US President Barack Obama used his speech to the African Union to pay tribute to Africa’s huge potential, the vibrancy of its youth and the impressive rates of economic growth in some countries. But he added some very direct warnings that this rosy scenario will be harmed by abuse of power by incumbent leaders and the corrosive damage of corruption.

“Nobody should be president for life,” Obama told the startled assembly in the African Union whose members include a large number of presidents who have been in power for many years. Obama warned such leaders that if they think they are the only person who can hold their nation together, they have failed as nation builders. He put his warning in the context of leaders’ responsibility to build strong civil societies, based on transparency and the rule of law, which are essential for nations to grow long-term prosperity. Obama warned that ending the “cancer of corruption” is key to unlocking Africa’s huge economic potential and that the money that is lost to corruption could be used to create jobs and build schools and hospitals, which have a dramatic effect on a country’s economic potential.

And such dramatic growth is not a luxury: The continent’s population of one billion is due to double in a few decades and people will be looking for jobs. This is why Obama said that the rapid economic growth is both changing the “old stereotypes” of a continent hit by war and poverty and also offering its young people a more secure future.