When George Mitchell launched his draft paper for an agreement on Monday night, he used a climbing analogy to explain the numerous pitfalls and obstacles that had to be avoided or overcome to reach that stage of the process.
It reminded him of the first time he climbed a mountain in Maine. After hours of hiking through the foothills he finally came to what he thought would be the pinnacle. But all that he had climbed was a ridge, far ahead of which was the summit.
The parties may now have reached the actual summit with this agreement but, instead of a clear panorama in front of them, what they see is a mountain range. There are a few more summits to be scaled before a clear, pleasant vista opens up.
Politicians may be exhausted, but they must conserve some energy for the coming months. The next pinnacle is the referendum in late May. After that comes the election to an Assembly in June. And after that is the dread prospect of the marching season. Twenty-five years ago it took equally gargantuan efforts to achieve the Sunningdale Agreement. But when it was put into effect it was destroyed by the Ulster Workers' Council strike, with loyalists and unionists operating in unison. That came after the signing of the deal. Similar problems lie ahead after this agreement is signed. Any one of the current three obstacles - referendum, election, parades - could smash the current deal. There are important differences this time. The UDA and the UVF, who helped wreck Sunningdale, are part of this deal through their political representatives.
There is consensus among all the parties that, if a deal is to get through, the referendum and election must take place in quick succession. The referendum is pencilled in for May 22nd. The run-up will be gruelling. The UUP will face tough opposition from unionist opponents, within and without the party.
The SDLP and Sinn Fein must weather the pressure from republican dissidents. The forces of extreme republicanism and unionism will fight hard and dirty, and it will take strong resolve and nerves for those in favour of the deal to withstand that pressure.
The referendum campaign could also be waged against the backdrop of violence from the Continuity IRA, the INLA and the LVF. But if Mr Trimble, particularly, remains resolute, and if Sinn Fein equally supports the referendum, whatever its reservations, it should pass.
Next, though, comes the Assembly election, scheduled for some unspecified date in June. The great fear among supporters of the agreement is that while it will be carried in the referendum, candidates opposed to the deal will be elected to the Assembly.
If an anti-agreement bloc of the DUP, UK Unionists and disaffected UUP members won more seats than the pro-deal unionist supporters from the UUP, the Progressive Unionist Party and the Ulster Democratic Party, then it would be very difficult to create a workable Assembly co-operating with the North-South bodies.
The result here is vital. At this stage it's very hard to know whether the pro- or anti-agreement unionist forces would triumph. It's all down to the mood of the unionist people, and whose line they are prepared to accept. If the arithmetic works in Mr Trimble's favour, then there is good hope of stability.
During the marching season, the hope is that with a new political dimension those at the cutting edge of the parades dispute, especially from the nationalist side, might be prepared to also cut a deal.