Given some basic wisdom, directing for the stage is rather simple. The wisdom is that: “The audience don’t care.” They don’t care where the characters “went to school”, or what memory the actor is dredging up to influence his performance; they just want to see a show.
The show they see on an opening night will consist of two things in existence prior to rehearsal: the actors, and the script. The actors don’t need to discuss the script, they understood it when they read it. They don’t need to zhuzh up their performance through elaborate analysis, they just need to show up and speak up — the subsequent performance will be appreciated on their ability to do so, and on the worth of the script. No performance can enhance a bad script, and a good one needs no help.
Prior to the Twenties, the director was known as the stage manager. It was his job to block the actors such that the audience could see them and hear them, and they didn’t trip over the furniture. “Louder, faster, pause here, don’t fidget while the other fellow is speaking”: these were the panoply of the director’s tools.
But the cobb salad of psychoanalysis and the method replaced the stage manager with the director. His job was to analyse the script psychoanalytically, and lead the actors in a month-long encounter group called the rehearsal process. None of it made any difference to the audience, save that the self-consciousness the charade engendered in the actor, transformed him from performer, to lay analyst. After all, anyone reading a play text understands it sufficiently to appreciate the interactions. And the better a play is, the less it needs a set — Shakespeare plays just peachily on the radio.
So past simply staging, then, in his responsibility to the audience, how might the director (ex-stage manager) be of use to the actor? In one thing: a subtle alteration of the actor’s intention. The fellow playing Iago understands that he is going to avenge himself on his boss by falsely accusing Desdemona. The actor might play a scene revealing the false clues to Othello as “conveying a favour”; the director might suggest, rather, that he play it to “refute a false claim”. The words are the same, but the intention (known as the objective) is somewhat different, and the change will influence the performance subtly.
Note that in neither case is the actor asked to “feel” anything, or to “believe” anything, he is simply asked to reimagine the objective.