What makes Steven Spielberg a cinema icon? The unromantic answer is numbers - big, fat box-office numbers with more zeros than he can probably be bothered to count, and a personal fortune that is estimated to be more than $2 billion. The reason these numbers stack up so impressively is nothing to do with marketing or focus groups, it's due to the fact that Spielberg is still in touch with the child who fell in love with film in the first place. He has retained the sense of wonder we feel when movies are the closest thing to magic that we have experienced.

Spielberg showed an early aptitude for cinema. His first film, made when he was 12, was an eight-minute Western called The Last Gun, but Spielberg rapidly became more ambitious. By the age of 14, he had mastered rudimentary special effects. In his short film, Battle Squad, he managed to make footage shot in a stationary aircraft appear as if the plane was flying; within two years, he was working on a 140-minute sci-fi movie about a UFO attack.

By the age of 22, Spielberg had a seven-year contract with Universal studios, which he had won on the strength of yet another short film, a girl-meets-boy odyssey called Amblin. Spielberg took the title of this short and used it as the name of his first company, one of many examples of the director incorporating autobiographical elements into his work. Throughout his career, he has tended to return to the stories that intrigued him as a child, specifically war and alien visitors. Another recurring theme is the motif of the distant or absentee dad, mirroring Spielberg's childhood relationship with his own father.

Universal put Spielberg to work directing television dramas, but it didn't take long before the cinematic prodigy had broken into films. His first real success was the made-for-TV film Duel, a fantastically tense, brilliantly simple cat-and-mouse story about a salesman driving on a highway who realises that the mammoth petrol tanker hanging on his tail has murderous intentions.

His next major breakthrough was his first big-budget film, a baptism of fire into the high stakes world of blockbuster production. The film was Jaws and the shoot was so beset with problems that Spielberg was nearly replaced as director. A faulty animatronic shark accounted for most of the stress, meaning that the giant great white is not shown in the film nearly as much as had originally been planned. Spielberg instinctively realised that it would be more effective to use the camera as the shark, a decision that ultimately made the film far more tense than it would have been had he used more footage of the rather creaky-looking fake shark.

Nevertheless, Spielberg was far from confident about his film. It is reported that he only realised he had a hit when he witnessed an audience member run out of the theatre to vomit after a shark-goring scene, only to return to his seat immediately afterwards.

Jaws was the first of many Spielberg films that would in some way change the course of modern cinema. The first film ever to reach the coveted $100 million box-office milestone, Jaws is credited with establishing the 'summer blockbuster' tradition.

Jaws was followed by a string of successes. Close Encounters of the Third Kind was an esoteric alien movie, a one-off that was described by its famously self-medicated producer, Julia Phillips, as the film that 'anyone who ever dropped acid and looked up at the sky for a while was waiting for'.

And Spielberg demonstrated his instinct for assessing box office potential when he was one of the few people to predict that Star Wars, his friend George Lucas's film, would go on to gross far more than his own take on alien visitation.

It was an instinct that stood him in good stead repeatedly. The boys' own adventure story Raiders of the Lost Ark was swiftly followed by E.T: The Extra Terrestrial, an irresistible futuristic fairytale that, for a while at least, was the highest-grossing film ever. But however loyal and enthusiastic his fan base - he was and is unique among directors and on a par with top movie stars in that his name alone could 'open' a film - critics and the film establishment tended to deride his films for their sentimentality. Spielberg responded by growing up - the fact that he has made films such as Empire of the Sun, Schindler's List and Saving Private Ryan alongside crowd-pleasers like Jurassic Park, while developing and producing countless other ideas, goes to show just how extensive his understanding and love of cinema, in all its many and various forms, has come to be.

What makes Spielberg so consistently great is the sense that, however much money he makes, filmmaking for him is a passion first and a business firmly in second place.

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