5. This argument, I think, is in many instances unfounded. Eratosthenes availed himself of the statements of many writers, although Hipparchus alleges he was solely led by Patrocles. Who then are the authors of the statement that the southern extremity of India is under the same parallel as Meroe; and who are they who estimate[487] the distance from Meroe to the parallel passing through Athens? Or who, again, were those who asserted that the whole breadth occupied by the mountains[488] was equal to the distance from Cilicia to Amisus? Or who made known that, travelling from Amisus, the course lay in a straight line due east through Colchis, the [sea of] Hyrcania, so on to Bactria, and beyond this to the eastern ocean,[489] the mountains being always on the right hand; and that this same line carried west in a straight line, traverses the Propontis and the Hellespont? These things Eratosthenes advances on the testimony of men who had been on the spot, and from the study of those numerous memoirs which he had for reference in that noble library[490] which Hipparchus himself acknowledges to be gigantic. 6. Besides, the credibility of Patrocles can be proved by a variety of evidence—the princes[491] who confided to him so important trusts—the authors who follow his statements—and those, too, who criticise them, whose names Hipparchus has recorded. Since whenever these are refuted, the credit of Patrocles is by so much advanced. Nor does Patrocles appear to state any thing improbable when he says that the army of Alexander took but a very hasty view of every thing [in India], but Alexander himself a more exact one, causing the whole country to be described by men well acquainted with it. Which description he says was afterwards put into his hands by Xenocles the treasurer. 7. Again, in the second volume of his Commentaries, Hipparchus accuses Eratosthenes of himself throwing discredit on the statement of Patrocles, on account of his differing with Megasthenes, as to the length of India on its northern side;[492] Megasthenes stating the length at 16,000 stadia, and Patrocles at 1000 less. Being biased by a certain Itinerary, Eratosthenes was led to reject them both on account of this discrepancy, and to follow the Itinerary. If then merely the difference of 1000 stadia is sufficient to cause the authority of Patrocles to be rejected, how much more should this be the case when we find a difference of 8000 stadia between his statement and that of two writers who agree perfectly in theirs, that the breadth of India is 20,000 stadia, while he gives only 12,000!