We have now, it seems, arrived at one consideration, which must always limit the liberty of frankness, namely, the standard of contemporary taste. The modesty that hesitates to align itself with that standard is a shortcoming, the audacity that rushes beyond is a violence to the unchanging law of literature. But the single consideration is insufficient. If we are content with the criterion of contemporary taste alone, our standard of judgment becomes purely historical: we are left, so to speak, with a sliding scale which readjusts itself to every new epoch: we have no permanent and universal test to apply to the literature of different ages: in a word, comparative criticism is impossible. We feel at once that we need, besides the shifting standard of contemporary taste, some fixed unit of judgment that never varies, some foot-rule that applies with equal infallibility to the literature of early Greece and to the literature of later France; and such an unit, such a foot-rule, can only be found in the final test of all art, the necessity of the moral idea. We must, in distinguishing the thing that may be said fairly and artistically from the thing whose utterance is inadmissible, we must in such a decision control our judgment by two standards--the one, the shifting standard of contemporary taste: the other, the permanent standard of artistic justification, the presence of the moral idea. With these two elements in action, we ought, I think, to be able to estimate with tolerable fairness the amount of reticence in any age which ceases to be a shortcoming, the amount of frankness which begins to be a violence in the literature of the period. We ought, with these two elements in motion, to be able to employ a scheme of comparative criticism which will prevent us from encouraging that retarding and dangerous doctrine that what was expedient and justifiable, for instance, in the dramatists of the Restoration is expedient and justifiable in the playwrights of our own Victorian era; we ought, too, to be able to arrive instinctively at a sense of the limits of art, and to appreciate the point at which frankness becomes a violence, in that it has degenerated into mere brawling, animated neither by purpose nor idea. Let us, then, consider these two standards of taste and art separately: and first, let us give a brief attention to the contemporary standard.