In the course of this perennial discussion we constantly meet with appeals, on the part of those learned gentlemen, the theatrical critics, to the "dramatic canons." Such and such a play is said to offend against these "canons," and they are spoken of as something of which it is shameful to be ignorant, but at the same time with a vagueness of phrase betraying a similar vagueness of definition. It has seemed to us that an inquiry into the nature of these canons may not be out of place at the present time. This we propose to determine by consulting the practice of those authors of former times whose productions still hold the stage as "stock plays," so called, and of those modern authors still living whose plays are well known and famous, being still successfully acted. By such an analysis we may possibly settle something, especially if our inquiry shall call forth the actual experience of those living who have attained great success, whether as authors or adapters. The most obvious division of our subject is into tragedy, comedy, melodrama; but inasmuch as it is plain that the laws of success in all these walks of dramatic art must contain much in common, we have preferred a different division for analysis, leaving the kind of drama as a subdivision common to each part of the inquiry. A less obvious but equally just division will be as to the canons regulating the subject, the treatment, and the production of a successful drama, in whatever walk. We propose to ascertain our canons from the successful plays, still holding the stage, of Shakespeare, Sheridan, Knowles, Bulwer, Dion Boucicault, Tom Taylor, Augustin Daly, and Gilbert, together with such single plays, like "The Honeymoon," "Masks and Faces," and a few others, as are better known to the public than their authors, whose sole dramatic successes they were. Ephemeral successes, however great, cannot be safely taken as guides to a canon; but an established success of long standing, however repugnant to our tastes, must be examined, even if it take the form of the "Black Crook." The influence of the French drama on Anglo-Saxon art has been so decided that no safe estimates of canons can be made which do not take into account the works of Sardou, Dumas, and the minor French authors, whose name is legion. Fortunately for our subject, the French work on simple principles, and will not confuse us any more than the Greeks, whom they imitate. Let us try, then, to ascertain our canons in their order, beginning with the subject of the drama. What subjects are fit for dramatic treatment, and are there any entirely unfitted therefor?