Graça Machel, DBE (born Graça Simbine; 17 October 1945) is a Mozambican politician, humanitarian and international advocate for women’s and children’s rights.

She was the third wife and now the widow of former South African president Nelson Mandela, as well as the widow of the late Mozambican president Samora Machel.

She is the only woman in the world to have served as the First Lady of two different nations.

Margaret Heffernan is an entrepreneur, Chief Executive and author. She was born in Texas, raised in Holland and educated at Cambridge University.

She worked in BBC Radio for five years where she wrote, directed, produced and commissioned dozens of documentaries and dramas.

Here are 14 provocative quotes from her TEDGlobal 2012 talk: