Handshake will mean nothing without action
Will that handshake be a truly historic moment, or just a footnote in history below the ceasefires, decommissioning and power-sharing?
Certainly, the visual image will last. Martin McGuinness's instincts were right when he opted to have pictures taken.
Much of the impact of Sir Patrick Mayhew's first ministerial conversation with Gerry Adams was lost because it took place in an anonymous Washington Hotel room. Sir Patrick emerged, looking flustered, to confess to the encounter on a crowded landing.
The full impact of IRA decommissioning was also blurred and delayed by the absence of photographs.
Even with distinguished witnesses it gave room for speculation and rumour, which took some time to dispel.
The same would have happened after a meeting with the Queen in the absence of a visual record. Dissidents would have speculated that he had bowed and scraped, or even been slipped a medal.
The greater the transparency, the greater the impact.
McGuinness's claim that he has symbolically grasping the hand of every unionist would not have been taken so seriously if no one had seen him doing it, or if he had seemed, like Sir Patrick, to be a little ashamed of the whole thing.
The whole exercise is, however, only worthwhile and will only be more than a footnote if it is followed through by actions aimed at building one community.
The big test next week is to produce a Cohesion, Sharing and Integration (CSI) strategy.
That will mean both Sinn Fein and the DUP using this opportunity to stretch their support base to achieve change which, like the handshake, will begin to seem inevitable and right once it has happened.
So far, the omens aren't good. We have been promised a strategy since 2007 and a first draft, produced in 2010, impressed no one when it went out to consultation.
Last month, the Alliance party, normally not known for causing trouble, walked out of the working group, saying that nothing worthwhile was likely to emerge.
It is up to the big parties to prove them wrong, but here again the omens aren't good.
Both Sinn Fein and the DUP are verbally on board for a shared education system, but what they seem to be giving us is a shared-out one, where both communities and both sets of clergy get a say on their own side of the fence.
When it came to making cuts in teacher-training, a Sinn Fein education minister, John O'Dowd, made Queens University - where training is religiously integrated - bear the brunt of the reductions. When he doled out funds for school building this week, the integrated sector missed out on a share.
This is just one example. The building of effectively segregated housing is another example of the shared-out approach.
Sharing-out is better than communal domination, but it still leaves the divisions that led to conflict intact as a toxic legacy for another generation.
Gestures and historic photo-opportunities are brave and valuable. Yet their full potential will only be realised if those who make them subsequently show the courage to lead real social change.
Next week provides an opportunity to do just that.