Book of a lifetime: Heart Of Darkness, By Joseph Conrad

Seldom can an author have achieved his aim for a novel more completely than Joseph Conrad with Heart of Darkness. Conrad once wrote how he hoped to instil enough power in the sombre theme of the book that it would "hang in the air and dwell on the ear after the last note had been struck". Few could argue this is what he did.

More than 100 years after its publication the novel still resonates. Modern film-makers and writers allude to it routinely and some of its contents, like the "the Inner Station", "Mr Kurtz", "The horror! The horror!", are key parts of literary iconography.

Argument begins, however, over the book's sombre theme. The debate is not just ongoing, it is yawning.

Diametrically opposed conclusions are still being prompted. Some view it as deeply racist, while others see it as an attack on the racism of colonialism; some view the book as largely psychological, while others believe it to be mostly historical; some believe it is a critique of the corrupting power of wilderness, while others believe it a parable of humanity's weakness no matter its setting.

Since first reading Heart of Darkness in my teens, I have been drawn back to it more often than any other book. When I was younger I thought it a flight of dark fancy, a fictional Bermuda Triangle where man's moral compass spins wildly. But as I aged, learned more about Conrad and then travelled down the Congo river myself, I came to a different conclusion: that the hellish jungle Conrad described owed as much to history as fiction.

I believe Heart of Darkness was driven largely by guilt. Conrad himself had spent six months working in the Congo in 1890, an inadvertent, almost secret, agent of the first genocide of the modern era. Millions of Congolese were slaughtered to generate revenue for Belgian king Leopold II. They died in frontier wars between his agents and Arab slavers, and were persecuted pour encourager les autres. Colonial agents found a uniquely vile way to increase production: prisoners' hands would be hacked off to show what happens to the disobedient. Ten million are thought to have died. What Conrad saw in the Congo burnt in his soul for eight years until, in a few months, he ran off this most haunting of novellas. Some of its power comes from its eloquent denunciation of the conceit behind colonialism and some from the harrowing thought that humanity has actually behaved like this. But its real power for me is that when I next pick it up, I know I will feel something new.

To continue Conrad's musical metaphor, Heart of Darkness is more score than manuscript and just as no two performances of a musical score are alike, no two readings prompt exactly the same reaction.

Tim Butcher's 'Blood River – A Journey To Africa's Broken Heart' is published by Vintage