'Did none of us before you talk of "good" or "just," or did we use the terms vaguely and idly without understanding what each of them meant?' Who told you, Theopompus, that we had not natural notions and primary conceptions of each of these? But it is impossible to adjust the primary conceptions to the appropriate facts, without making them articulate and without considering just this—what fact must be ranged under each conception. You may say just the same thing, for instance, to physicians. Which of us did not use the words 'healthy' and 'diseased' before Hippocrates was born? Were those terms we used mere empty sounds? No, we have a conception of 'healthy', but we cannot apply it. Therefore one physician says, 'Take no food', and another 'Give food', and one says, 'Cut the vein', and another, 'Use the cupping-glass.' What is the reason? Nothing but incapacity to apply the conception of 'the healthy' to particulars in the proper way.
Plain English · paraphrase"Did none of us before you talk about 'good' or 'just,' or did we use those terms vaguely and carelessly without understanding what each meant?" Who told you, Theopompus, that we didn't have natural ideas and basic understandings of each of these? But it's impossible to match those basic ideas with the right facts without making them clear and without considering exactly what facts belong under each idea. You could say the same thing, for example, to physicians. Which of us didn't use the words 'healthy' and 'diseased' before Hippocrates was born? Were those terms we used just empty sounds? No, we have an idea of 'healthy,' but we can't apply it. Therefore, one physician says, "Take no food," and another says, "Give food," and one says, "Cut the vein," and another says, "Use the cupping-glass." What is the reason? Nothing but the inability to apply the idea of 'the healthy' to particular cases in the right way."