As old summits go, Friday's G8 meeting was a successful exercise in noblesse oblige.
Leaders from the eight largest economies of Europe and North America plus Japan summoned heads of government from struggling nations in Africa and the Americas and promised to spend money to help their mothers and children.
Prime Minister Stephen Harper leveraged $4-billion (U.S.) in aid for maternal health from other G8 leaders on top of the $1.1-billion that Canada is committing, and secured a further $2.3-billion in voluntary donations from other nations, the United Nations and the Bill and Melinda Gates Foundation.
Though not all countries contributed equally - and none came close to Canada's contribution on a per capita basis - the maternal health initiative succeeded because G8 leaders share a common world view and can reach reasonable accommodation on areas of potential disagreement.
But the while the G8's common vision led to concrete success, the G20's deliberations Saturday and Sunday will be a messier, though far more important, affair.
Much of Friday's announcement had been telegraphed well in advance. But the proposal for a global tax on bank transactions - a key issue dividing the G20 - is far from resolved.
Europeans are pushing for it. The Americans are interested. Canada has rallied developing nations, whose banks have proven to be far sounder than their European and American counterparts, to stress regulation over taxation. Japan, whose financial troubles are surpassed only by its political instability, can't decide what it thinks.
There are also conflicting opinions about how long stimulus spending should continue, to prevent a recession relapse, and when the priority should shift to deficit reduction.
These are elephantine issues that Toronto must address, if only to frame the debate for the all-important November G20 in Seoul.
Although the Prime Minister deftly handled the maternal-health negotiations, he has no experience chairing a meeting in which opposing powerful interests clash at the table. He hasn't even held a first ministers' meeting. This weekend's G20 will be a powerful test of his negotiating skills.
The G20 will fail, and the world will suffer, if the emerging New Powers, especially China, cannot find common cause with the Old Powers. No other forum offers as much potential to resolve geopolitical conflicts.
Take, for example, Mr. Harper's new passion: foreign aid. South Korea plans to put the issue on the agenda at Seoul.
That decision discredited the notion, promoted by some G8 nations, that the G20 should concern itself exclusively with economic matters. And it sets the stage for a lively debate, for Korean leaders believe the best way to bring a nation out of poverty is to follow their example: develop and then ruthlessly implement technology and infrastructure, relying on social conditions to improve as growth accelerates.
In other words, the best way to improve maternal health is to get women jobs.
This will strongly conflict with the Western notion of developing human, ahead of industrial, capacity. There is more than one debate that is going to have to be reframed in a G20 world.
But give the Prime Minister his due. He defined an anti-poverty initiative - something that is hardly intuitive for him - promoted it, and landed it. A good day.
It is possible that this is the last G8 to be held in North America. The United States plays host in two years, and there is speculation that President Barack Obama will propose shutting the forum down, to avoid distractions from the G20 agenda.
If so, history will record that the last G8 held on this continent committed billions of dollars to save the lives and improve the health of mothers and children in impoverished countries. There are worse way to ring down a curtain.