H i s t o r y is action based upon knowledge. But the action which is history is circumscribed, and limited to the accurate telling o f an important and necessary story. The historian is a social agent. His discipline differs from the other branches o f the humanities and from the sciences o f nature. Among intellectual workers the historian is peculiarly situated: the methodological, ethical and social problems that face him do not arise-or not in the same way-in the exercise o f other intellectual activities. These problems are mainly concerned, not with the events that appear in his story, but with the generalizations, explanations, and other elements that belong to it, and with the various modes o f serialization to which the events must be submitted.