Nelson Mandela also spoke about how, as a human being, he's made mistakes.

You know how they say, 'What happens in Vegas, stays in Vegas?' What happens in the Arctic doesn't stay in the Arctic.

Struggles only move forward when decent men and women step forward and say, 'enough is enough and no more.'

My final advice for young people is to not wait for leadership from adult politicians. Step forward today, because our current leaders are denying the dire reality we are facing. Leadership can come form anywhere.

I was 15 years old when I first heard the name Mandela, or Madiba, as he is fondly known in Africa. In apartheid South Africa he was public enemy number one. Shrouded in secrecy, myth and rumour, the media called him 'The Black Pimpernel'.

[Nelson] Mandela was very keen not to be understood as an exceptional person.

Sandy was a climate change warning. Obama must now take the stage and fulfil the promise of hope the world needs.