Notwithstanding all the obstructions and discouragements in the way of this investigation a few great men have given it a certain amount of attention. Aristotle informs us in his "Rhetoric" that he has dealt fully with the subject in his Poetics, and although the treatise is unfortunately lost, some annotations remain which show that it was of a comprehensive character. Cicero and Quintilian in their instructions in Oratory, made the study of humour a necessary part of the course, and in modern days many ingenious definitions and descriptions of it are found among the pages of general literature. Most philosophers have touched the subject timidly and partially, unwilling to devote much time to it, and have rather stated what they thought ought to be in accordance with some pet theories of their own, than drawn deductions from careful analysis. They generally only looked at one phase of the ludicrous, at one kind of humour, and had not a sufficient number of examples before them--probably from the difficulty of recalling slight turns of thought in widely scattered subjects. Add to this, that many of them--constantly immersed in study--would have had some little difficulty in deciding what did and did not deserve the name of humour. Most of their definitions are far too wide, and often in supporting a theory they make remarks which tend to refute it. The imperfect treatment, which the subject had received, led Dugald Stewart to observe that it was far from being exhausted. The two principal publications which have appeared on humour, are Floegel's "Geschichte der Komischen Litteratur" (1786), and Leon Dumont's "Les Causes du Rire." The former is voluminous, but scarcely touches on philosophy, without which such a work can have but little coherence. The latter shows considerable psychological knowledge, but is written to support a somewhat narrow and incomplete view. Mr. Wright's excellent book on "The Grotesque in Literature and Art," is, as the name suggests, principally concerned with broad humour, and does not so much trace its source as the effects it has produced upon mankind. Mr. Cowden Clark's contributions on the subject to the "Gentleman's Magazine," are mostly interesting from their biographical notices.