When Downing, a cunning left-hander with the Los Angeles Dodgers in the latter stages of his career, delivered the fourth-inning pitch that the bravest of Braves launched into the Atlanta night, the world became a different place.
A black man from the Deep South had eclipsed Babe Ruth as the all-time home run king, arriving at the summit with a dignity and style that could not possibly be missed. That meant as much as the numbers 715, and, later, 755 would in the grand scheme.
Henry Louis Aaron -- the very first name in the Baseball Encyclopedia -- was the undisputed heavyweight champion of Major League Baseball.
To have been there, in the flesh, is something you carry around for life. A moment or two of reverie recalling the wonder of it all, has brightened many a dreary day.
There, in the mind's eye, is the purposeful Aaron, making his familiar stroll to the plate, stopping to calmly place his helmet on his head and ease into the batter's box before training his sights on the mound.
There stands Downing, one of the game's premier craftsmen. After a youth spent with a bazooka serving as a left arm, Ace had evolved into a pitcher's pitcher, his knowledge and command of the art serving him long after his mid-90s heater had become a memory.
Downing would come at Aaron with his best stuff -- that much you knew. Aaron would have to reach this milestone by tapping into that reservoir of knowledge and awareness. You don't hit 700-plus home runs on talent alone.
When the stunning moment arrived, the baseball rising in an arc toward the fence in left-center, there was a stillness in Atlanta-Fulton County Stadium -- the calm before the storm.
Then came an eruption, pandemonium. Bill Buckner, the young Dodgers' left fielder, was bouncing back off the fence, unable to retrieve the valuable baseball. It fell to Braves reliever Tom House, who set off in a dead sprint for home plate to present it to the new home-run king.
To sit there and absorb it all -- a 25-year-old baseball writer wet behind the ears, making his first road trip as a full-time Dodgers beat reporter -- was overwhelming.
It would be accurate to report that the eyes got misty as Aaron circled the bases, encountering to his amazement a pair of uninvited guests, young men who'd bolted out of the stands to run with Hank.
Their indiscretion notwithstanding, it was a fine and delirious sort of madness enveloping the ballpark and 53,775 fans.
It is not often you're allowed to sit in on history, and it's a good idea to appreciate how lucky you are.
The rest of that night is a blur.
Watching fans leave in droves as play resumed, no more than 10,000 still around when the Braves wrapped up their victory ... Trying to pay attention to the rest of the game from the press box, hands pounding away on a typewriter, desperately searching for the right words for the occasion ... A postgame interview session with Aaron, then dashing off to gather quotes from anybody else offering insights, including the exciting young Braves star, Dusty Baker, who so admired Hank.
The young reporter had spent time with Downing in the visitors' clubhouse before the game for background material, exploring the pitcher's thoughts with George Plimpton, the celebrity author. The reporter was enthralled by Downing's calm, easy manner, his steely resolve. And then Al excused himself to go take a nap. Seriously.
There wasn't much sleep for the young reporter that night after the work was done.
This was a night for celebration throughout Hotlanta.
Late the next afternoon, in the visitors' dugout, the reporter and Downing were talking when Aaron came over to shake hands and have a word with his long-time rival. It was the kind of quiet moment between two people that could never happen today.
There was something extraordinary in that moment, feeling the mutual respect shared by Aaron and Downing, knowing they'd be linked forever and that this was a scene to frame in the mind.
The young baseball writer then did a highly unprofessional thing. He politely asked Aaron, before the great man walked away, if he'd mind signing his scoresheet from the previous night.
Without a word, he took the scorebook in his large hands and carefully wrote, "My best, Hank Aaron."
That's something the journalist never would consider doing again. Properly so.
In the 33 years since Hank took Al deep, forever uniting them, nothing has quite measured up to the magic of that April night in 1974.