our noorch freedom is irreversible. we must not allow fear to stand in our way. >> good morning. i'm melissa harris-perry. the world lost one of its greatest leaders and agents of social change with the passing of nelson mandela at the age of 95 on thursday. madiba, the clan name by which he was known, transcended the boundaries of south africa as it became synonymous with the country's greatest struggles and triumphs. mandela meant many things to many people, including president obama, who offered this tribute shortly after mandela's death. >> for now, let us pause and give thanks for the fact that nelson mandela lived, a man who took history in his hands and bent the arc of the moral universe towards justice. >> no one can deny the indelible contributions and sacrifices