AS I write this, as you read it, we can be almost certain that Martin Scorsese is watching a movie. The time zone doesn't matter; he may be in his native New York, or his adopted home of Los Angeles, perhaps in Boston or Japan, the settings for his next two films; it may be midday or midnight, but we can imagine Scorsese sitting in darkness, alone, light waltzing across his face, that nose with the flattened bridge, those extraordinary wolf-tail eyebrows, while he screens a beloved print. It may be Citizen Kane, the film that made him want to make films; it may be On The Waterfront, East Of Eden or Olivier's Richard III, a triumvirate he worships over and over again. John Milton is said to have been the last man who had read every book; it is possible that Martin Scorsese has seen all the films - at least, according to Leonardo DiCaprio, he has seen every film made before 1980. Scorsese

is obsessed with cinema. No, Scorsese is cinema. It's inside him; he contains multiplexes.

When I was told that he had agreed to an interview, I decided to ask what the Scorsese of 1975 would think of Scorsese in 2005. It would be aninteresting way, I thought, of discovering whether he agreed with those critics who believe that he did his best work in the Seventies when he was a youngblood making Mean Streets and Taxi Driver, and that more recent films have been anaemic in comparison. Instead, though, he says, "I'd want to see his films. I'd want to see what Scorsese was going to do. I'd like to see what he was going to do with a bigger budget.

I'd want to know what stories he was going to tell, and how those stories were going to be told visually. That's interesting to me. I like seeing, let's say, Truffaut's work from the beginning to the end, you know? I find that fascinating."

Typical Scorsese to want to see an entire life's achievement. He is a completist. He collects prints of movies, first editions of novels, he has an impressive back catalogue of ex-wives and girlfriends; when he was taking drugs, he seems to have tried to take all the drugs. But he's right, to watch his films in total is fascinating.

Since 1963, he has directed 19 features, plus various shorts, documentaries, commercials and music videos. Watched consecutively, themes soon emerge; in Scorsese's pictures, a lot of men have a lot of trouble with women, and a lot of those men are played by Harvey Keitel orRobert De Niro. There is also a compulsiveness to some of Scorsese's images. In film after film after film he has men examine themselves in mirrors - Charlie in Mean Streets, Travis Bickle in Taxi Driver, Jake La Motta in Raging Bull, right up to Howard Hughes, the subject of his latest film, The Aviator. Scorsese's is a cinema of self-confrontation - his protagonists confront themselves in the films, and Scorsese confronts himself through the films, exploring his own problems and shortcomings. None of this is accidental or subconscious. He does it deliberately. So when you start out talking to him about his work you quickly

find yourself knee-deep in neuroses.

When that happens there is only one thing to do: wade in.

MARTIN SCORSESE walks into a drawing room of London's Dorchester Hotel behind Leonardo DiCaprio. If his old pal George Lucas was here, he might observe the resemblance to R2-D2 and C-3P0 - DiCaprio, the six-foot-plus golden boy, followed by the stocky, neckless, five-foot-three director. But both have equal presence. DiCaprio wields that kind of extreme fame and beauty which sucks all the air from the lungs of those who see him, but Scorsese has an aura of power and talent, akin to that of a political or religious leader, which is just as magnetic. Rows of seated journalists stare at them both, eyes flicking from one to the other like executive toys.

Scorsese is 62, DiCaprio 30, and it is the younger man who bows the knee. For years he has genuflected at the altar of Marty. He has studied the films as if they were scripture, decorated the office of his production company with religious relics (the boxing gloves worn by De Niro in Raging Bull) and even changed agent so that he would have the same representation as the filmmaker. It has paid off. Scorsese cast him in Gangs Of New York, agreed to direct The Aviator (a project which DiCaprio had nurtured) and will direct him again in The Departed, a gangster flick set for release in 2006.

DiCaprio's Titanic was released on the same day as Scorsese's Kundun, and it was the latter which sank without trace, but the director has no lingering resentment. "If there is any doubt that Leo DiCaprio is a serious actor, " he says, "The Aviator puts those doubts to rest."

The two men take turns to answer during the press conference.

