THE volley of newspaper headings that greeted the capture of Julian Assange yesterday signalled the opening of another front in the war for truth. In this one though, any claims to moral certainly begin to disintegrate on first contact with the light and are rendered slightly spurious.

Those of us on the left who cling yet to the idea that Mr Assange’s cause – if not the man himself – retains some of its original purity have often had to avert our eyes and hold our noses throughout this decade-long danse macabre. We nurse our sanctimony and take refuge in it though, when the gloating battalions of the Daily Mail arrive at the front firing infamy and outrage like grapeshot. We reach for a tried and simple formula on occasions such as this: it’s usually safe to back a cause if the Daily Mail is against it.

The purity that once sanctified Mr Assange’s mission seemed inarguable. His Wikileaks organisation seemed not only to have provided the coordinates for the location of the Left’s Holy Grail but to some was its actual embodiment. After centuries of fighting the good fight against the cruel caprices of unfettered capitalism and the governments which fed off them here was an agency which had discovered the means to hold them to account and to scatter them.

At last, it seemed that a political and societal tipping point had been reached; that a hole had been punched in the ramparts of the mighty; that truth might now speak to power and be heard. The technology of the 21st century had given us that which Karl Marx, Michael Collins and La Pasionara could never attain: the peaceful means of exposing state-sponsored brutality and murder as well as the persistent corruption at the heart of power.

Even better: it had fallen into the hands of a group which by its very nature seemed to represent an eternal rebuke to capitalism as it disseminated its information for free. It conveyed its information along the synapses of an invisible organism beyond the fearful reach of drone strikes and special forces.

It seemed gloriously appropriate that its first target was the US, a gangster state which has always travelled through the world masquerading as a civilising influence. In this it selectively sponsors and eradicates terrorism on its own whims (usually coinciding with those of its richest citizens) while deploying its vast human and material resources to ensure smaller nations avert their eyes. Those early Wikileaks’ documents and video footage showed us a mighty country loosened from any moral bearings it might once have had while believing that genocide and torture could be purified in the fires of its own distorted sense of righteousness.

Yet even in those early days of Wikileaks, even as the world’s most powerful nations began to tremble at the prospect of more of their darkest secrets being held up to the light, the seeds of its own downfall were apparent in the character of its founder, Mr Assange.

As his global media partners insisted on redactions to preserve the safety of operatives in the field, Mr Assange was exhibiting signs of a messiah complex, insisting on full publication and that his overall cause gave him power over life and death. It was behaviour characteristic of the captains, kings and super-states he sought to bring down.

That he fled the justice of a legitimate investigation into accusations of serious sexual misconduct in Sweden permitted his enemies – until then simmering in their impotence – to re-take the moral heights. It was from this place that they took aim at Mr Assange yesterday and the cause that he represented.

In 2011, in the pomp of Mr Assange’s repute, the Scottish novelist and essayist Andrew O’Hagan was commissioned to collaborate with Mr Assange on his memoirs. Mr O’Hagan’s literary output has not yet received the widespread acclaim in the country of his birth that it deserves. In time though, he will come to be recognised as one of the very best novelists that Scotland has ever produced.

His Assange project never came to fruition, brought down by its subject’s delusions and the self-obsession that seems to have characterised his behaviour inside the Ecuadorian embassy in London these last seven years.

Their encounters though, did yield a vivid and beautifully-expressed essay from Mr O’Hagan in which he details how Mr Assange’s bizarre behaviour scuppered any prospects of a book. It’s a masterful portrayal of how even the most noble of causes can become contaminated by mere human folly.

“I’d never been with a person who had such a good cause and such a poor ear,” the author observed. He also captured something of the habits which seem to have repelled his Ecuadorian hosts. “I noticed he tended to eat pretty much with his hands. People in magazine articles say he doesn’t eat, but he had three helpings of lasagne that night and he ate both the baked potato and the jam pudding with his hands. He turned from being very open and engaged to being removed and sort of disgusted.” Yet Mr O'Hagan's essay also conveyed compassion for the sheer human weakness of its subject.

Referring to Mr Assange’s relationship with that other state whistle-blower, Edward Snowden (now languishing in exile in Russia), Mr O’Hagan wrote: “A fair reading of the situation might conclude, without prejudice that Assange, like an ageing movie star, was a little put out by the global superstardom of Snowden. He has always cared too much about the fame and too much about the credit, while real relationships and real action often fade to nothing.” It is a parable about the dangers of absolute moral certainty.

Perhaps we will never quite get inside the head of this strange, deeply flawed and self-styled truth-warrior and some will assert that even to seek to do so is to accord him more attention than he deserves. Andrew O’Hagan though, comes as close to it as anyone, deploying those gifts that he possesses of divining what moves and afflicts human beings and which illuminate his other works. Perhaps too, when those of us who claim our words and actions spring from loftier principles hold a mirror to ourselves we may find the face of Julian Assange occasionally staring back at us.