You have played all the parts, rehearsed every line. You know the script like a memorised prayer. Yet now you are outside the play, sitting in the front row of the audience. Time has passed, and you have been in other productions since, with different dialogue, props, and sets. You realise that there are other, perhaps even better, ways to interact on stage--if only you could convince the actors to change a few lines, alter their blocking and stance.
But that is impossible. Instead you must watch the play from your darkened seat, unable to change one line of the script, to spare one moment of tragedy or prolong one second of joy.
Yet you are not at home as an actor in your new theatre company either. They are just as determined to deploy the parts they have been given, to play out their hard-earned roles, their charming traits and tragic flaws, to the inevitable conclusion. Sometimes you make a bit-part appearance on one stage or the other, but even then you are mostly just watching. The actors are people you care about, love, but they refuse for even a second to break character. After all, they are good at what they do.
Try to alter a scene even slightly, and determination flashes into their eyes, as if to say: "We are the people of this theatre group, and this is the way we must do it." So you play your small parts. You let them play theirs. You learn to enjoy the all-too-brief moment at the end of a scene, when the lights fade to black, encompassing all of you--actors and audience--in the stillness, the same sweet dark.