Separated from the society that created them, most classic plays can be judged now only by their literary merit rather than by any one production. I find this cinematically attractive. I once generally bought into the critical notion that filming theater was a bad thing, but it strikes me now as a worthy challenge, something to truly question the bonds of art.
Theater is compressed in space and time. It is the immediacy of the actors and sets that give the stage a powerful attraction; this is denied in pictures. In film the immediacy is within the image, and a stationary camera and verbose actor are oppressive.
Expository dialogue is the spring for plot and action in the confined space of the stage, and a truly marvelous actor can shatter an audience with a well-delivered speech. Through speech, an actor carves emotions into his or her audience. I once read a fair acclaim of Shakespeare's soliloquies--that they define what it means to be human. Such is the power of expository dialogue in theater.
Cinema still uses expository dialogue heavily, but the primary force of pictures is in action. The emotions one needed to shout to a theater audience can be displayed in a simple close-up--action moves pictures.
Mistakes are made in filming theater:
-giving importance to expository dialogue (this is a mistake in most narrative cinema, not just filmed theater)
-giving importance to strong performances (also another mistake of plain narrative cinema, although a "strong" performance usually just means playing a radical character (uh, like mentally handicapped characters))
-confining space and time the same way theater does it--a flat, lazy camera, sparse and poor editing, etc.
-staying true to characters and plot-points and overarching themes; this is the literary sin of cinema.
Plays, however, are still uniquely desirable cinematic subjects. In some ways they are condensed and concentrated, and in others they are bloated and overly drawn; it is the power of cinema to expand the concentrated and concentrate the expanded. If you haven't seen this coming, Chimes at Midnight (1965) is my model for the challenges of filming theater. Four plays are simultaneously condensed and expanded, rearranged, rewritten, developed and critiqued, all within a cinematically engrossing whole. Only film can do this, and only theater can provide such opportunity.
Films like Major Barbara (1941) and His Girl Friday (1940) have helped me fight my snobbery against filmed theater, too. Each is faithful to its source, but both achieve a rhythm and power that the stage could never possibly imagine. I won't analyze any of these just now, but they represent just how awesome the challenge of filming theater can be. Such adaptations say more about the nature of film and the stage than a writer ever could.
To finish off these notes, a couple of plays I dream of filming:
The Frogs by Aristophanes
Heartbreak House by Bernard Shaw
-something by Moliere-
I am keeping watch for plays that might be given an excellent modern and thoroughly cinematic reworking if given to an adept filmmaker (not many around these days...). Any suggestions?