Clint Eastwood is like God: you see him in everything he touches. A 78-year-old superstar and ten-time Oscar-nominated director/actor/producer, his inviolable “go ahead, punk” machismo lives in the cultural ether, in his pantheon of unforgettable heroes and, especially, in the very fibre of the movies he makes.

In his most recent, the Angelina Jolie period drama Changeling, it’s there in the rousing moment when Jolie’s heroine, Christine Collins, wrongly imprisoned in a brutal psychiatric hospital and facing electroshock therapy, turns to the imperious hospital boss, Dr Montgomery (John Harrington Bland), and defiantly hisses out her most Clint-like line: “F*** you, and the horse you rode in on.”

Collins is the protagonist in a bizarre struggle — based on real events in Los Angeles in the Twenties — over her son’s identity. After he was kidnapped, the police returned to her the wrong boy and coerced her into accepting their mistake. As played by Jolie, with taciturn resolve and tough determination, she is the direct descendant of Eastwood’s own iconoclastic heroes, from Josey Wales to Dirty Harry. In fact, in her toughest moments, such as when she slams the child killer Gordon Northcott (Jason Butler Harner) against the bars in San Quentin prison, Jolie becomes nothing less that Dirty Harriet herself. No?

“I think that would be a bit too fanciful,” Eastwood says with a modest chuckle. “Maybe she was that in her last movie, Wanted [in which Jolie played an assassin], but here she begins vulnerable and becomes strong and persevering.”

Clint Eastwood, you see, is a paragon of humility. He doesn’t do grand totalising theories — or indeed anything that would make it seem as though he had a master plan. He cringes at the word “icon” — “Everybody puts their own interpretation on that, but they are just talking about roles I did many years ago.”

The idea that his output (five personal Oscar wins and counting) involves anything other than North Californian charm and happenstance is seemingly inconceivable to the self-styled bashful legend. “I’m sure that somebody who has laid bricks for 50 years is pretty confident about their job,” he says, when asked about his own talents. “I’m no different from them.”

But scratch the surface and you see in Eastwood an artist of profound intent, and an interior man of fascinating contradictions. Ask him about what directing Jolie involves, for instance, and he replies that he does nothing, trusts his actors, and that it’s always been this way on his famously relaxed sets. But push a bit and the Eastwood method emerges in a telling anecdote about directing Jessica Walter as his psychopathic stalker in Play Misty for Me. “Jessica hated to have her hair messed with, it was really her thing,” he says. “And once I wanted to really have her kind of crazy so I just kind of mussed her hair while the camera was rolling and stepped back. You could see it in her face.”

Elsewhere, concerning his current penchant for female protagonists (see also Hillary Swank’s Oscar-winning turn in Million Dollar Baby) he muses, “In recent times it just seems that women have been relegated to either romantic roles or fluff pieces. So the appeal, for me, is to make a picture about a real woman.”

If he seems unimpressed by modern Hollywood he’s trying not to admit it. But, he explains, he started working in the industry in 1955, when John Ford and Alfred Hitchcock were still on fire. And now? “Nowadays a lot of movies are made for teenage boys, while I’m trying to make films for adults,” he says. “I want to continue making them for adults, but I think we should, instead, bring the teenage boys up to watching adult movies and, er, eh, hee-hee,” he stops himself, giggling instantly at his smutty faux pas. “That’s not necessarily ‘adult movies’, but movies with an adult subject matter.” Of course.

His adult movies have, in recent years, earned him a reputation for bleakness. Mystic River (another Oscar champ) was haunted by paedophilia, Changeling features savage scenes of child killing, while the bloody Second World War drama Letters from Iwo Jima was the proverbial butcher’s window. Is this bleakness within him, and an essential part of who he is?

“No, I don’t think so,” he says, with surety, before adding the tease of self-contradiction, “but I like to explore that.”

