horse had ever run before.

Yes, Sham's time of 1:59.8 would have been the Derby record. A run for the ages. Sham was eight lengths clear of the field when he finished – that is, of course, the field except for Secretariat. Born in the wrong year. Secretariat pulled even with Sham as they entered the stretch, and they ran together for three strides, four … and then everyone saw the difference between what is great and what is something beyond. Secretariat pulled away from Sham. Secretariat won by 2 1/2 lengths. His time, 1:59.4 is still the Kentucky Derby record.

Then, the Preakness, and this race was a bit different. Only six horses raced at Pimlico in 1973 - already Secretariat was scaring off competitors - and Secretariat was last as the horses headed into the first turn. Then Secretariat made one of the most famous moves in horse racing history, going from last to first in what seemed like an instant. It was such an extraordinary move that in the movie "Secretariat," the filmmakers wisely decided to show actual footage of that race rather than try to recreate it. There is no recreating that move.

But what people might not remember is that when Secretariat made the move, Sham also came alive. He made his own move; he went after Secretariat. Sham raced by the field, and for a while, he gained on Secretariat. As they headed into the stretch, it seemed like Sham might just catch Secretariat; he had pulled to within a length. But, once again, there was that difference between great and what is indescribable. Secretariat maintained the lead and then pulled away. The timing mechanisms at the track had malfunctioned so it would be decades before people would know for sure that Secretariat had broken the time record for the Preakness Stakes, another record that still stands.

Sham finished second – again, eight full lengths ahead of everyone else.

But, none of these races – I believe – are the reason that Secretariat is still beloved forty years later. There have been many great racehorses that have run magnificent times. Heck, just after Secretariat, came Seattle Slew, who won the Triple Crown and did what even Secretariat could not do – Seattle Slew never lost a race. And then came Affirmed and Alydar, horse racing's greatest rivalry, horse racing's Ali-Frazier or Chrissie-Martina, with Affirmed winning the Triple Crown by the slightest of margins. Yes, there have been other amazing thoroughbreds and amazing stories.

No, what separates Secretariat happened forty years ago Sunday. And, once more, Sham played his part.

Everyone knew Secretariat would win the Belmont Stakes. There were only five horses in the race – and Secretariat was a 1-to-10 favorite. That meant you could bet a dollar on Secretariat to win a dime. Many people who were betting on Secretariat were not even interested in that dime; Secretariat was already such a legend that people were mostly placing two-dollar bets so they could frame the ticket.

But Sham's trainer, Pancho Martin, believed in his horse. He told his jockey, Laffit Pincay Jr., to keep Sham with Secretariat. Stay with him. Pincay followed orders, and he sent Sham out with Secretariat. They were side by side entering the first turn. They were running faster than two horses had ever run before at such a long race. They were moving faster than they had at the Kentucky Derby, faster than the Preakness. It was what horse racing analysts like to call a suicidal pace.

And they ran together, side by side, through the first turn, into the backstretch, they ran together and they were six, then eight, then 10 lengths ahead of every other horse. Sham had his neck out front for a bit, then Secretariat pulled even. Even the announcer, Chic Anderson, could not help but say, "It's almost like a match race."

And then, slowly at first, Secretariat began to pull ahead. He had a half-length, then a length, and you could see something happen. Nobody knows what these thoroughbreds think while racing. They might understand what's going on, they might not understand it at all. But somewhere on the backstretch at the Belmont, Sham ran out. And Secretariat, already running faster than any racehorse ever had and perhaps ever would, started to really run.

The end is well known. Secretariat pulled away and pulled away – "He is moving like a tremendous machine!" Chic Anderson shouted. Secretariat did not just win the race by 31 lengths, one-sixteenth of a mile. Secretariat did not just smash the Belmont Stakes time record by almost three seconds – a time so fast that, as the legendary columnist wrote, he would have beaten the previous record holder Gallant Man by 13 lengths.

No, even more, Secretariat left an image so indelible, so electrifying, that it remains timeless. Even forty years later, Secretariat seems as new and thrilling as he did the moment near the finish line, when his jockey Ron Turcotte looked back just to see how far back the other horses ran.

And Sham? He was broken. He had run that first mile in a time about as fast as his Kentucky Derby, he had gone stride for stride with the great Secretariat for as long as he could, and then he had nothing left to give. He had played his part. Laffit Pincay, understanding the truth, eased off Sham and let the other horses pass. In his last race, Sham finished last.

"He was a good ol' horse," the guide says of Sham as we stand in the rain, but he knows that people are looking at Secretariat's grave and not really listening.