INGA, Congo - "What did we do before we used candles?"
"We had electricity."
The joke has been told of various countries in Africa, perhaps none so fittingly as Democratic Republic of Congo.
Fresh from its first free elections in more than 40 years, Africa's third-biggest country is trying to get its chaotic economy back on track after decades of systematic looting and violence.
The most recent war, from 1998 to 2003, saw rival rebel groups and foreign armies fight a free-for-all over Congo's rich gold, diamond and copper mines.
But one of the country's greatest assets and one almost sure to outlast any mine, is the eponymous river itself.
With a flow second only to the Amazon, the mighty Congo river spews 42,5 million litres into the Atlantic every second.
Experts said it could generate 40000 megawatts of electricity, more than twice the projected capacity of China's massive Three Gorges Dam, and a major step to keeping up with fast-growing demand for electricity in Africa and beyond.
Pat Naidoo, senior general manager of Eskom, said: "Grand Inga is one of the major opportunities in the world.
"It will eventually be developed to become one of the world's biggest single-site power sources."
This kind of grand talk is nothing new.
For decades Africans and foreigners have calculated the river's awesome power in megawatts and dollars, wondering how much of Africa it could supply given a decent power station and a modern electrical grid.
But decades of mismanagement and corruption under late dictator Mobutu Sese Seko's Zaire and the war that followed his overthrow have kept such tantalising visions out of reach.
With the election in October of President Joseph Kabila, and backing from major partners like Eskom, which produces some of the world's cheapest electricity, the Inga plans have acquired new energy.
The output of "Grand Inga" alone would top South Africa's total electricity production.
At Inga, a section of river, diverted by a channel carved in solid rock, thunders through a row of hydro-electric plants to the valley below. It looks impressive, but most of the generators are out of order.
The national power firms of Congo, Angola, Namibia, South Africa and Botswana hope to build a third power plant at Inga, supplying a new power highway stretching south through Angola and Namibia to link up with a southern African grid.
The new plant could be a useful precursor to building "Grand Inga", the huge power plant that may one day literally light up Africa. - Reuters