DiCaprio is confident, his voice slow and deep, his forehead forming a gnomic pattern when he frowns. Scorsese, by contrast, seems ill at ease.

He dabs his brow with a white handkerchief, swallows a couple of pills, possibly for his asthma, starts to take his jacket off then abandons the project, gabbles and gabbles and gabbles. His grey hair is scraped back from his forehead and he wears thick black glasses; he used to look like Charlie Manson, now he looks like Woody Allen.

He explains that when he was making The Aviator he thought about Howard Hughes in terms of Greek mythology, particularly the story of Daedalus and Icarus.

Hughes was America's first billionaire. He inherited vast wealth from his father, who had invented a revolutionary drill bit used in the oil business; from his mother's side he inherited an obsessive-compulsive disorder which made him terrified of germs. He was 18 when he came into his fortune, and throughout the late Twenties worked relentlessly on the epic Hell's Angels, the most expensive film ever made when it was released in 1930.

After Hell's Angels, Hughes became more interested in aviation than filmmaking, took over TWA, and worked on developing planes. He suffered a near-fatal crash in 1946, and throughout the remainder of his life became increasingly reclusive, his obsessive-compulsive disorder taking over his mind, resulting in the popular image we have now of him as a wild man with long fingernails, locked in a dark hotel room, bottling his urine and wearing empty Kleenex boxes on his feet. He died in 1976.

"Throughout his whole life he tries to escape from the labyrinth, " says Scorsese. "But he is the labyrinth and the minotaur. He's his own monster."

ABOUT AN HOUR later, Scorsese walks into an upstairs suite, all business, shakes my hand and sits on the couch. He's immaculately dressed in a dark blue suit. Even in his wild, bearded days, Scorsese - whose father Charles was a tailor and mother Catherine a seamstress - was always a vision of good tailoring. When he went to Woodstock in 1969 to work on the film of the festival, he wore a blazer while all around was nudity and mud; in the early Seventies, he would hang out on Nicholas Beach, outside Malibu, becalmed on the sand in a white suit while the cream of the new Hollywood went skinny-dipping.

We begin by talking about being a man apart. Immediately after The Aviator, Scorsese started work on a two-part documentary of Bob Dylan, which will be screened on the BBC later this year. Dylan and Howard Hughes are similar, I say to him, in that both became hugely famous because of their talent and innovations, and both later recoiled from the limelight to lead hermitic, hermetic lives. Can you relate to that?

"Absolutely, absolutely, " he says, having visibly restrained himself from leaping in before the end of the question. "Yeah. Yeah. Yeah. It's a very interesting thing. When I was younger I would be trying to do my work, and going around the world and wanting recognition. I still want recognition, there's no doubt about that, but in the last 15 years I have tended to pull back. There have been periods in my life where I have gone off pretty much by myself, you know, so I understand the need to be reclusive, the need to think.

"There's my age, too. I'm 62 with a family, a child who is five years old, and a wife. I need time with them, and time from them also, for myself."

It would feel a bit trite to compare Scorsese with Hughes except for the fact that the director always needs to find some kind of personal identification with his lead character before he can make a film. In the case of The Aviator, Scorsese says that one of the main reasons he agreed to make it was so he could shoot the scenes where Hughes is alone in his screening room watching films. Towards the end of his life, Hughes holed up in the Desert Inn, Las Vegas, watching movies all night, having bought the local TV station so he could specify what they aired. During a discussion of the making of Casino, Scorsese mentions in passing that to escape from the tensions of the set, "I'd lock myself in an empty house in Las Vegas for the weekend and look at old 16mm prints all night."

This was not unusual behaviour for him. In the late Seventies, Scorsese would host screening parties in his garage, showing a number of films each night. The place was soundproofed, blacked-out, unventilated; the guests high on cocaine. At other times, home alone, he would walk around the house, a different film playing on a different video in each room.

He still enjoys being alone with films. "There's no doubt that I look forward to it as a kind of ritual, " he says. "At least one day a week I project a film, sometimes just to look at a print, to see it projected in front of me.

A lot of times I just sit in the screening room and don't even watch it really. Reclusiveness is a good thing because you need time to think."

