tyche
The paradoxes of fortune, that is, rapid changes in human circumstances, whose particular components can be rationally explained, but whose cumulative effect is unpredictable and awe-inspiring. Most strikingly, he states that the rise of Rome to world-domination was directed by tyche, though he argues elsewhere that chance played no part in Roman success, but it was to be expected in the light of their power, political stability, and enterprise. (Boardman, 1986)