The first act may be regarded as the porch or vestibule through which we pass into the main fabric—­solemn or joyous, fantastic or austere—­of the actual drama.  Sometimes, indeed, the vestibule is reduced to a mere threshold which can be crossed in two strides; but normally the first act, or at any rate the greater part of it, is of an introductory character.  Let us conceive, then, that we have passed the vestibule, and are now to study the principles on which the body of the structure is reared.

In the first place, is the architectural metaphor a just one?  Is there, or ought there to be, any analogy between a drama and a finely-proportioned building?  The question has already been touched on in the opening paragraphs of Chapter VIII; but we may now look into it a little more closely.

What is the characteristic of a fine piece of architecture?  Manifestly an organic relation, a carefully-planned interdependence, between all its parts.  A great building is a complete and rounded whole, just like a living organism.  It is informed by an inner law of harmony and proportion, and cannot be run up at haphazard, with no definite and pre-determined design.  Can we say the same of a great play?

I think we can.  Even in those plays which present a picture rather than an action, we ought to recognize a principle of selection, proportion, composition, which, if not absolutely organic, is at any rate the reverse of haphazard.  We may not always be able to define the principle, to put it clearly in words; but if we feel that the author has been guided by no principle, that he has proceeded on mere hand-to-mouth caprice, that there is no “inner law of harmony and proportion” in his work, then we instinctively relegate it to a low place in our esteem.  Hauptmann’s Weavers certainly cannot be called a piece of dramatic architecture, like Rosmersholm or Iris; but that does not mean that it is a mere rambling series of tableaux.  It is not easy to define the principle of unity in that brilliant comedy The Madras House; but we nevertheless feel that a principle of unity exists; or, if we do not, so much the worse for the play and its author.

There is, indeed, a large class of plays, often popular, and sometimes meritorious, in relation to which the architectural metaphor entirely breaks down.  They are what may be called “running fire” plays.  We have all seen children setting a number of wooden blocks on end, at equal intervals, and then tilting over the first so that it falls against the second, which in turn falls against the third, and so on, till the whole row, with a rapid clack-clack-clack, lies flat upon the table.  This is called a “running fire”; and this is the structural principle of a good many plays.  We feel that the playwright is, so to speak, inventing as he goes along—­that the action, like the child’s fantastic serpentine of blocks, might at any moment take a turn in any possible direction without falsifying its antecedents or our expectations.  No part of it is necessarily involved in any other part.  If the play were found too long or too short, an act might be cut out or written in without necessitating any considerable readjustments in the other acts.  The play is really a series of episodes,