This time last year, the depths of despair were being plumbed at Stormont. The redoubtable Mr John Taylor of the UUP was refusing to touch a draft Belfast Agreement with a barge-pole and offering odds you wouldn't get on a Grand National outsider.
Within days all had changed, changed utterly. Journalists still remember being stirred from their sleep at first light to hear Lord Alderdice, then still leader of the Alliance Party, report in tones of near-disbelief that the deal had been done.
One year on, it still has to be delivered. We are told Gerry Adams cannot deliver IRA weapons, and David Trimble cannot deliver the unionists without them. What this process needs is a good postal service.
That's where Tony Blair and Bertie Ahern come in, yet again. The Seventh Cavalry rides in, on helicopters instead of horses, scattering the Paisleyites, laying siege to the fort and plucking the burning arrows from the heart of the peace process just in time. Marx wrote that history repeats itself, first as tragedy, later as farce; and while there is a fair degree of optimism in some quarters, the possibility of a tragic end this week cannot be ruled out. Certainly the sequence of events up to now has all the hallmarks of a Greek tragedy.
The emphasis placed on prior decommissioning by the Ulster Unionists may prove to be their political undoing. The UUP has staked a great deal on the implementation of a cross-community agreement, and now the political ghost of Brian Faulkner is haunting Stormont once again.
On the nationalist and republican side, whatever remote chance there was of prior decommissioning to facilitate Sinn Fein's entry to government may now have evaporated almost to nothing, although Dublin sources caution that it should not be ruled out. The killing of Rosemary Nelson has sent seismic shockwaves through the nationalist community here.
Questions are being asked: what was the point of agreeing a new political and human rights dispensation last Good Friday if lawyers defending republican and nationalist clients and rubbing the police the wrong way are going to end up being killed? There has not been such anger - especially among the nationalist middle class prepared to make a cautious act of faith in the system here - since Drumcree 1996.
It has been a week full of tragic potential for the RUC. Whatever credibility the force acquired by standing up to violent elements in Portadown has been placed in jeopardy by suspicion and criticism in the wake of the Nelson killing. Hopes of a successful outcome for the force from the Patten Commission report now look somewhat thinner than before.
It is a testing time, too, for the Taoiseach. Leading loyalists are saying that his policy of "tilting towards the unionists" on decommissioning aroused unwarranted and unrealistic expectations in Glengall Street, and contributed to the mess in which the process now finds itself. Others argue that Mr Ahern's approach helped him build up the best-ever relationship between a Taoiseach and an Ulster Unionist leader.
By the end of this week, Bertie could be vindicated as a political genius or damned as a short-sighted opportunist. His admirers are keeping their fingers crossed.
The republicans also face a period of huge risk. They started out as youthful militants, disgusted with the compromise and misjudgments of their elders. If this all goes wrong, they now face the prospect of a new generation of ungovernable youth seizing the initiative on the streets.
Mr Blair is expected in Stormont at teatime on Monday and Mr Ahern has spoken of arriving "on Monday or Tuesday". There will be no mercy for the pair. Mr Blair will also be dealing with the Kosovo crisis, and the media scrum will be an unedifying spectacle.
Ideas and schemes are floating around: the possibility of setting up the executive for an indefinite period with no meetings until decommissioning took place was one proposal mentioned. Another plan was to devise some way for the IRA to decommission that would appear entirely voluntary.
Attention is focusing on variations of the Mallon plan, outlined by the Deputy First Minister to the last SDLP conference, whereby the SDLP and other parties, as well as the two governments, would guarantee Sinn Fein's expulsion if there was no decommissioning within a stated period. The mood in the UUP camp is mercurial. The Washington trip was deemed a success, but the party's a.g.m. last Saturday saw a resurgence of the dissident faction, Union First. Anything short of prior decommissioning will pose huge problems for the UUP, but the alternative to a compromise deal may be the entire process going down in flames.
The current expectation is that the Assembly will convene on Wednesday but a deal on weapons would need to be "precooked" if the meeting is to have any chance of success. The good news is that communication channels are fully open. Gerry Adams entering David Trimble's office for a meeting would be as unremarkable as a canteen staff member wheeling in a tea-trolley. If there is no resolution by Wednesday, Mr Blair may return to London on Thursday. That will open the prospect of another marathon session leading into Good Friday. At some stage, Gen de Chastelain is expected to give his verdict.
There may also be a Drumcree dimension: a visit to the Garvaghy Road by Mr Trimble could help ease tension. At the same time, Mr Trimble has to keep a close eye on potential "bolters" in his team - Dr Paisley, Mr Robinson and Mr McCartney are encouraging UUP Assembly members to join their ranks.
It's that funny, familiar, forgotten feeling of crisis all over again, or as a senior politician succinctly put it: "We have been in this deja vu before."