Of course, when Mr. Shaw protests that, in Getting Married, he did not indulge in a “deliberate display of virtuosity of form,” that is only his fun. You cannot well have virtuosity of form where there is no form. What he did was to rely upon his virtuosity of dialogue to enable him to dispense with form. Whether he succeeded or not is a matter of opinion which does not at present concern us. The point to be noted is the essential difference between the formless continuity of Getting Married, and the sedulous ordering and balancing of clearly differentiated parts, which went to the structure of a Greek tragedy. A dramatist who can so develop his story as to bring it within the quasi-Aristotelean “unities” performs a curious but not particularly difficult or valuable feat; but this does not, or ought not to, imply the abandonment of the act-division, which is no mere convention, but a valuable means of marking the rhythm of the story. When, on the other hand, you have no story to tell, the act-division is manifestly superfluous; but it needs no “virtuosity” to dispense with it.
It is a grave error, then, to suppose that the act is a mere division of convenience, imposed by the limited power of attention of the human mind, or by the need of the human body for occasional refreshment. A play with a well-marked, well-balanced act-structure is a higher artistic organism than a play with no act-structure, just as a vertebrate animal is higher than a mollusc. In every crisis of real life (unless it be so short as to be a mere incident) there is a rhythm of rise, progress, culmination and solution. We are not always, perhaps not often, conscious of these stages; but that is only because we do not reflect upon our experiences while they are passing, or map them out in memory when they are past. We do, however, constantly apply to real-life crises expressions borrowed more or less directly from the terminology of the drama. We say, somewhat incorrectly, “Things have come to a climax,” meaning thereby a culmination; or we say, “The catastrophe is at hand,” or, again, “What a fortunate denouement!” Be this as it may, it is the business of the dramatist to analyse the crises with which he deals, and to present them to us in their rhythm of growth, culmination, solution. To this end the act-division is—not, perhaps, essential, since the rhythm may be marked even in a one-act play—but certainly of enormous and invaluable convenience. “Si l’acte n’existait pas, il faudrait l’inventer”; but as a matter of fact it has existed wherever, in the Western world, the drama has developed beyond its rudest beginnings.