This essay suggests that the Renaissance revolution in historical thought was encouraged by contemporary debates over the Aristotelian-Averroistic doctrine of the eternity of the world. In the early Renaissance eternalism came to be understood as a proposition with controversial consequences not only for the creation of matter e nihilo but also for the record of historical time. Modern scholarship, following Momigliano, believes that understandings of time had little effect on the practice of ancient historians. But that was not the view of Orosius, the most widely read historian during the Middle Ages, who condemned the pagan historians for their eternalism. Nor was it the view of the Italian humanists who, after reading the Greek historians, abandoned the providentialism of Orosius and revived ancient ways of writing history.