“According to Apollodorus, we have accounted fourscore years from the Trojan War to the return of Heraclides: from thence to the first olympiad, three hundred and twenty-eight years, computing the times from the Lacedæmonian kings: from the first olympiad to the beginning of the Gallic War (where our history ends) are seven hundred and thirty years: so that our whole work (comprehended in forty books) is an history which takes in the affairs of eleven hundred and thirty-eight years, besides those times that preceded the Trojan War.” In his preface Diodorus further explains the exact scope of his work and the precise division in the books in the following words: “Our first six books comprehend the affairs and mythologies of the ages before the Trojan War, of which the three first contain the barbarian, and the next following almost all the Grecian antiquities. In the eleven next after these, we have given an account of what has been done in every place from the time of the Trojan War till the death of Alexander. In the three and twenty books following, we have set forth all other things and affairs, till the beginning of the war the Romans made upon the Gauls; at which time Julius Cæsar, the emperor (who upon the account of his great achievements was surnamed Divus), having subdued the warlike nations of the Gauls, enlarged the Roman Empire, as far as to the British Isles; whose first acts fall in with the first year of the hundred and eightieth olympiad, when Herodes was chief magistrate at Athens. But as to the limitations of times contained in the work, we have not bound those things that happened before the Trojan War within any certain limits, because we could not find any foundation whereon to rely with any certainty.” Of these forty books only fifteen have come down to us intact, namely, the first five, which carry down the history only to the Trojan wars, and books eleven to twenty, which cover the period from the invasion of Greece by Xerxes to the subjugation of Greece by the Romans. The remaining books are represented by considerable fragments, which, however, even in the aggregate, are insignificant in bulk as compared with the fifteen books that are preserved entire.