A bell hangs above the door of Holsten’s ice cream parlour in New Jersey, and every time the door opens, the bell rings. But we’ll get to that.

First, we have to go back to 1963, and an episode of The Twilight Zone called “The Bard.” The show’s creator, Rod Serling, one of the greatest talents television has ever known, wrote it himself, probably as a joke, but, equally, probably not.

It’s about a hack writer struggling to come up with a script for a TV pilot. Somehow, through cack-handed black magic, he manages to summon William Shakespeare into the present, and talks him into ghosting the script for him. Shakespeare crafts something brilliant; then, he watches in horror as the TV network and its advertising sponsors begin to meddle, revise and censor it out of all recognition.

Why am I going on about an old episode of The Twilight Zone? I’m not sure. Except that, when Tony Soprano, face filling the screen like a dead moon in the sleeping close-up that has become the programme’s signature shot, snorts himself awake at the start of the final episode of The Sopranos to remember that his terminal little war with Phil Leotardo is still going on, and that he’s stilled holed up with what’s left of his crew in an anonymous safe house, rifle by his bedside, he discovers that episode flickering on the TV as he wanders downstairs.

The last great art work of the twentieth century– it was a TV show, but also a movie, a novel, a Guernica, a sprawling, strange, sad silly symphony and a loony tune – ends this week, or should I say, it ends again. The chances are you’ve already seen the final episode, which went out in the US in June, or at least heard how it ends. But just maybe you haven’t, and it would be a hideous thing to spoil it.

So, instead, there’s that opening, and “The Bard.” (There’s a cat in the opening sequence too, and this cat hangs around – but to talk about that would get too spooky.) It goes without saying that David Chase, the creator of The Sopranos, chose to put “The Bard” in there for a reason. Probably, in this, his kiss-off to television, where nothing really changes, as a joke. But, equally, probably not.

What is certain is that by now, nothing is there by chance in The Sopranos, not even if it is there to spark a feeling of chance, that curious, dreamy sensation you get when your awareness picks up stray random data and makes it collide – walking down a street, you hear a song from a glinting window, notice a figure turning a corner out of sight – so unnameable associations start flashing between your synapses.

In The Sopranos’ densely rich tapestry, some things are there for reasons that seem clear enough. (A tour bus passes in the final episode, and we hear the guide speaking: “This is New York’s famous Little Italy. It once covered over forty square blocks, but has now been reduced to one row of shops and cafés.”) Just as often, though, moments and images are enigmatic, stubbornly poetic. It is this that has led to one of the most persistent complaints about the most recent series: that the programme has become too slow, too unfocused. To which I can only ask: too slow for what?

One of the most revolutionary things about The Sopranos has been how it has embraced and exploited the elements unique to television – the opportunity of intimacy and time, the potential to tell a very long story and go deep, time enough to watch an old man slide into dementia and realise that he’s really gone – and opened it out without becoming soap, becoming instead a kind of dub TV, all space and delayed echo.

Ultimately, as the inclusion of “The Bard” underlines, and as the ending I’m not going to talk about stresses so forcefully you actually feel a physical and psychic shock, one of the things Chase’s programme has been about has been watching television – in the same the way that, 50 years ago, one of the things Hitchcock’s Vertigo was about was watching movies.

The Twilight Zone is an old programme that can still feel more modern than most programmes being made today. The Sopranos is the most modernist TV programme ever made, and yet it feels so much older than the other programmes around it. Its men – Christopher, Paulie Walnuts, Silvio, Junior, Pussy, Bobby Bacala, poor Artie, Johnny Sack, Richie Aprile, Ralphie, Patsy – had faces that wouldn’t have looked out of place in Bilko’s barracks. Its women – Carmela, Dr Melfi, Adriana – could have argued with Barbara Stanwyck.

Chase, who was born in 1945, grew up on Silver Age television. I once heard him give a talk in which he stressed the importance of watching The Million Dollar Movie, a slot on a New York TV station in which they would play the same film five nights a week. This was where he first encountered White Heat, the movie with Jimmy Cagney as a mother-fixated gangster that, along with The Godfather and Goodfellas, became part of The Sopranos’s Holy Book.

Nostalgia has been another great theme of the programme, but in Tony’s case, numbed by the sensory overload of the present but desperate to feel, it is a bankrupt nostalgia, nostalgia for a past he was too young to know, and that probably never existed.

It’s there in the final scene, in the calm, threat-filled air in Holsten’s ice-cream parlour. Holsten’s exists. It’s a real place, you can go there. But, as filmed in the final episode of The Sopranos, it has the dreamlike sense of being a bubble from the past, floated in somehow from the early 1960s, simultaneously then and now at once.

The bell above the door rings. Ask not for whom the bell tolls. It tolls for we. Like Paulie says: “In the midst of death, we are in life, heh? Or is it the other way round? Either version, you’re halfway up the ass.”

A version of this review ran in The Sunday Herald, October 28th, 2007