No one dies at 51 anymore. So we tell ourselves. But James Gandolfini somehow did.

Tony Soprano’s heavy breathing was part of the astonishing reality of “The Sopranos.” What we told ourselves is that it was the sound of a big, overweight, hopelessly urban man who moved to the suburbs without fully investigating what all those pollens might do to him. But we know now that it was Gandolfini we were always hearing, not Tony Soprano.

So overpoweringly real was the show to us – one of the greatest in TV history – that most of us lacked all ability to think about Gandolfini the actor. All we could think about was a mob boss like no other – a middle-class suburbanite in a terry-cloth bathrobe anyone might see going outside to get his morning paper in the driveway. You could meet this guy at the deli counter at Wegmans or in a coffee shop.

The major difference is that this suburban neighbor was a mob boss who whacked people, even when he took his daughter to Maine on her college trip. He was a guy who had them whacked and who never expressed more joy than when he and his nephew Christopher could personally heist a truck.

It may have been writer-producer David Chase’s genius that made “The Sopranos.” But it was Gandolfini who made the show a turning point in American television. It’s literally true that television after “The Sopranos” will never be quite the same again. He was, like Jean Stapleton, so good at playing one character that the one character he played was as alive as our own next door neighbors.

Gandolfini, the actor, made a lot of movies after his debut as Tony. He was always capable. But we could never quite believe any of those characters. He could never be them. Just as Stapleton was always Edith Bunker, the most lovable character in TV history, he was always Tony Soprano, an evil man but one so vividly like the rest of us that he taught us more about being human than our own lives usually did.

And now, for entirely different reasons, James Gandolfini is dead far too young.

In that one way, he’s just like a mob boss whose lights went out instantly over an ordinary dinner out with his family.

An amazing actor. He and his show changed what Americans knew – and what Americans thought they knew.