Characters in plays are brought to life by actors. The most bizarre and mannered behavior and dialogue can become realistic in the right hands (and body, and voice). See MAMET David for examples.
Borges and Bioy Casares were almost certainly talking about something else, about the verisimilitude of the characters in Shaw’s text, with the reader’s imagination filling in, however inadequately, for the actors. Shaw is unusually aware of the issue. He had great trouble getting his plays produced and instead made his breakthrough by publishing them in cleverly titled books – Three Plays for Puritans, Plays Unpleasant, and Plays Pleasant, the latter containing Candida.
So Candida is written to be read like a screwy novel. It begins with the point of view hovering over London, and then moves into a specific neighborhood in the “north-east quarter,” no, not that slum, but the middle-class neighborhood next to it, “wide-streeted, myriad-populated; well served with ugly iron urinals, Radical clubs, and tram lines carrying a perpetual stream of yellow cars.” One detail in that list was a surprising reminder that the Victorian times, they were a’changin’, and followed by that stream of – ya know, I’m just going to move on.
Now we’re on the street, then a park (“it is a pleasant place”), and on the other side is a parsonage. Through the door, up the stairs, and into the room that serves as Reverend Morell’s office. We are finally in the theater, looking at the set – books (William Morris, Henry George, Karl Marx and other “literary landmarks in Socialism”), chairs, a fireplace, a typewriter. The whole point of this is to thicken the reality of the world of the play, and the same treatment is given to the characters and their gestures. Let the theater director worry about what the stage would look like.
The nice, plump details of characterization are mostly those a novelist could use. Little gestures, bits of speech that are a step left or right from where I expected them to be. Act II begins with the office occupied only by the poet:
Marchbanks, alone and idle, is trying to find out how the typewriter works. Hearing someone at the door, he steals guiltily away to the window and pretends to be absorbed in the view.
Of course that is what he would do when left alone, of course. Let’s look at another, the father-in-law this time, who is disappointed to learn that it will be a couple of hours until dinner:
BURGESS: (with plaintive resignation) Gimme a nice book to read over the fire, will you, James: thur’s a good chap.
MORELL: What sort of book? A good one?
BURGESS: (with almost a yell of remonstrance) Nah-oo! Summat pleasant, just to pass the time.
“Almost a yell,” that is very nice – I don’t trust that bookshelf either – but now I can also see how the actor playing Morell works backwards, perhaps making his questions a deliberate tease. Polite but arch, put the emphasis on “sort” and “good.” Morell is played by Kelsey Grammer, Burgess by John Mahoney. Give ol’ pop a good scare.
The firm lifelikeness of the characters in Candida are easy to see. This experiment was a success.