When the decommissioning of IRA arms was announced last Monday, I turned to Ed Moloney's book The Secret History of the IRA, and reread the chapters dealing with the evolution of the Adams-McGuinness peace process from its genesis in 1982-83 to the year 2001, when that book was completed, writes Garret Fitzgerald.
His account explains why this process has taken such a long time. It makes it clear that there has been huge resistance within the IRA to acceptance of the consent principle in relation to Irish political unification, to the idea of joining with the unionists to govern Northern Ireland within the UK and to the abandonment of the "armed struggle".
And even when the opposition of IRA members to these aspects of the process was finally worn down, there remained bitter hostility to the idea of decommissioning their arms, for which there was no precedent in 20th-century Irish history. Overcoming resistance to this proved to be one of the most difficult elements in the whole process.
It may be the case that Adams and McGuinness initially believed that they could get away without arms decommissioning. They certainly convinced at least one of those with whom they were negotiating that there could be no decommissioning: I recall being told this most unequivocally some years ago.
The two leaders may also have believed at the outset that they might not have to commit their organisation publicly to the abandonment of criminality.
Last December they seemed momentarily to have got away with this, for even after the IRA had refused to make such a commitment Bertie Ahern and Tony Blair briefly continued to claim that the only remaining obstacle to an agreement was the IRA's failure to accept photographs being taken of decommissioning.
But when Mary Harney and Michael McDowell pulled the rug from under any such half-baked deal, both premiers had to climb down smartly.
At least since 1993 Adams and McGuinness and some of their close allies have known that a successful peace process must include, in addition to complete abandonment of the "armed struggle", acceptance of the consent principle in relation to Irish unification and participation as partners with unionists in the government of a Northern Ireland that would remain in the UK for the foreseeable future.
This was, and had to be, the position of the two governments. And to those who watched this prolonged process from outside it was self-evident that this was the only possible outcome.
It has, therefore, been difficult for public opinion in this State to grasp the fact that throughout almost all of this period most rank-and-file members of the IRA were blind to this reality. They remained in denial, partly because within a secret organisation of this kind the reality of the world outside is often opaque; but also, as Ed Moloney's detailed account makes abundantly clear, because their leaders succeeded in persuading them for years on end that such an outcome as this was not envisaged and would not happen.
The consequence of this was that for much of this time what was obvious to everyone else who followed these events was not understood by those most deeply involved, who apparently continued to be convinced that the prolonged negotiation was a front put up by their leaders as part of a scheme to confuse and mislead the British, rather than being a serious effort to end the "armed struggle".
As late as January 1998 when proposals along these lines were published by the two governments, Adams and McGuinness, as well as the army council, sought to reassure the IRA membership by condemning these proposals as a sop to unionists, and Sinn Féin published a counterproposal for an all-Ireland government.
Consequently, three months later IRA members were bemused to find that what had been flatly condemned in January had in fact all along been the actual basis of the negotiation and had now formally been agreed to by Sinn Féin.
To bring the activists along with them to accept what they had been told would never happen was no easy task for Adams and McGuinness, and the length of the softening-up process was greatly extended because, to secure reluctant acceptance of the Belfast Agreement, they found it necessary to tell their adherents that the agreement, including its reference to decommissioning, was merely a tactical move.
In addition to this the IRA issued a statement saying that they would never decommission. Subsequently the "Colombia Three" adventure and the Belfast bank raid may also have been designed to offer reassurance to a restless IRA membership.
Eight years have now elapsed since Adams and McGuinness finally defeated their opponents on the IRA executive and secured authority for the army council, led by them, to control the negotiation that led to the Belfast Agreement. This long period has been necessary to bring Sinn Féin to the stage of tolerating both decommissioning and an unambiguous renunciation of criminality.
At times those of us watching have been impatient about this prolonged process, and have been inclined to accuse Adams and McGuinness of dragging their feet.
But throughout this period they and their immediate colleagues must have been as frustrated as the rest of us. It cannot have given them any satisfaction to have had to postpone from 1998 to the year 2006, or perhaps even 2007, Sinn Féin participation in a solidly established Executive in Northern Ireland.
We will have to wait to see how the rank-and-file of the IRA react to the decommissioning. But such indications as are available seem to suggest that a further split, or a rush of members to join the "Real IRA", established after the Adams-McGuinness internal victory in October 1997, is now unlikely.
If this proves to be the case, the delaying tactics employed by Adams and McGuinness since the Belfast Agreement will have been vindicated. So also, I believe, will be the decision that I made as taoiseach in early 1983 to initiate the process that led to the 1985 Anglo-Irish Agreement, the 20th anniversary of which is imminent.
Of that agreement, Ed Moloney has this to say: "The IRA's continuing violence put a natural limit on Sinn Féin's appeal [to Northern voters]. Another reason for the fall in Sinn Féin's vote was the Anglo-Irish Agreement of November 1985. The agreement - which Dublin's diplomats skilfully used to smooth the rough edges of Britain's security policy - injected new life into the SDLP and stabilised nationalist politics.
"From then on it was clear that, short of another hunger strike or Bloody Sunday, Sinn Féin's vote would never rise much above the 80,000-90,000 mark again.
"The Anglo-Irish Agreement had created a stalemate in the competition between the two nationalist parties, and this was to make it easier for Adams to argue among his close advisers that only a radical departure could break the logjam."