Writing about heroic leaders in the African Valhalla, the late Professor Ivan Van Sertima wrote that when a star dies it does not vanish from the firmament. Its light keeps streaming across the fields of time and space so that centuries later we may be touched by a vision of the fire and brilliancy of its former life. The lives of the truly great are just like that. Death does not diminish them in the firmament of our consciousness, where their words and deeds still twinkle like the lights of long-dead stars. But we are touched by these lights in different ways in different times and it is not always easy for the observer to distinguish the startling flash of a transitory meteor from the paler, ghostly light of a grander and greater star.