So what is the theory? It goes as follows. The Hero lives in the Ordinary World he longs to escape from. Somewhere very dusty helps, whether it's Kansas or Tatooine. He receives the Call to Adventure from the Herald, traditionally an eagle bearing a scroll, though it often takes the form of a purring Judi Dench. The Hero refuses the Call, but is driven on after meeting the Mentor: cue a swirly-cloaked figure uttering something about destiny. That's Alec Guinness. With his Mentor's help, he Crosses the First Threshold into a special world of magic — or, rather, a world of special effects. He meets his Allies and Enemies in a series of Trials and approaches the Inmost Cave, where he faces the Supreme Ordeal. (Remember Luke Skywalker, along with Han Solo and Chewbacca, trying to rescue Princess Leia from the Death Star?) Almost dying, he Seizes the Reward and then embarks on the Road Back home. In the final act, he faces death again, but undergoes Resurrection. Finally, he returns to where he began, bearing the Elixir of Life or some kind of imperishable wisdom. "There's no place like home", "May the Force be with you", Rose to the drowning Jack in Titanic: "I'll never let go!"

Look at the original format of The X Factor or American Idol and you'll see the mark of Campbell goes far wider than Hollywood. These shows are all about the journey. They start by stressing the ordinary world of the contestant, who crosses the first threshold into the rehearsal room and goes through to the dingy cavern of boot camp. The contestant is then spirited off to meet the mentor on some exotic island before walking out onto the stage for the live shows. This is the supreme ordeal. When the results are announced, our hero is resurrected week after week until the finale, when the winner passes on the wisdom of "live your dreams!" It's such a shame that we know the record label will drop the winner after a handful of hits. The journey has overwhelmed the destination. All must have prizes and today everyone's a hero, meaning no one. 

Despite the law of diminishing returns, Campbell's defence of myth has proved more galvanising for writers (and the paying public) than the academic cult of Derrida. I took my degree in the early 1990s at the high point of post-structuralism, when we proclaimed the death of the author. Who cared what the author said when deconstruction was the key to unlock the power of every text? So we faithfully deconstructed every text to reveal its infinite possibilities, even if every deconstruction led to the same joyful interpretation that every word was, firstly, essentially meaningless and, secondly, a prophesy of Derrida's genius. Modernism had cut us free from the bourgeois noose of narrative and we revelled in our "carnivalesque" celebration of all things plotless and Virginia Woolf. Of course, it was nonsense. Plot didn't die with Woolf, it just upped sticks to Warner Brothers, leaving a fissure that has yet to be bridged between the beautifully written yet rather aimless literary novel and the pacy, entertaining work of genre fiction stuffed full of clichés. 

The main problem with the Hero's Journey is indicated by its other name: the monomyth. Ironically for a theory desperate to prove its cultural plurality and escape from the perceived parochialism of the Judaeo-Christian tradition, it becomes a dogma, monolithic and monotonous. It offers us a McMyth, one that leaves out all the mess, and without the mess — "the fury and the mire of human veins" — there is no magic. Today, writers are learning the McHero's Journey before they have developed any feeling for the real thing. Take the crooked taproot of English poetry, the ballad, in which the central action takes place offstage. Try selling that to Steven Spielberg. Instead, idiosyncrasy, peculiarity — sheer damned dottiness — are replaced with ABC plotting. We see this in Tim Burton's atrocious Alice in Wonderland, where the cold, dead hand of Campbell has replaced Carroll's whimsical dream with a cut-and-paste quest myth in which Alice must slay the Jabberwocky and learn to believe in herself. Girl power!

When you return to the myths that Campbell loved, you discover that none of them tell the entire monomyth. They possess all sorts of kinks and quirks far removed from the suave flow of Star Wars. One dreads to imagine, for instance, what amends the writers of the Gospels would have made if the Hero's Journey had been thrust into their hands. Jesus would break bread at Emmaus, lead his disciples in a chorus of "Circle of Life", take them on a flight around Jerusalem — which would then turn into a spaceship — and finish by exhorting them to "look within, folks!" Instead we get fleeting moments of recognition, whispers of secret teachings and that scene at the end of St John's Gospel when Jesus asks Peter "do you love me?" three times. It is all very odd. But it is a curious fact that when people are sincere they never stick to the point; they surprise us with tangents and unexpected details. It's the well-rehearsed liar who never deviates from the subject. That's why many stories improved by the Hero's Journey ring hollow. Perhaps the answer lies in abandoning our Key to All Mythologies, whether Derridean or Gilgameshian, and returning to the antiquated ideal of the literary canon. Imagine this: a body of different voices, saying things differently at different times with different ideas. How revolutionary would that be?