A good leader is one who can tell another how to reach his or her potential; a great leader is one who can help another discover this potential for him or herself. ↗
A good leader can engage in a debate frankly and thoroughly, knowing that at the end he and the other side must be closer, and thus emerge stronger. You don't have that idea when you are arrogant, superficial, and uninformed. ↗
Leadership is hard to define and good leadership even harder. But if you can get people to follow you to the ends of the earth, you are a great leader. ↗