I have been rewatching all of Star Trek: the Next Generation. Sometimes, I feel like I'm watching it just so I can understand who I am today.
I remember no television show or cultural event from my childhood nearly so clearly as Star Trek TNG: I remember tuning in to UPN to watch it weekly, I remember setting up furniture in my parent's room to mimic the shape of the Enterprise bridge, and I remember being absolutely freakin' terrified by the episode Conspiracy.
SHINING A LIGHT INSIDE
Star Trek: TNG is most fascinating to me because, much as I like to do with my work today, it uses its plots to shine a spotlight over particular ideas, played out as tangible dramas. Along the journey, Captain Picard and company get to play the philosopher-kings, and muse aloud over how the reality they're facing connects to ideas or philosophies. And all of this introspection is important because it's driven by characters seeking to understand themselves -- Data, struggling to be human; Worf, struggling to understand his Klingon heritage and his Starfleet present; Picard, struggling for moral clarity in a complex world.
So, it's been pretty interesting to see that theater is actually important to Star Trek. Characters turn to it to understand themselves. In fact, pretty explicitly, Picard and Data discuss theater as a road to self-understanding, which is pretty gratifying to see on a pretty popular television show.
THEATER AS CHOICE, NOT IMITATION
The first time that theater is discussed in a non-amateur context (there's some joke theater gags with Crusher directing a show, and some pretending to be actors in the distant past), Data is attempting to portray a role (Henry V), and his first idea is to access "the great performances." He has all of the great historical performances on file, and can recreate them note-for-note.
Picard rebuffs him, and tells him that the true creativity is in creating a role for ones-self. This same dialog comes up a lot in Data's musical life, where he also begins by imitating the "perfect" pitches.
Finally, in one musical performance, he creates a performance that seems unique. Picard asks him how he did this, and he says that he was not truly original -- he had basically sampled different approaches at different points. Here he was imitating one performance, there another. It was, in essence, a "remixed" performance.
But Picard points out to him that this is where creativity begins, because he makes choices between different performances, and thus has to display personal preferences.
IMITATING THE EMOTIONAL LIFE
The next time we see Data performing, playing Ebeneezer Scrooge, he has applied this lesson to acting. Again, this earns him positive reinforcement from Picard, who asks him how he has approached creating a "unique" performance this time.
Although Data frames his response in terms of "The Method," and the Acting Studio "of the early part of the 20th Century," Data's approach is actually strictly speaking a Grotowski approach. He talks about imitating the physical externality of fear and anxiety, and exploring those physical forms to try and understand the mindset behind the person who would display those forms. This is learning the emotion from the outside in.
It's subtly different from what Grotowski was getting at. Grotowski believed that the muscle memory would spark the emotional memory, but of course for Data that crucial link is missing (he has no emotions, and his "muscles" don't exhibit memory). This is why he invokes some of the language of "The Method," specifically in terms of imagining what it would be like in those circumstances (which is more Stella Adler than Stanislavsky).
But it's basically the same. Since he can't simply recall memory, he takes a physical form, and tries to understand the reality based on that physical form. And again, it's the beginning of entering into the character.
THEATER AND MADNESS
And of course, there's the excellent episode Frame of Mind, where Riker is rehearsing for a play about insanity prompted by torture, but realizes that he is actually trapped inside his own mind, prompted by torture. The repetition of the theatrical events is part of the madness. I wouldn't necessarily say it sheds a lot on theater or how it should be done, but it's a damn compelling episode.
Speaking of which, the Original Star Trek had an equally excellent episode, Conscience of the King, where Kirk discovers that a mass murderer has been hiding in a new life as a Shakespearean actor, but can't wash the blood off his hands from his deeds. On the one hand, theater allows him to transfer his guilt and pride into epic characters; on the other hand, his daughter can't separate the theater from life:
Looking back, I can't think of any fictional shows that treated theater with as much respect as the Star Trek series.