Do you remember where you were when Jonah Lomu trampled over Mike Catt in the 1995 Rugby World Cup semi-final?
Do you remember how he gathered the ball almost with his back to play, and seemed to amble down the left wing, with the pace of a sprinter but the momentum of a juggernaut, keeping his balance as Will Carling attempted a tap-tackle, before spring-boarding off Catt's chest to seal the most iconic try of his career?
Do you remember that he was 20 years old back then, a freak of nature with the height of a lock forward, the bulk of a prop and the speed of a leopard, and do you remember how he'd been an open secret all World Cup long … quietly devastating in the group stages, but knowingly holding back an extra gear for the tournament's sharp end?
And do you remember thinking, "Jesus Christ, I've never seen anything like this in my life"?
This is how it has felt to watch Jofra Archer in the past 24 hours. This is how it has felt to watch him return to the scene of the greatest triumph of most cricketers' careers, and make his Super Over heroics in the World Cup final seem like a prologue to his truest calling.
He said before the match that red-ball cricket was the format that suited him best, and we coughed politely, thinking: "Mate, you've conquered the world at the age of 24 … we've seen it all already, surely"? For the second day running … well, we've seen it all now, surely.
Except … we clearly haven't. Because, by the standards of any ordinary debutant performance, Archer's final match figures of 5 for 91 in 44 overs would be classed as "promising";, even "very promising", but not much more than that.
"The boy's got an exciting future," one might even be moved to write, and certainly, Tim Paine, Australia's captain wasn't about to get swept up in the moment. "Guys have been around bowling 145, 150ks for a long time," he said. "It's a challenge but that's why we're playing Test cricket."
And there's no way that a bowler who had stampeded down the slope at the Pavilion End to such tremulous effect should have been able to amend his angles so effortlessly from the Nursery End, in only his second first-class contest at the ground, remember, and unleash another reign of terror that briefly threatened to tear this contest wide open again on the final day.
It was several long minutes of examination and speculation about the 'concussion sub's concussion sub' before Labuschagne was cleared to continue his steadfast innings
In the first innings, Archer had been a touch too short with the new ball, not quite challenging the bat in the manner that Chris Woakes might have done, and there was a school of thought, shared most notably by a fellow firebrand, Mitchell Johnson on TMS, that Joe Root would have been better off trusting the precious new ball to a man who averaged 9.75 with the ball on this ground and who combined with Stuart Broad right here last month to rout Ireland for 38 inside 16 overs.
But there was a different dynamic at play in the denouement to this contest - because England clearly felt that the pursuit of an unlikely victory was inextricably linked to the crushing of Australia's soul.
Enter Archer, and exit David Warner for his fourth single-figure score in a row, caught poking on the top of off every bit as expertly as Woakes, or James Anderson, or any of the great Lord's slope-exploiters might have done in the past.
But with Australia's one true route to an improbable run-chase gone, and with Marnus Labuschagne - making history as Test cricket's first concussion replacement - soon in Archer's sights as Usman Khawaja fenced a flier through the keeper, Lord's ordinary rules of new-ball engagement went flying over the pavilion fence.
Labuschagne's first delivery of the Ashes didn't even register as a delivery at all, it was such a short and shatteringly quick bouncer that Jonny Bairstow did well to claw it down.
But the second … my God, the second.
Nasty, brutish, and short … just as Labuschagne's Ashes campaign briefly threatened to be, as his head recoiled like the butt of a 12-bore shotgun as another impossible-to-avoid exocet crashed into his grille.
To his credit Labuschagne watched it as well as he could, wrenching his face out of line only when the final split-second made it clear that a collision was inevitable. And though he fell to the floor he was up before you could start the count, shrugging his shoulders and puffing his chest like a nightclub brawler who still wanted some, alwight?
But it was several long minutes of examination and speculation about the "concussion sub's concussion sub" before he was cleared to continue an admirably steadfast innings that lived up to his mock-able billing as Steve Smith's like-for-like replacement. By the time of his disputed extraction at short midwicket for 59, he had carried their combined average for the series to 109.25 by posting their eighth consecutive Ashes half-century.
But that is the thing about Archer's impact on this Test. It hasn't been measurable by your everyday statistics - no more than three wickets in either innings, as well as a spell that genuinely amounted to a waste of the first new ball on Friday's truncated action.
And nor did it even lead to victory, irrespective of his late - and frankly questionable return for a final five-over burst: Joe Root, you are aware the Headingley Test starts in just four days' time, aren't you? But, neither did Lomu's World Cup campaign - New Zealand ran out of road in South Africa's glorious final, and sadly he never got a better chance. But that did not detract from the fact that an iconic awakening had been witnessed.
Ben Stokes, a gruff Kiwi-Cumbrian not given to hyperbole - especially not in the wake of his own outstanding performance in this Test match - described Archer's performance as "frightening", and there's no doubt that his impact, literal and otherwise, was as chilling as his demeanour was ice-cool.
Like Michael Holding before him (and one doesn't make that level of connection lightly), Archer's rhythmical approach seems to have a hypnotic effect on batsman who, even deep into an innings, can sometimes seem stunned at just how much heat he can generate without any apparent effort. And like Malcolm Marshall (ditto), he comes armed with a bouncer that can skid into helmets with liquid, lethal intent, and perhaps unsurprisingly has struck more of his opponents (15) since his international debut in May than any other bowler on the world game.
Is it too soon to make such comparisons? Perhaps, though sometimes you just have to make the big calls on big careers (and again, it's not as if Archer hasn't just bowled England to a World Cup win within weeks of his international debut).
And even if, for whatever reason, he ends up falling short of what might have been - and over-use seems the likeliest route to unfulfillment - it's hard to recall many fast-bowling debuts that will resonate like this one. It's been 33 years and counting since Patrick Patterson, for instance, chilled England's batsmen to the marrow with his lethal debut at Sabina Park in 1985-86. And no matter where he ended up in the pecking order, Graham Gooch, for one, will tell you to this day that that was the fastest and most frightening thing he ever faced.
Steve Smith, you suspect, may one day admit the same.
There will be challenges ahead, not least for his captain Root, who seemed in danger of playing with his new toy to destruction in turning to so often and in so many roles, to the extent that shortly after the close, Archer self-mockingly tweeted a gif of a man with a walking stick struggling to get off a sofa.
"It's something new to work with," Root said. "He makes things happen when not many others in world cricket can. He has such a unique action and way of bowling, and obviously natural pace which is always going to be in the game on any surface. So when you've got that and the skill of the other guys around it, it makes for a tasty combination."
It makes for a tasty Ashes denouement too. Even as England's unrivalled summer of cricket clicks into an autumnal hue, there's everything to play for, and one man in particular making most of those plays.