Johannesburg - The 16th Nelson Mandela Annual Lecture was delivered by former US President Barack Obama on Tuesday to mark 100 years since Mandela's birth.
Obama delivered the 45-minute lecture at the Wanderers Cricket Stadium where about 15 000 people were in attendance.
He said one of the principles Mandela taught him was that "we're bound together by common humanity but I still have to stand here today and say out differences are superficial.
"It's amazing to still have to stand here and do that but it turns out that in reactionary politics, the struggle for social justice not truly finished," he said.
Other speakers included Graça Machel, President Cyril Ramaphosa, Patrice Motsepe and Chairperson of the Nelson Mandela Foundation, Professor Njabulo Ndebele.