IV. The interest of the plot generally turns on either love or death, and generally hinges on a single action or episode. When we come to speak of the _best_ subjects of dramatic writing, we are really approaching the domain of treatment, which is much wider and better defined. There it becomes a question for judgment and discretion, and much more certainty can be attained. Instead of considering all dramas, we narrow our search to the best only, judging them by the simple tests of success and frequency of acting, and finding what sort of subjects have been taken, and how they have been treated. Let us then come at once to the question, What is the best method of treating a given subject? Here we are again confronted by a variety of decisions, some of which seem to conflict with others, but which all agree in some common particulars. In the dramas written, down to the time of Boucicault, it seemed to be assumed as a matter of course that every first-class play, comedy or tragedy, must be written in five acts. All of Shakespeare's, Sheridan's, Knowles's, follow this old rule, as inflexible and artificial as some of the French canons, but with the same compensating advantage, that author and audience knew what was expected of each, and troubled themselves little over the structure of their dramas. Of late years another custom has taken the place of the five-act play, and many if not most of the modern dramas, while of the same length as the old ones, are divided into four and even three acts. Especially is this the case with comedies, and those nondescript plays that are variously called "melodramas," "dramas," and "domestic dramas." In the case of three-act plays, the number of scenes in each act is frequently five, sometimes six or seven, but the common modern practice restricts the last act, if possible, to a single scene. The number of scenes must of course depend on how many are absolutely necessary to develop the story. The French system of a single scene to each act has one great advantage. It permits of very much finer scenery being introduced than in a scene which is to be shifted, whether closed in or drawn aside. For instance, when the curtain comes down between each scene, the stage may be crowded with furniture, and those temporary erections called "set pieces." There will always be plenty of time to remove these between the acts, and noise of hammering is of no consequence when the curtain is down. If there is more than one scene in the act, all this is changed. Let us say there are only two scenes. One of these must be a full-depth scene, but all the furniture and set pieces are restricted to that part of the stage which lies behind the two "flats" which make the front scene. In that front scene furniture is inadmissible, without rudely disturbing the illusion. Let us suppose the front scene to be the first, and that any furniture is left on the stage. At the close of the scene the characters leave the stage, but