There is a photograph of John Hume taken in Derry in 1969. He's standing in the middle of a street on his own with his hands raised in supplication as six policemen carrying riot shields walk towards him. His expression is calm despite the obvious tension as he implores them to stop.
It says much about the man. Calm, resilient and yet unwavering in his belief that there is always another way, a peaceful way.
John Hume was born in 1937, the eldest of seven children to Annie and Sean Hume. At the time the family lived in one room of his grandparents' tiny terraced house on Lower Nassau Street in Derry. They moved out when he was four years old, as the family grew.
Educated at St Columb's College in the city and later at St Patrick's College, Maynooth, he had originally studied to be a priest but decided not to continue training for the priesthood.
He spent several summers studying in France: at Saint-Malo, Brittany and at the Institut Catholique in Paris. He received his master's degree from Maynooth in 1964.
After graduating, he began teaching French and History at St Colman's secondary school in Strabane. It was a job he loved, but his talents were such that he would become involved in local self-help schemes and was always busy.
After a few years spent working in a smoked salmon business he set up, he returned to teaching at his old school, St Columb's College in Derry.
When he married Pat in 1960, she had only heard him speak in public once, at a debate where the motion was that "Ireland should join the Common Market". As well as teaching, he spent his free time following Derry City Football Club, or playing cricket for City of Derry.
In her essay for the book 'John Hume - Irish Peacemaker', edited by Seán Farren and Denis Haughey, Pat Hume recalls how throughout the 1960s her husband was active in the local community and was among a cohort of people who established the first credit union in Northern Ireland and the Derry Housing Association.
During this time John and Pat Hume's family grew - Terese, Áine, Aidan and John all arrived. Their youngest daughter Mo was born in 1972. Life was busy and Pat has written that there was no sense of what was ahead.
Civil rights abuses drew John Hume into political life. They were happening all around him. While the Derry Housing Association built many homes, they would meet resistance from local government which feared any change in the city's carefully drawn electoral map.
Throughout the late 1960s, inspired by Martin Luther King who he much admired, Hume and other leaders of the Civil Rights movement took to the streets to demand an end to the gross discrimination suffered by Catholics in jobs and in housing in Northern Ireland.
In 1969, he first ran for electoral office and was elected MP to the Northern Ireland parliament. The following year he was one of the founders of the new Social Democratic and Labour Party (SDLP) with Gerry Fitt as leader and him as deputy leader.
Hume and the SDLP would win their first victory in 1971, when the Northern Ireland Housing Executive was created to manage matters of public housing independently of local divisions. The victory was short-lived, as the Troubles were about to explode.
With the introduction of internment in 1971, the political atmosphere became highly charged. On January 23, 1972, Hume led a march against it on Magilligan Beach, where some internees were being held. According to Pat Hume, when her husband returned that day, he was deeply worried.
"The march had been met by soldiers of the Paratroop Regiment and he had seen that these men were not responsive to reason and had used unnecessary violence towards the marchers. He was so distressed about the risk of serious violence that he pleaded with NICRA (Northern Ireland Civil Rights Association) that the march planned for the following Sunday in Derry should be cancelled," she writes in the book 'John Hume - Irish Peacemaker'.
But the march went ahead - and the day of January 30, 1972, entered the annals of history as Bloody Sunday.
The consequences of it devastated Hume. What was happening in his hometown was now making front-page news all over the world.
Throughout the bloody violence of the years that followed, Hume tirelessly worked for political progress. As Northern Ireland continued to make world-news headlines for all the wrong reasons, it was to Hume that the international media would turn to talk about the crisis.
His ability to explain the complex situation to a mass audience, while sticking rigidly to his message of tolerance, respect and non-violence, meant he was much in demand.
In his own words, he summed up his approach when he said: "Ireland is not a romantic dream, it is not a flag; it is 4.5 million people divided into two powerful traditions. The solution will be found not on the basis of victory for either, but on the basis of agreement and a partnership between both. The real division of Ireland is not a line drawn on the map but in the minds and hearts of its people."
In the 1980s, as the IRA continued to wage its campaign of violence, Hume began secret meetings with Sinn Féin leader Gerry Adams.
A new book published earlier this year on the former SDLP leader's time in America says Hume was bundled into a car and "kept" by the IRA for several days after a failed meeting in 1985, three years before the famous Hume/Adams handshake that many see as the beginning of the peace process.
Not everyone welcomed news of his meeting with Adams. He was excoriated by some and vilified in many sections of the media, where he was branded a terrorist sympathiser.
The pressure on him at that time was immense. It increased further when the IRA blew up a fishmongers on the Shankill Road in Belfast in 1993 and Adams was pictured carrying the coffin of one of the bombers.
A week later, eight people were killed by the UDA in a gun attack in a bar in Greysteel, which was carried out in revenge for the Shankill bombing.
According to Mark Durkan, who succeeded Hume as SDLP leader in January 2001, Hume could feel all the pain and anger from these outrages, much of which was being directed at him.
His health suffered as a result. He lost weight and was exhausted.
But still he persisted. The US dimension to his tireless work in securing peace has been the focus of recent attention. A book and documentary last year by Maurice Fitzpatrick on Hume in America documented his work State-side to enhance the chances for peace.
And while Bill Clinton is the US politician most firmly associated with the peace process, Hume had been laying the groundwork in America for many years - enlisting the help of prominent Americans, including Senator Ted Kennedy.
In early 1994, Hume had pressed Bill Clinton to grant a US entry visa to Sinn Fein's Gerry Adams.
While Clinton acknowledges it was a risky decision, with many in his administration against it, he granted the visa with the hope of advancing the prospect of peace.
Clinton has referred to Hume as the "Irish conflict's equivalent to Martin Luther King".
Throughout all this time, Hume also served as an MEP, where he was committed to using the European Parliament as a place to put Northern Ireland on the map. The practice of consensus politics, he felt, offered a model for NI.
In 1998, after all those years of toil, the Good Friday Agreement was signed. It put in place a blueprint for peace in Northern Ireland and Hume is regarded widely as its principal architect.
Later that year he and David Trimble, who was the leader of the Ulster Unionist Party at the time, were awarded the Nobel Prize for Peace.
In its explanation of the decision to select Hume as one of the joint winners, the Nobel Committee described him as being "the clearest and most consistent of Northern Ireland's political leaders in his work for a peaceful solution".
In his Nobel lecture, delivered in Oslo in December 1998, Hume said the Good Friday Agreement opened a new future for all the people of Ireland: "A future built on respect for diversity and for political difference. A future where all can rejoice in cherished aspirations and beliefs and where this can be a badge of honour, not a source of fear or division.
"The Agreement represents an accommodation that diminishes the self-respect of no political tradition, no group, no individual. It allows all of us - in Northern Ireland and throughout the island of Ireland - to now come together and, jointly, to work together in shared endeavour for the good of all," he said in his speech.
Peace was something he had dedicated his life to achieving. But it had not come without a cost. His health was the price he paid for those years of constant pressure and ceaseless work.
And when celebrations to mark the 20th anniversary of the Good Friday Agreement took place, Hume was too ill to attend.
In a radio interview marking the anniversary of the historic agreement, his wife Pat said her husband's dementia meant he had little or no memory of the role he played in securing peace.
"But personally I hope that somewhere in John there will be a satisfaction that he did his best - and he certainly did," she said.
In addition to his Nobel Prize, he is also the recipient of the Gandhi Peace Prize and the Martin Luther King Award, and is the only person to have been awarded all three major peace awards.