It's interesting, this joyful shunning of the world. It may be the same impulse which fuelled Scorsese's early decision to become a priest; he even entered a seminary for a while, although sex lured him out. His films are full of religion, most explicitly in The Last Temptation Of Christ, but for him cinema is religious. He was raised in Little Italy as a Catholic, and remembers that when he was taken by the priest to see The Robe, the score became confused in his mind with that of the Mass for the Dead. Since then cinema has been, for him, a kind of communion with the eternal, and filmmaking itself a transubtantiation, cells into celluloid.

Scorsese's yearning for isolation may also have something to do with his cloistered childhood. He was a sickly child, plagued by asthma and allergies, self-conscious about his frailty and lack of height, insecure about his looks. Instead of playing outside with other neighbourhood kids, he spent a lot of time at the cinema with his father, "an avid movie-goer".

We talk more about Hughes; Scorsese agrees that his mania, his insistence on perfection, both made him and eventually broke him. I ask whether to be a successful director or producer in Hollywood actually requires a degree of functional madness.

"Oh yes, I think so, " he says.

Has he ever been so focused on something that he felt he was losing his sanity?

"Yes, " he laughs, shaking his head. "During the Seventies, New York, New York and certainly the editing stages of Raging Bull were very difficult for me. My life was difficult, not the editing. Not the editing."

Scorsese started using cocaine during the 1976 filming of New York, New York, a musical starring Robert De Niro and Liza Minnelli, with whom he became involved. The idea at first was that drugs would allow him to access emotions which would help with his work, but instead he lost focus, took on too many projects at once and New York, New York became his first flop.

Eventually he was taking coke just to see how much he could take before it killed him; one weekend in September 1978 he very nearly found out. He started coughing up blood, blacked out. It was discovered that he had no platelets in his blood, the result of a bad mixture of cocaine and asthma medicine, so was bleeding internally and close to having a brain haemorrhage. He had become a monster in a labyrinth of his own creation.

Onrecovering, he threw himself into making Raging Bull, the brutal yet beautiful boxing film now widely regarded as his masterpiece. "I had actually almost died, but by some stroke of fate it all worked out, and I didn't die, and I was making this movie, " he says. "I didn't give a damn what was going to happen to the picture. I just wanted to put everything in it. And I was really angry. An anger that was very, very productive. I knew that it would probably be the last picture I made."

Because you thought you were going to die?

"Besides that. I just felt that there wasn't any place for me any longer in filmmaking. Particularly in America."

Raging Bull was a box office failure, as was his next picture The King Of Comedy, even though it featured what is arguably De Niro's greatest performance, as the wannabe comedian Rupert Pupkin.

There's an intensity and violent edge to Scorsese's work that has perhaps harmed his commercial prospects ("The kind of movies I'm making are not Polar Express") and may be responsible for the astonishing fact that he has never won a Best Director Oscar. And even when his films aren't particularly violent, they feel as though they could become so at any moment. This probably has something to do with the ubergrouchy atmosphere in which they are created. "Last Temptation Of Christ was very difficult, " he grumbles. "Goodfellas was pretty annoying to shoot. Casino was an annoying picture." There are stories of him losing his temper on set; one has him sitting in his trailer, listening to The Clash, getting more and more wound up, then bursting out and throwing chairs around.

"The anger is not just at a person or the system, " he says, "It's also at myself. It's always there. I'm always in something of a bad mood, ha ha! I can't help it. There's always a certain anger that goes into my work. As you get older, maybe the anger is less overtly expressed, and works against the story, keeps the tension going when you're lining up a shot or directing a scene." He bites down on that word tension. "There's still a great deal of it.

That's why I do a lot of humour. A lot of humour. You have to because the whole thing's absurd. It's absurd. I'm absurd."

Absurd?

"Yeah. In a sense, you're just absurd.

What are we doing here? I mean here we are living, breathing; we seem to be conscious." He shakes his head, amused and despairing, Albert Camus in Armani.

Where does the anger come from?

"It comes from being human, just from being alive. It's something that can be destructive; it can certainly kill, it can eat away at you. But it can be constructive. Sam Fuller said you should only make a film if you're really angry."

