*340D* You argue like an informer, Socrates. Do you mean, for example, that he who is mistaken about the sick is a physician in that he is mistaken? or that he who errs in arithmetic or grammar is an arithmetician or grammarian at the time when he is making the mistake, in respect of the mistake? True, we say that the physician or arithmetician or grammarian has made a mistake, but this is only a way of speaking; for the fact is that neither the grammarian nor any other person of skill ever makes a mistake in so far as he is what his name implies; they none of them err unless their skill fails them, and then they cease to be skilled artists. {18} No artist or sage or ruler errs at the time when he is what his name implies; though he is commonly said to err, and *340E* I adopted the common mode of speaking. But to be perfectly accurate, since you are such a lover of accuracy, we should say that the ruler, in so far as he is a ruler, is unerring, and, *341A* being unerring, always commands that which is for his own interest; and the subject is required to execute his commands; and therefore, as I said at first and now repeat, justice is the interest of the stronger. [Sidenote: Socrates, Thrasymachus.] Indeed, Thrasymachus, and do I really appear to you to argue like an informer? Certainly, he replied. And do you suppose that I ask these questions with any design of injuring you in the argument? Nay, he replied, 'suppose' is not the word--I know it; *341B* but you will be found out, and by sheer force of argument you will never prevail. I shall not make the attempt, my dear man; but to avoid any misunderstanding occurring between us in future, let me ask, in what sense do you speak of a ruler or stronger whose interest, as you were saying, he being the superior, it is just that the inferior should execute--is he a ruler in the popular or in the strict sense of the term? In the strictest of all senses, he said. And now cheat and play the informer if you can; I ask no quarter at your hands. But you never will be able, never. [Sidenote: The essential meaning of words distinguished from their attributes.] *341C* And do you imagine, I said, that I am such a madman as to try and cheat, Thrasymachus? I might as well shave a lion. Why, he said, you made the attempt a minute ago, and you failed. Enough, I said, of these civilities. It will be better that I should ask you a question: Is the physician, taken in that strict sense of which you are speaking, a healer of the sick or a maker of money? And remember that I am now speaking of the true physician. A healer of the sick, he replied. And the pilot--that is to say, the true pilot--is he a captain of sailors or a mere sailor? A captain of sailors. {19}