We derive Aristotle’s philosophy from his writings; but when we consider their history and nature, so far as externals are concerned, the difficulty of deriving a knowledge of his philosophy from them seems much increased. I cannot certainly enter into details regarding these last. Diogenes Laërtius (V. 21-27) mentions a very large number of them, but by their titles we do not always quite know which of those now in our possession are indicated, since the titles are entirely different. Diogenes gives the number of lines as four hundred and forty-five thousand, two hundred and seventy, and, if we count about ten thousand lines in a printer’s alphabet, this gives us forty-four alphabets. What we now have might perhaps amount to about ten alphabets, so that we have only about the fourth part left to us. The history of the Aristotelian manuscripts has been stated to be such that it would really seem impossible, or almost hopeless, that any one of his writings should have been preserved to us in its original condition, and not corrupted. Doubts regarding their genuine character could not in such circumstances fail to exist; and we can only wonder at seeing them come down to us even in the condition in which they are. For, as we have said, Aristotle made them known but little during his lifetime, and he left his writings to Theophrastus, his successor, with the rest of his immense library. This, indeed, is the first considerable library, collected as it was by means of personal wealth along with Alexander’s assistance, and hence it also reveals to us Aristotle’s learning. Later on, it came partially, or in some cases in duplicate, to Alexandria, and formed the basis of the Ptolemaic library, which, on the taking of Alexandria by Julius Cæsar, became a prey to fire. But of the manuscripts of Aristotle himself it is said that Theophrastus left them by will to a certain Neleus, from whom they came into the hands of ignorant men, who either kept them without care or estimation of their value, or else the heirs of Neleus, in order to save them from the Kings of Pergamus, who were very anxious to collect a library, hid them in a cellar, where they lay forgotten for a hundred and thirty years, and thus got into bad condition. Finally, the descendants of Theophrastus found them again after long search, and sold them to Apellicon of Teos, who restored what had been destroyed by worms and mould, but who did not possess the learning or the capacity so to do. Hence others went over them, filled up the blanks as they thought best, replaced what was damaged, and thus they were sufficiently altered. But still it was not enough. Just after Apellicon’s death, the Roman Sulla conquered Athens, and amongst the spoil carried off to Rome were the works of Aristotle. The Romans, who had just begun to become acquainted with Greek science and art, but who did not yet appreciate Greek philosophy, did not know how to profit from this spoil.