“Which might, odd bobs, sir! in judicious hands,
  Extend from here to Mesopotamy.”

The episodes may grow out of each other plausibly enough, but by no pre-ordained necessity, and with no far-reaching interdependence.  We live, in such plays, from moment to moment, foreseeing nothing, desiring nothing; and though this frame of mind may be mildly agreeable, it involves none of that complexity of sensation with which we contemplate a great piece of architecture, or follow the development of a finely-constructed drama.  To this order belong many cape-and-sword plays and detective dramas—­plays like The Adventure of Lady Ursula, The Red Robe, the Musketeer romances that were at one time so popular, and most plays of the Sherlock Holmes and Raffles type.  But pieces of a more ambitious order have been known to follow the same formula—­some of the works, for instance, of Mr. Charles McEvoy, to say nothing of Mr. Bernard Shaw.

We may take it, I think, that the architectural analogy holds good of every play which can properly be said to be “constructed.”  Construction means dramatic architecture, or in other words, a careful pre-arrangement of proportions and interdependencies.  But to carry beyond this point the analogy between the two arts would be fantastic and unhelpful.  The one exists in space, the other in time.  The one seeks to beget in the spectator a state of placid, though it may be of aspiring, contemplation; the other, a state of more or less acute tension.  The resemblances between music and architecture are, as is well known, much more extensive and illuminating.  It might not be wholly fanciful to call music a sort of middle term between the two other arts.

A great part of the secret of dramatic architecture lies in the one word “tension.”  To engender, maintain, suspend, heighten and resolve a state of tension—­that is the main object of the dramatist’s craft.

What do we mean by tension?  Clearly a stretching out, a stretching forward, of the mind.  That is the characteristic mental attitude of the theatrical audience.  If the mind is not stretching forward, the body will soon weary of its immobility and constraint.  Attention may be called the momentary correlative of tension.  When we are intent on what is to come, we are attentive to what is there and then happening.  The term tension is sometimes applied, not to the mental state of the audience, but to the relation of the characters on the stage.  “A scene of high tension” is primarily one in which the actors undergo a great emotional strain.  But this is, after all, only a means towards heightening of the mental tension of the audience.  In such a scene the mind stretches forward, no longer to something vague and distant, but to something instant and imminent.