Every historian has some attitude toward the speed and direction of human development, and this is the historian's concept of time. Historians should not be seduced by abstract chronology into assuming that time flows evenly; their task is to discern the swiftness or slowness, the advance or retrogression of the movement of events. The alleged difference between the "unhistorical" Greek conception of cyclical time and the "historical" Christian conception of linear time is not supported by the evidence from Greek and Christian historiography; it reflects a confusion between what philosophers have said about time and what historians in all ages have meant.