For those who have never witnessed a man become a legend before, it takes less than 20 seconds. Or does it?
Put it this way: Usain Bolt was not a legend on Wednesday but he was on Thursday, so it must happen overnight. Well, maybe not.
Bolt would never have been in a position to become a "legend" had he not set the world back on its heels four years ago in Beijing by running the quickest and most astonishingly beautiful 100 metres ever seen.
Ditto if he hadn't followed that up by running the most amazing 200 metres ever seen.
Ditto if he hadn't done an encore four years later in London by winning the 100 metres again, incidentally in a time better than he ran in 2008.
So here he was, on the brink of athletic deity status, which he duly confirmed, as the whole world knew he would, with a repeat victory in the 200 metres.
Bolt ran a fabulously quick first 100, then appeared to be in danger of being caught by his young training partner Yohan Blake in the home straight before kicking away again.
But he still couldn't help himself from pulling up slightly just before the finishing line, crossing with a finger to his lips as if to hush the jam-packed crowd in London's Olympic stadium.
He clocked 19.32 seconds, just outside his Beijing time, but he got home by just 12 hundredths of a second, which is taking showmanship way across the line into brinkmanship.
And how did Bolt celebrate? By doing push-ups on the track, of course.
He and his teammates made it a Jamaican clean sweep, 1-2-3, with Warren Weir getting bronze. (Keep that tucked away to win a beer some time).
He thus became the only man ever to successfully defend both the 100m and 200m Olympic titles.
That met his own definition of what it takes to be called a "living legend".
Most people had probably already accorded him that status. I for one would have been tempted to grant it on the basis of that Beijing bolt alone. It remains one of the most extraordinary feats of athleticism I have ever seen. But at least everyone can now agree.
Some athletes are brutally effective but run ugly. It hardly seems fair that Bolt runs so quickly and with such grace, style and economy of movement. It makes him a gift to sprinting in the way that Mozart was a gift to music.
He is so aesthetically pleasing that your eyes would probably be drawn to him if he was running last.
The frightening thing for his opponents is that the 200m is his preferred race.
If he had blown them away again in the 100m, what chance did they stand over the longer distance, when he really has the chance to wind up after his traditionally slow emergence from the blocks?
For anyone who likes to see something done wonderfully well - dare one say as perfectly as seems humanly possible? - it is a special treat to have been born at the right time to see him pass by, even at such speed. Especially at such speed.