He says that he sees himself as a more “glass half full” person. “I lean towards the optimistic side.” Why? “Because I think it’s unhealthy to think the other way. Maybe that makes it calculated, or maybe it’s instinctive. But it’s something that I feel.”

We never imagine Eastwood to be big on feelings, but his early childhood, he says, was terribly lonely. “I was constantly the new kid on the block, trying to adjust, trying to make friends,” he says, describing life in Depression-era California, with his sister Jeanne, mother Ruth and father Clinton Sr, a steelworker whose search for jobs took the family around the state.

“You eventually learn to exist by yourself, to play by yourself and to get along by yourself,” he says, before adding, with curious otherworldly phrasing, “You’re not so reliant on . . . other beings.”

Thus it’s hard not to imagine that the Eastwood who eventually emerged on the big screen — after seven high schools, two years in the Army as a swimming instructor and an early apprenticeship on the pulp western TV series Rawhide — was the literal expression of that same ache and isolation. The Man With No Name in Sergio Leone’s breakout Dollars trilogy was, after all, the epitome of isolated self-reliance (he had a grimace and a theme tune, and a world of inner rage). In fact, could many of Eastwood’s on-camera “icons” (sorry, Clint), from Dirty Harry Callahan right through to Unforgiven’s William Munny, be seen as subtle variants of this same essential Mr Lonely?

“I can’t verify that or not,” he says. “I can’t tell whether the attraction to characters like that comes from the loneliness you’re talking about, or whether the attraction just comes from fantasising about people who are very self-sufficient.”

Eastwood nonetheless parlayed that persona into a 50-year career that bled behind the camera (alternating between action fodder such as The Gauntlet and quirky westerns such as High Plains Drifter) and into politics. A fervent Republican and Reaganite, he became the mayor of the wealthy enclave of Carmel-by-the-Sea in 1986. But his views on politics, as with everything else about him, are more ambiguous today. An opponent of the Iraq war, he says that America’s post-election euphoria is more about hope than hard facts. “I think everybody’s hopeful that we can find solid management,” he says. “Neither candidate was my first choice, but they’re decent people, and now that we’ve got a younger man maybe that’s a good thing — he’s going to need the stamina.”

Typically, Eastwood’s personal life is complicated. Behind the swoonsome leading man image lies a series of romantic entanglements that have resulted in seven children (aged 44 down to 11) from five relationships, including those with the actresses Frances Fisher, Sondra Locke and his current wife, Dina Cruz (with whom he has his youngest daughter, Morgan). Has he learnt anything about women from all this? “Ha!” he says, chuckling at the very notion. “That maybe is something one never ever learns about.”

He adds that his romantic attitudes were passed down to him by his chivalrous father, but that over the years it has boiled down to simple chemistry. “If you don’t like it don’t hang with them, and if you do like it, you hang with them.”

He has regrets too. He says that in the past balancing parenting and movie-making wasn’t always easy. “I didn’t have the knowledge of my older children the way I do of my younger children. But every person has high points and low points in that department. And now everybody’s grown up, and, well, what do you do?”

Finally, for a man approaching his eighties, he says that he tries not to dwell unnecessarily on thoughts of his own mortality. “I think there are certain things that you can’t fight, in terms of your fate. Whatever is fated for you, it is what it is.”

He does add, however, that a key to longevity seems to be a busy life, both physically and mentally. He composes music (his melancholy jazz tinkling can be found on several films, including a beguiling score for Flags of Our Fathers) and, of course, he carries on making movies. Gran Torino (a gang drama in which Eastwood also stars) is already on the way, and The Human Factor (starring Morgan Freeman as Nelson Mandela) is in pre-production.

Eastwood says that he plans to stay busy for some time. “I won’t be retiring unless someone thinks I should retire,” he says. And then he concludes with the boundless enthusiasm of someone without a plan in the world, but with all its energy. “But for now, I like working and I want to tell new stories. I want to find new hurdles over which I can jump.”