(b) Double-Action is Dangerous to Unity.  If you have a scene in which two minor characters come together for a reason vital to the plot, you must be extremely careful not to tell anything more than the facts that are vital.  In long plays the use of what is called “double-action “—­that is, giving to characters necessary to the plot an interest and a destiny separate from that of the chief characters—­is, of course, recognized and productive of fine results.  But, even in the five-act play, the use of double-action is dangerous.  For instance:  Shakespere developed Falstaff so humorously that today we sometimes carelessly think of “Henry IV” as a delightful comedy, when in reality it was designed as a serious drama—­and is most serious, when Falstaff’s lines are cut from the reading version to the right proportions for to-day’s stage effect.  If Shakespere nodded, it is a nod even the legitimate dramatist of today should take to heart, and the playlet writer—­peculiarly restricted as to time—­must engrave deeply in his memory.

The only way to secure unity of action is to concentrate upon your problem or theme; to realize that you are telling a story; to remember that each character, even your hero, is only a pawn to advance the story; and to cut away rigorously all non-essential events.  If you will bear in mind that a playlet is only as good as its plot, that a plot is a story and that you must give to your story, as has been said, “A completeness—­a kind of universal dovetailedness, a sort of general oneness,” you will have little difficulty in observing the one playlet rule that should never be broken—­Unity of action.

2.  Unity of Time

The second of the classical unities, unity of time, is peculiarly perplexing, if you study to “understand” and not merely to write.  Briefly—­for I must reiterate that our purpose is practice and not theory—­the dramatists of every age since Aristotle have quarreled over the never-to-be-settled problem of what space of time a play should be permitted to represent.  Those who take the stand that no play should be allowed to show an action that would require more than twenty-four hours for the occurrences in real life, base their premise on the imitative quality of the stage, rather than upon the selective quality of art.  While those who contend that a play may disregard the classical unity of time, if only it preserves the unity of action, base their contention upon the fact that an audience is interested not in time at all—­but in story.  In other words, a play preserves the only unity worth preserving when it deals with the incidents that cause a crisis and ends by showing its effect, no matter whether the action takes story-years to occur or happens all in a story-hour.

If we were studying the long drama it might be worth our while to consider the various angles of this ancient dispute, but, fortunately, we have a practical and, therefore, better standard by which to state this unity in its application to the playlet.  Let us approach the matter in this way: