"I think I was shot at once at a big festival in Aix-en-Provence," he revealed. "That was when the Maoists were very powerful in France and they resented the fact that they actually had to buy a ticket.

"A lot of them broke down the fence and came into the concert and I did notice one of the lights on the stage go out after a kind of crack that sounded like a gunshot. I don't know. But they're tough critics, the Maoists."

Thankfully, the 8500-strong audience who have managed to secure briefs for his Castle Concert next Wednesday should prove less threatening, although the chances are that Cohen himself will still have an attack of the jitters to overcome before stepping into the spotlight.

Like many great performers, the nerves, it seems, are never far away: "You definitely go into a concert with a prayer on your lips. There's no question about that.

"I think that anything risky that you do, anything that sets you up for the possibility of humiliation like a concert does . . . you have to lean on something that is a little better than yourself.

"I feel I'm always struggling with the material, whether it's a concert or a poem or a prayer or a conversation. It's very rarely that I find I'm in a condition of grace where there's a kind of flow that is natural. I don't inhabit that landscape too often."

Now 73, Cohen has nonetheless enjoyed a long and varied career that has seen him defined as a poet, novelist, singer/songwriter and, for five years, a Buddhist monk. But it is for his work as a songwriter, producing songs laced with a dark humour, which evoke a miasma of longing and despair that he has become best known.

The perceived cloud under which Cohen appears to have lived most of his life has been attributed to many things, including the death of his father when he was just nine. Cohen, however, has frequently claimed that this impression of him is a false one.

As early as 1974 he insisted that his songs weren't born out of any real depression on his part. "I wouldn't call it depression, rather a matter of conscience," he explained.

"My work is always autobiographical, and, I hope, objective. Of course, I am like my songs, but I don't consider myself sad, so I don't think my songs are sad."

And as recently as last year he told one interviewer: "People always overestimated my despair. I never thought my work was darker than anybody else's. I always thought there was a joke here and there that people usually didn't get."

If the death of his father was not the cause of his gloomy outlook, it was arguably the catalyst that sparked his creative force.

Taking one of his father's bow ties, Cohen wrote a few lines of verse on a scrap of paper, wrapped it in the tie and buried it in the garden.

Born in 1934 to a wealthy Montreal family, Cohen may have formed his first band – The Buckskin Boys – at the age of 17, but it was his writing that first made an impact on the world.

In 1956 he published Let Us Compare Mythologies, a book of poetry dedicated to his late father. Another collection of verse, The Spice-Box of Earth, followed in 1961.

Two years later his first novel, The Favourite Game, was in bookshops, although a follow-up, Beautiful Losers, was not as well received.

It wasn't until 1966, when Cohen found himself in New York, staying at the infamous Chelsea Hotel (where he mixed with the likes of poet Allen Ginsberg, Beat-writer Jack Kerouac, artist Andy Warhol and legendary singers Bob Dylan, Joan Baez Judy Collins) that his own singing career began – although his debut was nothing short of a disaster.

Supporting Judy Collins at a 1967 anti-Vietnam war concert, he took to the stage and froze with stage-fright. Thankfully, the encourage-ment of the chanting crowd and Collins herself coaxed him back to the microphone.

Not long after, he was signed to Columbia Records, after which his debut album, The Songs Of Leonard Cohen, immediately garnered him a cult audience.

The albums Songs from a Room (1969), Death of a Ladies' Man (1977), Various Positions, featuring the now anthemic Hallelujah (1984), I'm Your Man, which included First We Take Manhattan (1988), The Future (1992) and Ten New Songs (2001), all followed.

Allegedly not all were "happy" experiences for Cohen, especially Death of a Ladies' Man, a collaboration with the eccentric Phil Spector, of which he recalled, "The time we worked together, one to one, was very pleasant. He is a very hospitable man.

"It was when other people were around in the recording studio that he seemed to move into his Mr Hyde period.

"One day he had a bottle of wine in one hand and a 35mm pistol in the other. He put his arm around my shoulder, pressed the muzzle into my neck and said, 'Leonard, I love you'. At which point I said, 'I hope you really do, Phil'."

It was later reported that Cohen had disowned the album. Seven years on, the album Various Positions saw Cohen return to form with one of his most rapturously bleak classics, Hallelujah.

Even then, it took Jennifer Warne's 1987 release, Famous Blue Raincoat, a collection of Cohen's tracks, and a BBC documentary about his album I'm Your Man to bring him back from the brink of obscurity – as dark as ever.

Although Cohen may never have considered himself a depressive, nine years ago he did admit to a moment of enlightenment when, for the first time in his life he felt "at peace with it".

"I remember sitting in the corner of my kitchen, which has a window overlooking the street. I saw the sunlight that shines on the chrome fenders of the cars, and thought, 'Gee, that's pretty", he recalled in 2001. "I said to myself, 'Wow, this must be like everybody feels'. Life became not easier but simpler. The backdrop of self-analysis I had lived with disappeared."

That realisation came shortly after his five-year spell as a Buddhist monk when, having followed the ways of the Za-Zen Buddhists for three decades, he joined his teacher, Old Roshi, at the Buddhist retreat on Mount Baldy, near his LA home.

"I thought I'd take that opportunity to hang with him while he's still around," he once reflected. "I was interested in surrendering to that kind of routine. If you surrender to the schedule, and get used to its demands, it is a great luxury not to have to think about what you are doing next.

"He named me Jikan after one of his teachers that he liked very much. I was thankful for that but I never quite figured out what it meant. He'd say it meant 'normal silence; ordinary silence'.

"Much of the time, Roshi and I were two buddies drinking. He likes sake, I tried to convert him to French wine, but he was very resistant. But we both agree about Cognac and Scotch."

Modestly, he added, "I always consider myself an extremely bad monk – a sloppy monk, compared to some of the very admirable people up there. Real monks."

And so, 41 years after he released his first album, Cohen's gruff growl will once again entertain in the Capital, some 27 years after his last visit.

What can we expect? Well, in the words of the septua-genarian himself: "I don't consider myself a great singer. I just play the guitar and interpret my lyrics.

"I do what I do because I have a need to do it, to express what I know, and to show people what I do."

• Leonard Cohen, Edinburgh Castle, Esplanade, Wednesday, 7pm, SOLD OUT