Obama warns of concentrated economic power
Former US president, Barack Obama says in order to continue Nelson Mandela's long walk to freedom, we'll need to work harder and smarter towards a better society.
He's delivered the Nelson Mandela Annual Lecture in Johannesburg as part of the centenary celebrations in honour of Madiba's life.
Obama says more effort is required to reduce inequality - while we need to promote lasting economic opportunities for all people.
Obama's also urged people around the world to respect human rights.
He says those in power are seeking to undermine every institution which gives democracy meaning.
"Social media once seen as a mechanism to promote knowledge and understanding and solidarity has proved to be just as effective promoting hatred, paranoia, propaganda and conspiracy theories," Obama said.
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Obama says Madiba's light shone so brightly - even when he was imprisoned on Robben Island.
He says the former statesman has been his inspiration.
"And when later as a law student I witnessed Madiba emerge from prison - just a few months after the fall of the Berlin Wall - I felt the same wave of hope that washed through hearts all around the world. It seemed as if the forces of progress were on the march. Each step he took - you felt that this was the moment. All oppression that stunted people's lives was crumbling before our eyes," Obama said.