SOCRATES: Tell me then, what Nestor says to Antilochus, his son, where he bids him be careful of the turn at the horserace in honour of Patroclus. ION: 'Bend gently,' he says, 'in the polished chariot to the left of them, and urge the horse on the right hand with whip and voice; and slacken the rein. And when you are at the goal, let the left horse draw near, yet so that the nave of the well-wrought wheel may not even seem to touch the extremity; and avoid catching the stone (Il.).' SOCRATES: Enough. Now, Ion, will the charioteer or the physician be the better judge of the propriety of these lines? ION: The charioteer, clearly. SOCRATES: And will the reason be that this is his art, or will there be any other reason? ION: No, that will be the reason. SOCRATES: And every art is appointed by God to have knowledge of a certain work; for that which we know by the art of the pilot we do not know by the art of medicine? ION: Certainly not. SOCRATES: Nor do we know by the art of the carpenter that which we know by the art of medicine? ION: Certainly not. SOCRATES: And this is true of all the arts;--that which we know with one art we do not know with the other? But let me ask a prior question: You admit that there are differences of arts? ION: Yes. SOCRATES: You would argue, as I should, that when one art is of one kind of knowledge and another of another, they are different? ION: Yes. SOCRATES: Yes, surely; for if the subject of knowledge were the same, there would be no meaning in saying that the arts were different,--if they both gave the same knowledge. For example, I know that here are five fingers, and you know the same. And if I were to ask whether I and you became acquainted with this fact by the help of the same art of arithmetic, you would acknowledge that we did? ION: Yes. SOCRATES: Tell me, then, what I was intending to ask you,--whether this holds universally? Must the same art have the same subject of knowledge, and different arts other subjects of knowledge? ION: That is my opinion, Socrates. SOCRATES: Then he who has no knowledge of a particular art will have no right judgment of the sayings and doings of that art? ION: Very true. SOCRATES: Then which will be a better judge of the lines which you were reciting from Homer, you or the charioteer? ION: The charioteer. SOCRATES: Why, yes, because you are a rhapsode and not a charioteer. ION: Yes. SOCRATES: And the art of the rhapsode is different from that of the charioteer? ION: Yes. SOCRATES: And if a different knowledge, then a knowledge of different matters? ION: True. SOCRATES: You know the passage in which Hecamede, the concubine of Nestor, is described as giving to the wounded Machaon a posset, as he says, 'Made with Pramnian wine; and she grated cheese of goat's milk with a grater of bronze, and at his side placed an onion which gives a relish to drink (Il.).'