What does Mandela mean when he says he is “simply the sum of all those African patriots” who had gone before him?

When Mandela says that he was ‘simply the sum of all African patriots,’ he means that he could identify with the unimaginable sacrifices of all those noble and courageous men who fought for the collective freedom of the African people. He was pained that he could not thank them and that they could not see what their sacrifices had wrought.