The music will start at 5 am GMT in Japan, rolling inexorably through stadiums and parks across the world until it reaches a climax tomorrow evening in Hyde Park, where more than 200,000 people will listen to dozens of musicians, old and young, taking part in the most ambitious global concert ever staged. Live 8 has a momentum that has swept before it the cynicism of governments, the bureaucracy of broadcasters and the doubts of internet engineers. There are wild estimates of how many people will listen to the concerts. However, these exaggerate not only the potential audience, but also the world’s fondness for pop music.

To have mobilised this audience and enthusiasm is astonishing, testimony not only to the dogged determination of Bob Geldof and those who pioneered the Live Aid phenomenon 20 years ago but also to the idealism, especially of younger people often labelled as politically apathetic. Concern for Africa will be at the heart of the G8 agenda next week, where Tony Blair will cajole world leaders to adopt measures on debt, aid and trade that will make a tangible difference. Live 8 has not only focused the attention of leaders on this issue, which was already on the agenda, but generally raised awareness of the more complex issues behind Africa’s plight. The concert cannot just be a developed world guilt trip with musical accompaniment.

The scale of the event, however, carries its own dangers. Millions may believe that Africa’s problems — starvation, ignorance, poverty, Aids, war and racial strife — can be solved, or substantially alleviated, with vast sums of money. Live 8’s organisers say they have learnt the dismal lessons of what happened a generation ago. They insist that, unlike the relief of starvation in Ethiopia, they are not trying to raise cash but expectations. They want the Long Walk to Justice to end at the conference table in Gleneagles, where they say it will be up to world leaders to “make poverty history”.

Such a dogmatic approach is almost as misguided as proposals to flood Africa with money that might be embezzled, misspent and misdirected on food aid that would distort markets, ruin farmers and encourage dependency. When the music stops, millions may be emotionally sated; but unless they understand what Africa needs, they will have done little more than assuage their own Western guilt. In particular, the Left, which has campaigned so hard on the alleged exploitation by the West and the inequities of globalisation, needs to understand that simple transfers of cash and resources are futile; indeed, the International Monetary Fund, in an astringent study published yesterday, gave warning that this could stunt rather than foster economic growth.

Instead of numerical targets of outside assistance, what Africa needs, as Live8 itself says in the letter to the G8 leaders which we publish today, are thriving markets, open economies, honest government and the chance to trade itself into prosperity. Locally based micro-loans can help more than any Western plan to reorganise national economies. Curbing corruption and giving free rein to initiative is far more effective than handing out largesse. If Live 8 can make it harder for African leaders to shirk their own responsibilities while focusing attention on the continent’s emerging economies, it will prove valuable; if not, when the music stops, there will be an empty echo.