Acts, then, mark the time-stages in the development of a given crisis; and each act ought to embody a minor crisis of its own, with a culmination and a temporary solution.  It would be no gain, but a loss, if a whole two hours’ or three hours’ action could be carried through in one continuous movement, with no relaxation of the strain upon the attention of the audience, and without a single point at which the spectator might review what was past and anticipate what was to come.  The act-division positively enhances the amount of pleasurable emotion through which the audience passes.  Each act ought to stimulate and temporarily satisfy an interest of its own, while definitely advancing the main action.  The psychological principle is evident enough; namely, that there is more sensation to be got out of three or four comparatively brief experiences, suited to our powers of perception, than out of one protracted experience, forced on us without relief, without contrast, in such a way as to fatigue and deaden our faculties.  Who would not rather drink three, four, or five glasses of wine than put the bottle to his lips and let its contents pour down his throat in one long draught?  Who would not rather see a stained-glass window broken into three, four, or five cunningly-proportioned “lights,” than a great flat sheet of coloured glass, be its design never so effective?

It used to be the fashion in mid Victorian melodramas to give each act a more or less alluring title of its own.  I am far from recommending the revival of this practice; but it might be no bad plan for a beginner, in sketching out a play, to have in his mind, or in his private notes, a descriptive head-line for each act, thereby assuring himself that each had a character of its own, and at the same time contributed its due share to the advancement of the whole design.  Let us apply this principle to a Shakespearean play—­for example, to Macbeth.  The act headings might run somewhat as follows—­

  ACT I.—­TEMPTATION.

  ACT II.—­MURDER AND USURPATION.

  ACT III.—­THE FRENZY OF CRIME AND THE HAUNTING OF REMORSE.

  ACT IV.—­GATHERING RETRIBUTION.

  ACT V.—­RETRIBUTION CONSUMMATED.

Can it be doubted that Shakespeare had in his mind the rhythm marked by this act-division?  I do not mean, of course, that these phrases, or anything like them, were present to his consciousness, but merely that he “thought in acts,” and mentally assigned to each act its definite share in the development of the crisis.

Turning now to Ibsen, let us draw up an act-scheme for the simplest and most straightforward of his plays, An Enemy of the People.  It might run as follows: 

  ACT I.—­THE INCURABLE OPTIMIST.—­Dr. Stockmann announces his
  discovery of the insanitary condition of the Baths.