But note for a few moments the precise treatment of the idea of Justice in the first book of The Republic. Sophistry and common sense are trying their best to apprehend, to cover or occupy, a certain space, as the exact area of Justice. And what happens with each proposed definition in turn is, that it becomes, under conceivable circumstances, a definition of Injustice: not that, in practice, a confusion between the two is therefore likely; but that the intellect remains unsatisfied of the theoretic validity of the distinction. Now that intellectual situation illustrates the sense in which sophistry is a reproduction of the Heraclitean flux. The old Heraclitean physical theory presents itself as a natural basis for the moral, the social, dissolution, which the sophistical [113] movement promotes. But what a contrast to it, in the treatment of Justice, of the question, What Justice is? in that introductory book of The Republic. The first book forms in truth an eristic, a destructive or negative, Dialogue (such as we have other examples of) in which the whole business might have concluded, prematurely, with an exposure of the inadequacy, alike of common-sense as represented by Simonides, and of a sophisticated philosophy as represented by Thrasymachus, to define Justice. Note, however, in what way, precisely. That it is Just, for instance, to restore what one owes (to ta opheilomena apodidonai)+ might pass well enough for a general guide to right conduct; and the sophistical judgment that Justice is "The interest of the stronger" is not more untrue than the contrary paradox that "Justice is a plot of the weak against the strong." It is, then, in regard to the claims of Justice, not so much on practice, as on the intellect, in its demand for a clear theory of practice, that those definitions fail. They are failures because they fail to distinguish absolutely, ideally, as towards the intellect, what is, from what is not. To Plato, for whom, constitutionally, and ex hypothesi, what can be clearly thought is the precise measure of what really is, if such a thought about Justice--absolutely inclusive and exclusive--is, after all our efforts, not to be ascertained, this can only be, because Justice is not [114] a real thing, but only an empty or confused name.