Preface. THE aim of the present Essay is to embody in a united whole the laws and principles of literature in its most general relations. It is now sixteen years since the Essay was first presented to the public. In the kind reception then accorded the book by critics of nearly every shade of opinion, the Author has found encouragement to prepare this new edition. It runs upon the same lines of thought as the old edition. Parts have been revised, parts developed, and parts re-written, in the hope that the work will be found every way less unworthy of the subject. There is one remark of an esteemed Reviewer upon which the Author would dwell. The late Dr. Orestes A. Brownson wrote, among many other complimentary things, upon the first appearance of the book: "We have been struck with the depth and justness of the Author's philosophical principles, which could, as we understand them, be borrowed from no school of philosophy generally accepted by Catholics or by non-catholics" (Brownson's Review, Oct., 1874, p. 561). Every earnest thinker must begin by breaking through the shackles of schools and systems. Philosophy is above schools and systems. None knew better than the great Brownson that he who commits himself to any school of thought -- any exclusive System -- thereby so narrows the horizon of his intellectual vision, that he no longer sees things in themselves, but merely certain imperfect aspects of things. The primary and self evident truths of our reason, from which start all philosophy and all knowledge, are not of this school or that; they simply are. Every teacher of literature, be the literature home or foreign, will perceive the benefit of placing his pupils upon this elevated vantage~ground from which to survey the various great authors and take their relative bearings.