Obama, 56, has made an art of criticising the current president's values without explicitly naming Trump, and he peppered his speech with warnings against protectionism and racial nationalism, CNN reported.
"You have to believe in facts", Obama said. Without facts there is no basis for co-operation. "If I say this is a podium and you say this is an elephant, it's going to be hard for us to cooperate", Obama said. Obama's remarks come a day after Trump's much-criticised news conference in Helsinki, Finland, in which the USA leader sided with Russian President Vladimir Putin over his own country's intelligence agencies on whether Russia interfered in the U.S. elections in 2016. If you start (by) saying it is an elaborate hoax. where do we start?
"Even when the odds are long and the times are dark, change is always possible".
Instead of commenting on politics, Obama's speech drew on broader themes and his admiration for Mandela, whom America's first black president saw as a mentor.
"People just make stuff up", he said. "When leaders are caught in a lie, they just double down and lie some more".
Former US President Barack Obama speaks during the 2018 Nelson Mandela Annual Lecture in Johannesburg. —AFP
Some of Obama's language echoed that of Trump's critics. Some key indicators of this are the attacks on the free press and the use of social media to promote "hatred, paranoia and propaganda". And the slogan is, "be the legacy of Mandela", now we have a challenge of translating that into practical action so that it doesn't just remain a slogan.
Both Aishwarya and Big B dug out pieces of throwback gold from their archives to pay a heart-felt tribute to the icon - while Ash shared a blast from the past from what appears to be the Miss World competition in 1994, Big B shared a photo which Nelson Mandela had signed for him.
In 2015, Prince Harry visited the archives at the Nelson Mandela Foundation Centre of Memory in Johannesburg, South Africa.
After 27 years in prison in South Africa, Mr Mandela was released in 1990 and became the country's first black president four years later. "And I believe that a world governed by such principles is possible and that it can achieve more peace and more cooperation and pursuit of a common good". "This will be a globally minded speech, highlighting global trends and focusing on how, in his life, Mandela embodied perseverance". Attendees from more than 40 countries will participate in a five-day workshop emphasizing leadership development.
"Growing up and living most of my life under a dictatorship, we were not able to experience this feeling of democracy that South Africans have", Nyoni said.