To begin at the beginning, there were strong words, two firm statements of intent: the Covenant of Ulster and the Proclamation of 1916. The Covenant was signed by 450,000 men in Belfast one day in September 1912. They pledged to stand by one another to defend "for ourselves and our children our cherished position of equal citizenship in the United Kingdom."
The Proclamation, read to the few bewildered onlookers who watched Padraig Pearse, James Connolly and their troops march into the GPO that Easter Monday, was no less high-minded.
The signatories resolved "to pursue the happiness and prosperity of the whole nation and of all its parts, cherishing all of the children of the nation equally". But strong words, violence and the threat of violence, were in the air. They chimed with the bloody and sacrificial spirit of the age.
The Covenant promised to use "all means which may be found necessary to defeat the present conspiracy to set up a Home Rule Parliament in Ireland". And, given that many of those who signed were members of the Ulster Volunteer Force, the threat was unmistakable.
Fear of a Home Rule conspiracy on one side, and Britain's divisive influence on the other, was to last a long time The Proclamation declared the right of the Irish people to national freedom and sovereignty and its authors' determination to assert it "in arms in the face of the world".
Suspicions ran deep. If the unionists detected conspiracy, the nationalists declared themselves "oblivious of the differences (between majority and minority) carefully fostered by an alien government".
Fear of a Home Rule conspiracy on one side, and Britain's divisive influence on the other, was to last a long time. It seeped through the political wastelands from the 1920s to the 1960s - until the frozen silence was broken by Sean Lemass and Terence O'Neill.
Indeed, it's still behind a barely hidden unionist conviction that its political opponents are too clever by half; behind some nationalists' belief that, whatever the unionists may say, the British government holds the key to all doors.
On either side, whether fired by the Covenant or the Proclamation, only one feeling was stronger than suspicion and fear. It was the unshakable sense of being right.
Neither unionists nor nationalists needed formal declarations to tell them so: the truth was bred in their bones. They were gripped by a political and religious certainty, which some have compared to Stalinism.
Certainly those who'd been steeped in the rhetoric of 1916 were ready to accept the grand assumption in such phrases as "Ireland, through us . . .", the claim by the leaders of the Rising to speak for all.
The first movement that most young people in the South knew and cheered in the 1940s and 1950s was the anti-partition campaign initiated by the inter-party government which declared a Republic in 1949. And if some who took the rhetoric of anti-partitionism at face value set off on a different campaign in the 1950s, that, too, was taken as a natural if over-enthusiastic response to the existence of the Border.
It didn't occur to any of us who tramped through Limerick in Sean South's funeral in the mid-1950s that our view of the unionists - as Irishmen who'd been led astray - could be considered patronising, let alone proved wrong.
And when I went to work in Belfast, a few years later, I felt insulted by several unionist MPs serving in Stormont who had an equally patronising opinion of the Republic; they thought it a squalid and priest-ridden place.
It has taken North and South, unionism and nationalism, an unconscionable time to get to the point where clearer views of each other makes it possible to look forward to an agreement to share this small island.
Of course, it's more complicated than that. And we must all remember the hopes raised once before, when a settlement was attempted at the height of our shameful conflict, only to be shattered by a foolish gesture and the bullying force it unleashed.
The decision at Sunningdale to include a Council of Ireland in the agreement to set up a power-sharing executive - embracing politicians of all shades - gave the Ulster Workers' Council the excuse it wanted to bring the house down.
Others of both loyalist and nationalist persuasions still lurk in the shadows; groups claiming the inheritance of Covenant or Proclamation now bent on preventing even their erstwhile comrades from reaching agreement.
All they retain of the past as they make, carry and set 1,000 lb bombs is an attachment to violence - added to which there is now an indifference to the lives of the people they pretend to represent.
It's one of the reasons why the ritual dance of negotiation seems more frenetic than usual; it may even explain the contradictions between the private positions and public statements of some participants.
Some of those who've carried the heaviest workloads - tireless, patient people like Seamus Mallon, Reg Empey, Seamus Close, Monica McWilliams and David Ervine - seem most hopeful.
A few significant areas where resistance to agreement had been expected have produced mature and thoughtful responses to the prospect of change.
Rank and file members of Fianna Fail were said to be holding tough on Articles 2 and 3. Most of those from Cork and Kerry who appeared on Prime Time during the week were reasonable and fair.
The most outlandish contribution was that of the editor of the Sunday Business Post, who came up with a vision of Bertie Ahern touring the country threatening immediate and terrible war if an agreement isn't accepted.
The most thoughtful long look at the negotiations, their historical and political contexts is provided by Arthur Aughey of the school of history, philosophy and politics, University of Ulster, in the current edition of Democratic Left's theoretical magazine, Times Change.
All they retain of the past as they make, carry and set 1,000 lb bombs is an attachment to violence
He believes that what the Irish and British governments are seeking from the negotiations cannot be described as either unionism or nationalism. "The appropriate term," he writes, "would possibly be stabilism - the objective is to achieve stability and all else . . . is embellishment and detail."
The question to be solved, in Aughey's view, is: "How can local politicians devise a rational and just compact amongst themselves and their communities in order to get out of a nasty and brutish state of nature and thus to secure conditions of peace, putting behind them the fanaticism of historic disputes?"
But "embellishment and detail" may prove highly significant as politicians struggle with symbolism and substance and the risk of failing to distinguish between them increases.
He ends with a quotation from the Duc de La Rochefoucald: "Reconciliation with our enemies is nothing more than the desire to improve our position, war-weariness or fear of some unlucky turn of events."