But enough of this. For I have written again and again for your encouragement. Let us now return to the remaining section of our subject as outlined. #Panaetius on Moral Duties.# *7* Panaetius, then, has given us what is unquestionably the most thorough discussion of moral duties that we have, and I have followed him in the main--but with slight modifications. He classifies under three general heads the ethical problems which people are accustomed to consider and weigh: first, the question whether the matter in hand is morally right or morally wrong; second, whether it is expedient or inexpedient; third, how a decision ought to be reached, in case that which has the appearance of being morally right clashes with that which seems to be expedient. He has treated the first two heads at length in three books; but while he has stated that he meant to discuss the third head in its proper turn, he has never fulfilled his promise. *8* And I wonder the more at this, because Posidonius, a pupil of his, records that Panaetius was still alive thirty years after he published those three books. And I am surprised that Posidonius has but briefly touched upon this subject in certain memoirs of his, and especially, as he states that there is no other topic in the whole range of philosophy so essentially important as this. #Why Panaetius omitted the "Conflict" of the moral and the expedient.# *9* Now, I cannot possibly accept the view of those who say that that point was not overlooked but purposely omitted by Panaetius, and that it was not one that ever needed discussion, because there never can be such a thing as a conflict between expediency and moral rectitude. But with regard to this assertion, the one point may admit of doubt--whether that question which is third in Panaetius's classification ought to have been included or omitted altogether; but the other point is not open to debate--that it was included in Panaetius's plan but left unwritten. For if a writer has finished two divisions of a threefold subject, the third must necessarily remain for him to do. Besides, he promises at the close of the third book that he will discuss this division also in its proper turn. *10* We have also in Posidonius a competent witness to the fact. He writes in one of his letters that Publius Rutilius Rufus, who also was a pupil of Panaetius's, used to say that "as no painter had been found to complete that part of the Venus of Cos which Apelles had left unfinished (for the beauty of her face made hopeless any attempt adequately to represent the rest of the figure), so no one, because of the surpassing excellence of what Panaetius did complete, would venture to supply what he had left undone."