LeBron James showed us why we spend our hard-earned money to fill stadiums, waste countless hours shouting at televisions and invest so much emotionally in numbers on scoreboards. He reminded us why we love sports.

With every purposeful stroke Thursday night in his museum-worthy masterpiece against the Boston Celtics, James made the answer clear: the opportunity to witness greatness. The NBA’s most skilled player satisfied our craving during a video game-like 45-point, 15-rebound, five-assist performance for the visiting Miami Heat, which staved off elimination with a 98-79 victory in Game 6 of the Eastern Conference finals. The decisive Game 7 is Saturday night in Miami.

Facing another summer’s worth of questions about his failure in the postseason, James delivered a preemptive, in-your-face response to all the talking heads and Twitter haters eager to watch him fall again. James not only delivered while shouldering the Heat’s burdensome, self-stated championship expectations, he attacked the challenge with a level of ferocity and flair unseen since Michael Jordan was establishing his second-to-none legacy.

James missed only seven of 26 field goal attempts despite the Celtics’ best efforts to stop him, or at least slow his thoroughbred-like stride from the opening tip-off. He played all but three minutes — including every one in a 30-point first half.

This wasn’t merely a great game, of which James has had many. It was James at his historic best: He became the first player since Wilt Chamberlain in 1964 to produce at least 45 points, 15 rebounds and five assists in a playoff game (Chamberlain’s way-back stat line was 50, 15 and six). When only you and the Big Dipper have accomplished a feat in the past 48 years of NBA postseason history, you’ve done something spectacular.

A box score wasn’t needed, however, to measure James’s series-changing impact. Simply glancing at the demoralized Celtics or hearing the thud of four-leaf clovers in Boston’s eerily quiet TD Garden told the story. The synergy of James’s Hall-of-Fame talent and indomitable will lifted the Heat.

And that’s exactly what elite athletes are supposed to do. It’s what the ticket-buying, television-watching public expects.

We wanted Reggie Jackson to hit three home runs in a World Series-clinching victory. We would have felt cheated if Jordan hadn’t made the game-winning shot as the clock wound down in a close-out NBA Finals game. We had edge-of-our-seat excitement whenever Joe Montana entered a huddle late in the fourth quarter and Bears or Lions were blocking his path.

For sports fans, it’s about living vicariously through the best who have ever played. From the I-can’t-believe-I-just-saw-that present to the what-wonderful-memories-we-have past, our lives are enriched by the artistry of the all-time greats.

The anti-James crowd would disagree, but the NBA’s reigning most valuable player — and three-time award winner — is among them. James has earned that standing as much as the “dunce” label he’s trying to shake after past public relations missteps.

It’s true James still lacks the validation of a title. Throughout this postseason, though, he has effectively counterpunched the widely held belief that he lacks a closer’s mentality. It seems he was born with the “clutch” gene after all.

James’s scoring average (it’s a Jordanesque 34 points in this series) and field goal percentage (he’s shooting an outstanding 51.2 percent overall during the playoffs) have risen in each round.

Fellow superstar Dwyane Wade has struggled, and Chris Bosh is trying to revert to form after missing most of the playoffs because of a stomach muscle injury, so the Heat has looked to James to carry most of the water. He’s hauling it without complaint.

With Miami trailing the Indiana Pacers, 2-1, in the best-of-seven semifinals, James was sensational (he had a 40-point, 18-rebound, nine-assist outing in Game 4) as the team stormed to three consecutive victories.

We know that James was roundly ripped for joining Wade — and to a lesser extent, Bosh — in free agency after the 2009-10 season. In fleeing the Cleveland Cavaliers for the Heat, James acknowledged he wasn’t strong enough to guide a team to a title, many NBA observers said. Supposedly, James wouldn’t be the Heat’s leading man.

Reality is, the Heat is now James’s team. A shift occurred sometime this season. Since the playoffs began, the passing of the torch has been as clear as the ocean view from a South Beach high-rise condo.

James is the Heat’s focal point on offense and its tone-setter on defense. The team counts on James as much as any NBA franchise relies on one player.

Wade led the Heat to an NBA title and will always hold an important place in the hearts and minds of the team’s fans. You never forget your first love. But James is the Heat’s present and future.

Team officials likely would have taken a wrecking ball to the roster this offseason if Boston had won Thursday.

Heat President Pat Riley lured James to Miami to raise the only banner that truly matters, and Riley still may break up the group unless a Heat-inspired parade occurs near the end of the month.

The prideful Celtics will regroup for Game 7. The Heat is counting on it. James knows his work isn’t finished yet — which is good news for all of us who get to watch.

For Jason Reid’s previous columns visit washingtonpost.com/reid.