The initial response on social media was uniformly, incredulously positive - "Al Pacino is coming to Glasgow!" - closely followed by a slightly less euphoric reaction to the ticket prices: £65 for the Clyde Auditorium cheap seats, rising to a rumoured £25,000 if you fancy joining the great man on a post-show private jet to London.

Awe and shock aside, the sold-out event itself deserves analysis as an eccentric cultural occasion - an explanation not only of what An Evening With Al Pacino might be, but also what it may mean.

There is no doubting the man's status in cinema history, largely assured by an astonishing period at the start of a career which saw Pacino garner five Oscar nominations over the course of just seven films. The streak began, of course, with the first Godfather, which saw the young unknown championed by director Francis Ford Coppola and co-star Marlon Brando in the face of exceptional studio hostility. Only when Coppola changed the shooting schedule to bring forward the scene in which Michael Corleone murders a gangster rival and his New York police captain bodyguard over a plate of veal scaloppini were Paramount convinced.

Brando's involvement is particularly significant as there could hardly have been a clearer signal that here was a torch being passed, and the younger man was eager to embrace it. Whereas Brando seemed to mistrust, undervalue and even despise his own talent, Pacino, from the off, has treated his craft with the utmost respect - his name never features in those tales of oh-so-hilarious mooning contests on the Godfather set.

The films he made subsequently - when he would have been offered everything, up to and including Han Solo in Star Wars - reveal a desire to work solely with trusted collaborators: Serpico and Dog Day Afternoon director Sidney Lumet was a friend from New York's Actors' Studio, former teacher Lee Strasberg and John Cazale became recurring co-stars.

His own choice of favourite from this early golden era is also revealing: relative flop Scarecrow (did nothing in America but scooped the Palme D'Or at Cannes) was shot in sequence allowing him to create the character chronologically as would happen in a stage performance. And on stage is where he has always been happiest.

Pacino's commitment to working in the theatre makes him unique among movie stars of his magnitude. This isn't some faded cop show regular doing a six-week IRS-appeasing West End stint as Mr Cellophane in Chicago, it's a 50-year love affair which has seen him tackle everyone from Shakespeare to Brecht, from Oscar Wilde to David Mamet.

He famously fled to the footlights after a cinematic spell in the first half of the 1980s which proved as disastrous as the previous decade had been successful. William Friedkin's Cruising had him as a cop undercover in gay bars. Author, Author failed to replicate the appeal of similarly themed divorce drama Kramer vs. Kramer, which he had turned down several years previously. Hugh Hudson's would-be epic Revolution sank so badly it more or less took the British film industry with it.

Even Scarface, now considered perhaps his most iconic role, was a critical and commercial failure. Hard to believe, given the film's lasting influence (casually but crucially referenced only this year in the world's biggest hit, Uptown Funk, and America's hottest TV drama, Empire) but what we now look back on as a portrayal of 1980s excess was seen at the time as, well, excessive. A typical review from the time sniffed that the star was "just another method boy, going through the motions".

Whether the motivation to return to the screen at the turn of the decade was purely financial or because he felt creatively restored, Pacino was eager to work. A close-to-burn-out cop in solid thriller Sea Of Love and lead villain in prosthetic oddity Dick Tracy served as fairly satisfying build up for the main event, revisiting Michael Corleone in The Godfather Part III.

It's a film with many, many flaws but the central performance isn't one of them, and Michael's grief-stricken howl on the opera house steps remains a career highlight. There were more to come in the reunion with Scarface director Brian De Palma for Carlito's Way, opposite Johnny Depp as a very different kind of Mafioso in Donnie Brasco, and a brace of films with Michael Mann, The Insider and Heat. Scarface screenwriter Oliver Stone allowed him a grandstanding moment or two in the gridiron drama Any Given Sunday.

There was an Oscar nomination for his ferocious turn as Ricky Roma in Glengarry Glenn Ross (the Scottish audience is promised some "surprise readings" at the live show on Tuesday, but Roma's rant at an incompetent colleague will almost certainly not be one of them) and, at long last, a win for Scent Of A Woman. As is so often the case with the Academy, the award came to the right person but for the wrong role - blind retired army office Frank Slade is a juicy part rather than a rounded character. Pacino played the 'for your consideration' game however, peppering the chat show and magazine feature circuit with anecdotes about damaging a retina on location because he had trained his eyes not to respond to visual stimulus. With such hokum are golden statues secured.

In the years since this pre-millennial flurry, the actor's appetite for cinema seems to have dulled. There hasn't been a bona fide classic since Heat, and phoned-in turns with co-star Robert De Niro in Righteous Kill or as part of the already bloated ensemble of Ocean's Thirteen have dulled Pacino's lustre even as they have lined his pockets. Commercials for media companies and donut chains kept the wolf from the door but, continued stage triumphs aside, of late his best work has come in high-end TV. He's developed a relationship with the HBO network and was striking as right-to-die advocate Dr Kervorkian in You Don't Know Jack, tremendous as the title character in David Mamet's stylised take on the Phil Spector murder trial.

Pacino did find some fire in his belly when the time came to bring Shylock to big-screen life in The Merchant Of Venice, a project worth considering in light of the forthcoming Glasgow show - not because of the film itself, but because of an awards circuit event around its release.

At a screening for Bafta members - seasoned film industry professionals, mostly - Pacino took to the stage with his director and co-stars, among them Jeremy Irons. It's fair to say Irons has had better evenings, as he was ignored to the point of irrelevance, of invisibility almost. In the bar afterwards he strolled unmolested as Pacino made his escape through a throng behaving like a bunch of Beliebers with Justin himself strolling among them. This is the kind of star power which the audience will experience when Pacino shuffles on stage in Glasgow, the sheer wattage that lined skin, inevitably crumpled suit and expertly unkempt hair cannot obscure.

It's not unusual for the concert arena circuit to host figures whose fame places them outside traditional critical consideration. People going to see Brian Wilson or Bob Dylan aren't so much attending a gig as ticking off an item on their bucket list, usually getting the T-shirt to prove they've been there, done that. But with Pacino it's different. There are no tunes for the crowd to hum indulgently along with, no backing singers to carry the heavy lifting. It's just him, having a bit of a chat and possibly reciting some Shakespeare. Possibly a "hoo-ha" or a "say hello to my little friend" if a brave soul asks nicely during the Q & A session.

For the audience it will, probably, be enough: Pacino belongs to another time, when stars were still mysterious and unknowable, but not in the studio-sponsored, keeping-Rock-Hudson-in-the-closet sense. No, it's more that his generation pre-dates both the internet and the celebrity gossip industry: he has never been demystified by oversharing on Instagram or getting papped coming out of the gym. He doesn't abandon the red carpet and feed a baying premiere crowd's selfie habit. It would almost be a shame if the good people who stumped up for various meet-and-greet hospitality packages felt the need to distribute photographic evidence of their encounter: take a picture, obviously, but hang it in your home rather than post it on your timeline.

Remember, it's precisely because we can't follow Pacino's every move that you're willing to pay so much to hang on his every word.

An Evening With Al Pacino is at the Clyde Auditorium, Glasgow, on Tuesday. His latest film, Danny Collins, is released on May 29