Julius "Dr. J' Erving celebrating his number retired and raised...

Julius "Dr. J' Erving celebrating his number retired and raised at the Nassau Coliseum during half time of game between the LI Nets and the Fort Wayne Mad Ants on Sat. Nov. 4, 2017 Credit: Errol Anderson

It was 30 years ago that the Nets officially retired Julius Erving’s No. 32. At the time, he was shaken and moved to tears. Then in his final season as a player with the 76ers, he thought back on those three wonderful years on Long Island and said, “A tree without roots cannot stand. Everything needs to have roots.”

Which is what made Saturday night hit you right here, in the heart. This time he was returning to his roots, and by means of that jersey in the rafters at Nassau Coliseum, he always will be there.

No offense to all of the other places at which he has been honored — including the Basketball Hall of Fame in Springfield, Massachusetts, or East Rutherford, New Jersey, where the peripatetic Nets first honored him in 1987 — but Long Island is where he is from. It is where he was born, where he grew up, where he became Dr. J. It is perfect that a reminder of him is here to stay.

“They say you can always go home,” he said. “This clearly is home.

“I was born right up the road in the old Meadowbrook Hospital,” he said, adding that he went to elementary and junior high in Hempstead and high school in Roosevelt before he changed the sport of basketball right on Hempstead Turnpike with the New York Nets of the American Basketball Association.

A person could argue that there was something undeservedly low-key about the setting Saturday night: a promotion at halftime of a minor-league game, the debut of the Long Island Nets. But it was good enough for him to be here, so it is good enough for the rest of us.

“It’s hallowed ground in terms of the success the Nets had, the success the Islanders had,” said the man who used to soar in that very building (now spruced up and officially renamed NYCB Live) while carrying an entire league on his shoulders.

The Long Island Nets showed video (some in black and white) of Erving leading the Nets to the 1974 and 1976 ABA titles, of Erving taking off from the foul line to win the slam dunk contest at the 1976 ABA All-Star Game.

He kept that league alive. He is the single greatest reason the Nets, Pacers, Nuggets and Spurs survived to join the older league. Much of what the NBA has become has its roots in Erving’s Nets era. “The ABA is embedded in the NBA,” he said Saturday night.

He is amazed at how the ABA’s three-point shot has become the dominant factor in basketball at all levels. Those of us who watched it all develop are amazed at how the slam dunk contest, which debuted with the ABA and was popularized by the man who won it, has become such a “thing.” It has led to skills contests at All-Star Games at all the other sports.

Fact is, Dr. J of the Nets was more than a good forward who could dunk. He was and is a game-changer.

It was a crying shame that there was a contract dispute with Nets owner Roy Boe, who, strapped for cash because of indemnity payments to the Knicks (on top of the Islanders’ indemnity payments to the Rangers), sold him. What a treat it would have been for Long Island to see him become an NBA fixture right here.

So it goes. He still is from here and always will be. He was honored to present an award to Don Ryan, his first mentor and longtime youth league coach whom Erving called “the most dedicated servant I’ve ever seen.’’

I’ll never forget hearing Erving welcome fellow Long Islander (and fellow No. 32) Jim Brown to a celebrity golf tournament out east by saying, “Welcome home.” We can say the same for his red, white and blue Nets jersey, which hangs alongside the two ABA championship banners.

Long may they live. As Erving said, sitting near his old home court, “Time fleets by very quickly, but memories seem to be forever.”

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