Reggie Jackson was holding court in the bright Northern California sunshine, engaging a small cadre of newspaper and radio folks around the batting cage at Oakland-Alameda County Coliseum. It was Oct. 21, 1973, and in a few hours Jackson’s Oakland A’s would host the Mets in Game 7 of the World Series.

“Game 7, do or die,” Jackson said, smiling. “I don’t know who’s going to win. But I know this: Someone on one of these teams is going to do something that’ll be remembered forever — good or bad. That’s Game 7.”

As was Reggie’s wont, he would volunteer his own services for that duty, hitting a two-run home run and leaping onto home plate with both spikes for good measure, helping the A’s to a 5-2 win and a second-straight championship. It was good enough to earn him MVP of the Series even if he only hit .240 in it.

That’s the magic of Game 7. That’s the wonder. That’s what the Rangers have before them Monday night at PNC Arena in Raleigh, N.C., when they’ll try to spoil the Hurricanes’ unblemished home playoff record, when they’ll hope to squeeze into the Eastern Conference finals — halfway to the Cup.

And when Someone will do Something that’ll be remembered forever.

“Nothing is better than a Game 7,” Walt Frazier said a few years ago, near the anniversary of one of the truly epic Game 7s ever. “But nothing is quite as terrifying, either.”

Clyde, of course, delivered the coup de grace of Game 7 performances, going for 36 points and 19 assists (plus seven rebounds and four steals) when the Knicks knocked off the Lakers in 1970 for the franchise’s first-ever title. That truly has lasted forever in the minds and hearts of Knicks fans.

And the fact that it was a Game 7 — all the money on the table, winner take all — makes it so. If he’d done that in Game 1? Or even in Game 6, in LA, wrapping the series up a game early? He’d still be the toast of the town, sure. Just not to the extent doing all of that in a Game 7 allows.

Mark Messier delivered one of the most epic moments in Rangers history in 1994, first guaranteeing victory over the Devils in Game 6 of the Eastern finals, then securing that pledge with a natural hat trick. It remains one of the astonishing accomplishments in the whole history of New York sports.

Still: When Rangers fans use shorthand to talk about those ’94 Cup champs, what do they say?

“MATTEAU! MATTEAU!! MATTEAU!!!”

It’s Game 7. It’s forever. Endy Chavez could have caught that ball against the Cardinals in the 2006 NLCS with his shoes in Game 3 and it wouldn’t have been as well remembered as the catch he did make in that Game 7. And similarly — proof that it isn’t always balloons and teddy bears — one of the truly great careers any Met everyday player has ever compiled — the one belonging to Carlos Beltran — is, in the eyes of many Mets fans, canceled out to large extent because he didn’t swing at that Adam Wainwright nose-to-knees curveball a few innings later.

This is the 77th time a New York-area team will partake in a Game 7, a rich tapestry that dates to 1912 and the old New York baseball Giants (who, technically won a best-of-seven in Game 8, thanks to a tie) and the roster of unforgettable images and instant heroes is deep and eternal.

Johnny Podres and Aaron Boone, bookend unlikely heroes, had their Game 7 moments. For Yankees fans of a certain age, the footage of Yogi Berra slowly jogging away from the left-field wall after Bill Mazeroski’s blast remains a source of sporting trauma, as does Luis Gonzalez’s bleeder over the infield. Nets fans lamented for months that Kevin Durant’s shoes weren’t a half-size smaller when his jumper at the end of Game 7 last year was ruled a tying 2 instead of a winning 3.

The Rangers are only here because Artemi Panarin scored in overtime 15 days ago, securing a Game 7 win over Pittsburgh in the last round. They know Game 7. They’ve been to Game 7. They already survived Game 7. Do so again, get halfway to the Cup, we’ll get a sporting buzz brewing in this city we haven’t heard in way too long.

And bank on it:

Someone will do something. And it will last forever.