There remained the prejudice of considering the ancient historians as best informed about primitive times: whereas in the history of origins they knew as little as, or less than, ourselves. As for Greek history, Vico found, or rather imagined that he found, in Thucydides, a confession that the Greeks up to the generation preceding that historian knew nothing of their own antiquity: and he also observed that it was only in the time of Xenophon that Greek historians began to have any precise information upon Persian affairs. Roman historians commonly began with the foundation of Rome: but the beginning of Rome was certainly not the beginning of the world. Rome was a new city founded in the midst of a large number of small and more ancient peoples in Latium: and even in the case of Rome Livy refuses to guarantee the truth of the facts of the earlier centuries of its history up to the Punic wars, which he is in a position to describe more accurately. He even confesses frankly that he does not know at what point Hannibal made his great and memorable entry into Italy, whether by the Cottian Alps or the Apennines. So well informed were the ancient historians! Owing to these and similar sceptical principles, the whole of Greek history to the time of Herodotus and of Roman down to the second Punic war seemed to Vico quite uncertain, an unclaimed territory, so to speak, where one might enter and take possession by squatter's right. He entered armed with positive principles directly issuing from the negative ones we have enumerated. For if Vico denied the credibility of historians distant in time from the facts they described, if he discounted national pride, if he laid bare the illusions and charlatanism of the learned, he nevertheless did not rest content with this work of destruction. In place of the old untrustworthy method he had banished, he endeavoured to supply a new, of better qualities and greater tenacity; a system of methods by which it was possible to acquire new historical documents and also to improve the study of those already known. No advance in historical knowledge is in fact ever made except by thus turning from the received narrative to the document underlying it, which alone has the power of confirming, correcting and enriching the narrative.