A few years back I worked with a man from South Africa who told stories about the years after the end of the old regime in South Africa. We, his colleagues, just had to ask him at one point why, in heaven's name, he stayed. He wasn't an overtly racist fellow by any means but when he talked about the years of fear and uncertainty, I think we all had to wonder if we would have done the same thing under those circumstances. He did it for his country, he said. He had hope that things could be better and the new government had a vision he could follow. Recreating South Africa was presented to him as a national project and it moved him to stay and serve.
That I would say is the sign of a great leader. It's not what he or she does so much as what he can inspire others to do. Here are Mandela's words from his inaugural speech back in 1994:
"We understand it still that there is no easy road to freedom.
We know it well that none of us acting alone can achieve success.
We must therefore act together as a united people, for national reconciliation, for nation building, for the birth of a new world."
Anima eius et animae omnium fidelium defunctorum per Dei misericordiam requiescant in pace
(May his soul, and the souls of all the dead faithful by God's mercy, rest in peace.)