The age of Usain Bolt is nearly over and so the present must be cherished.
Bolt, the fastest man in history, one of the greatest sportsmen to have ever lived, will run his last race at the World Athletics Championships in London.
He will retire having left his mark on history: the first man to win three 100m Olympic titles, the world record holder in both the 100m and 200m, a winner of 23 major gold medals.
His legacy is assured. No man has run with such speed or enjoyed such longevity. The 30-year-old's extraordinary achievements will be looked back upon with wonder by future generations.
They will watch replays of the young Bolt of Beijing, hushing the crowd on the starting blocks before bang... history -- his arms raised, thumping his chest, clocking a barely believable 9.69 seconds to shatter the 100m world record.
The 21-year-old's speed was jaw-dropping, the other eight men in a distinguished field left trailing in his wake.
They were in a different race and this 6ft 5in newcomer was from another planet.
Two more gold medals followed on the Chinese capital's lightning-quick track, his 2008 coronation as sprint king complete.
Hearts and imaginations were captured and he has been loved ever since.
The irreplaceable joker-in-chief
There have been so many glorious moments.
Berlin in 2009, when the Jamaican reduced his 100m and 200m world records further; London 2012 when all three of his Olympic sprint titles were retained.
Back to Beijing in 2015, older, ailing, but managing to fend off the challenge of twice-banned Justin Gatlin to retain his grip on 100m and 200m world titles.
Then there was Rio last summer, his Olympic farewell ending in further triumph.
Those who will live in a Bolt-less sporting age will wish they had been there, just as we all want to be inside London's Olympic Stadium on Saturday when the history-maker lines up in the 100m final for his last competitive individual race.
The 4x100m relay on August 12 is likely to be his grand encore. The final act of this gilded athletic tale.
There is little point asking who will take over once he is gone. No-one can clown around on the start line and execute excellence like track and field's joker-in-chief.
As the eight-time Olympic champion himself said this week, it will take more than one athlete to fill his vibrant void.
Savor him now because Bolt is irreplaceable.
"It's a simple formula that doesn't actually work," says Michael Johnson, whose 200m world record was thought unbreakable until Bolt broke it ... twice.
We asked him how his sport will cope without its showman.
"The idea that you have an athlete who's the best there's ever been in the sport, who just happens to have an electric personality as well," explains Johnson, a four-time Olympic gold medalist, "you're not going to replace that.
"That's not going to come around again. It would be ridiculous to look for it and, I think, the sport has made a mistake by relying on that for the last eight years because he was never going to last forever."
Becoming a legend
Hoping that the show would go on and on is perhaps forgivable. It is easy to forget that even the seemingly superhuman age, just like the rest of us, no matter how effortless and enjoyable they make winning seem.
A showman supreme, a magnetic personality, he has been likened to Muhammad Ali, though he has stayed away from politics.
He has continued to compete because he knew only sustained success would see him ranked alongside the three-time heavyweight champion and Pele, regarded as the greatest footballer of all time.
He wanted to be "among the greatest," he said before going on to achieve an unprecedented "triple-triple" of Olympic sprint golds in Rio, though he has lost the 4x100m relay gold he won in Beijing as a result of team-mate Nesta Carter's positive doping test.
"I am a legend," Bolt has said a number of times, after winning three golds in London, and again in Rio.
It would be braggadocio from anyone else but, as he himself has explained, he has proved himself to be the best for nearly a decade.
"I feel that if you have done something, it is not bragging," he has said.
But even Ali, like most in life, had to comeback from lows. It added to his legend. Bolt, however, has excelled at major championships no matter what his form or fitness. His only failure was a false start in the 2011 World Championships 100m final.
Yes, he has slowed over the years and the frequency of injuries have increased. At times, the country boy who began racing to buy his mother a washing machine has also struggled for motivation after achieving more than he ever dreamed.
But even Bolt beyond his peak has always managed to be better than the rest.
"He's just a phenomenally talented athlete," says Johnson.
"He's absolutely been tested. I don't think that you could discount anything that he's done over the years. Some of the fastest times in the 100m and 200m have come about during his career."
'You have blessed us with Usain Bolt'
The sprint freak from a remote Jamaican village has already said his goodbyes to his own; a five-hour farewell in the national stadium in Kingston, a celebration which started with prayers from an ordained minister.
"We thank you God, for you have truly been good to Jamaica," it began. "You have blessed us with doctor, the honorable Usain St Leo Bolt, the embodiment of sportsmanship, who remind us of the gumption and indomitable spirit of the Jamaican people."
Thirty-five thousand people watched their most famous son run his 84th and last race on home soil. Bolt, so those on the inside say, would have preferred for that to have been his farewell.
He is most comfortable at home, living as ordinary a life as a millionaire superstar can. He trains in a public gym, dances in nightclubs. There is no need for private security.
It is when he steps onto foreign soil that people become agog by his presence, which means life on the road is mostly spent in hotels.
"In Jamaica you take it for granted that you can see him every day," says Colin Reid, a photographer who has followed Bolt's career with the Jamaican Observer.
"In the international fraternity, they're awestruck. But he's just like one of us. He lives in Kingston. He's approachable, he's amiable, I see him around a lot."
What you see is what you get, says Reid, something Bolt has also repeated in numerous reports. He enjoys partying, he is still the boy a teacher once described as being full of "tricks and stories."
Bolt the thinker, the intellectual
Hidden behind the tomfoolery on the track, however, is a thoughtfulness, a keen athletics brain and an intense competitive streak.
He is a smiling assassin. His desire to be the best is such that he no longer plays Call of Duty as he cannot cope with not being as good as he used to be.
"He's much different when he's in a much closer setting," says Johnson.
"Unfortunately, I don't think the world has been able to see that he is very thoughtful, highly intellectual about athletics, about sprinting.
"Most people think that he goes out there and that it's easy and he doesn't really care if he wins or loses, that he's just having fun."
Bolt has said he allowed a film crew to follow him in the year leading up to Rio for the movie "I Am Bolt" so people could see how hard he worked; vomit-inducing track sessions, suffering in the gym, early-morning wake-up calls.
Ed Moses, a two-time Olympic champion who dominated the 400m hurdles in a 122-race unbeaten decade, calls Bolt a mathematician, though when later asked his agent Ricky Simms admits he has never heard his client described as such.
"He's an intellectual guy," says Moses.
"He's thought a lot about what it's going to take to get him through the first 40m. He had the tools and resources to put it together and that's why he's great."
Unlike many of history's great talents, Bolt has been appreciated in his own time. For nearly a decade he has radiated in a sport darkened by doping.
Nine of the 30 fastest 100m times, including the top four, are Bolt's. The other 21 marks on that list have been run by athletes who have, at some point, tested positive for doping.
Questions have been raised about Bolt, especially when he first emerged in Beijing. After all, athletes as tall as him are not supposed to run that fast, but the man himself is not bothered by such talk.
He is different, a speedster whose long levers allow him to cover the 100m in just 41 strides when others need a few steps more and a little more time.
And so, in under 30 seconds, or 132 steps, Bolt's career will be over. He will be out of sight, as he has been to his competitors for most of his career.
There will be no fooling around, no celebratory "To Da World," no electrifying nights under the floodlights.
It will never be the same again.