Scorsese once took lithium to control his rage but now he seems to regard it as a good thing; like Tam O'Shanter's wife, he nurses his wrath to keep it warm.

"There are things that get me mad. But I react to them differently these days, ha ha ha ha ha! Because if I didn't, I don't think I'd be around.

I get myself mad. I am mad about myself constantly, and that's why I do comedies, work on other films. I did a commercial for American Express with a lot of humour in it. It's pretty funny, I must say. Have you seen it?"

I tell him no, and he starts to act it out for me.

"I play myself going into a One Hour Photo place in a drugstore and asking for my photographs that I took at my nephew's birthday party, " he grins. "Then I'm looking at them, going ?" and here he slaps his open palm, "'Oh my God, what have I done? Look at this!'

"The kid behind the counter looks at it. 'What do you think about that?' I ask. 'It's good.' 'You think that's good? Look at the composition!'" Scorsese karate chops the couch.

"I'm throwing the pictures round and going completely out of my mind. It is based on myself because I'm constantly doing that anyway."

Suddenly, he's being serious again, and his eyebrows return from somewhere around his hairline to their customary position, shrouding his eyelids. "Anger's important. It can destroy you but you can channel it into expression. That's the key. If you don't get angry, if you don't feel strongly, don't make the picture. You'll see, there'll be no heart in it."

He has put so much heart into his work that often there isn't much left for the people around him, and this has had serious consequences for his personal life (indeed, one of the great themes of his films is the difficulty of balancing love and work). Scorsese has been married five times, and has three daughters. "In 1999 he married his current wife Helen Morris, an editor at Random House who he met when they worked together on a book published to tie-in with Kundun; they have a five-year-old daughter Francesca, for whose benefit - and also to fulfill his need to work on comedy - Scorsese agreed to voice a puffer fish in the animated film Shark Tale.

Scorsese has a tendency to become obsessed with certain projects, unable to let them go. The Last Temptation Of Christ, for instance, came out in 1988, but he had been thinking about making it since 1972.

Similarly, he first decided to adapt Herbert Asbury's book Gangs Of New York in 1970 but didn't start shooting until 30 years later. Then when he did start, he found he couldn't stop.

"Gangs Of New York was the last picture I made obsessively, " he says.

"It got to the point, honestly, where the studio people would come in and talk to me, and I would refuse to understand what they were saying, refuse to understand, until they looked at me and said, 'No!' Literally.

That went on until the last day of shooting. There was something in the nature of that film that meant I could just keep making it."

Gangs Of New York concluded in 1863, but Scorsese says that ideally he would have shown the next 20 years until the Brooklyn Bridge was completed, linking the island of Manhattan with the American mainland. "That would have been the idea, you know, another ten hours or something. That was an all-consuming film."

He says that he has finished with epics, that he will now make films on a much smaller scale, but remains enormously busy. Back in the Seventies he promiscuously took on projects because he was high on coke and ego, believed he could do a hundred things at once; and because he also believed that he would not live to be 40, he felt that he had to cram as much achievement as possible into what was going to be ashort life. Now at 62, he is still acutely aware of death somewhere up ahead, and is desperate to continue to rack up films. During our conversation, he repeatedly uses the phrase "in the time that's left to me".

He has his portrait of Dylan to edit, plans a documentary on the history of British cinema, and another on the controversial filmmaker Elia Kazan. Then there is The Departure, to star DiCaprio and Matt Damon, a planned adaptation of Shusaku Endo's novel Silence, and a film of James Boswell's London Journal. He also continues to campaign for the preservation and restoration of film prints, and is trying to read his way through ancient literature and history, a new obsession that has come to him late in life.

"My problem is that I want to do everything, " he says, finally, as his publicist enters with lunch. "I wanted to do Alexander The Great, and Oliver [Stone] said, 'Oh no, I'm going to do it.' You know, he said, 'You like the Romans. You don't like the Greeks.' I said, 'I do like the Greeks!'

'No, ' he said. 'You like the Romans! I know you!'" The Aviator is out now