It is hard to persuade the students of a past generation that the historic mode of approaching any problem is the first step toward its successful solution. Yet a little reflection may at least make the meaning of the assertion understood. If we view the literary characteristic of the present, in comparison with that of past ages, we are perhaps right in stating, that its peculiar feature is the prevalence of the method of historical criticism. If the four centuries since the Renaissance be considered, the critical peculiarity of the sixteenth and seventeenth will be found to be the investigation of ancient literature; in the former directed to _words_, in the latter to _things_. The eighteenth century broke away from the past, and, emancipating itself from authority, tried to rebuild truth from its foundations from present materials, independent of the judgment formed by past ages. The nineteenth century unites both methods. It ventures not to explore the universe, unguided by the experience of the past; but, while reuniting itself to the past, it does not bow to it. It accepts it as a fact, not as an authority. The seventeenth century worshipped the past; the eighteenth despised it: the nineteenth mediates, by means of criticism. Accordingly, in literary investigations at present, each question is approached from the historic side, with the belief that the historico-critical inquiry not only gratifies curiosity, but actually contributes to the solution of the problem. Some indeed assert(21) this, because they think that the historic study of philosophy is the whole of philosophy; and, believing that all truth is relative to its age, are hopeless of attaining the absolute and unaltering solution of any problem. We, on the other hand, are content to believe that the history of philosophy is only the entrance to philosophy. But in either case, truth is sought by means of a philosophical history of the past; which, tracking the progress of truth and error in any particular department, lays bare the natural as well as the literary history; the causes of the past, as well as its form. Truth and error are thus discovered, not by breaking with the past, and using abstract speculations on original data, but by tracing the growth of thought, gathering the harvest of past investigations, and learning by experience to escape error. These considerations bear upon the present subject in this manner: they show not only the special adaptation to the passing tastes of the age, of an historic mode of approaching a subject, but exhibit also that the mode of proof and of refutation must be sought, not on abstract grounds, but historic. The position of an enemy is not to be forced, but turned; his premises to be refuted, not his conclusions; the antecedent reasons which led him into his opinion to be exhibited, not merely evidence offered of the fact that he is in error.