There's an elegance and simplicity to "The Inner Light" that is hard to quantify but important to consider, because it's crucial to the effect of this classic TNG episode, which is a shining example of not only Star Trek but of science fiction. The story told here is actually quite straightforward, but the implications are hauntingly significant and affecting, and provide nothing less than a contemplation upon our own mortality — as individuals as well as, someday, inevitably, our entire civilization.
The best science-fiction stories are usually the simple ones that take an idea and consider how it affects us as people. TNG has a tendency to often be about problem-solving, and how to invent fictional tech solutions to solve fictional tech problems; in many cases the problem and solution are arbitrary concoctions of a writer trying to get from A to B. TNG became very good at this particular formula of sci-fi — to so much a degree that if you asked me to sum up what the essence of TNG was in a single phrase, my answer would be "problem solving." But a story like "I, Borg" or "The Inner Light" is more about the bigger questions behind far less arbitrary sci-fi machinations. It's about how the trappings of sci-fi can be used to tell stories about the essence of the human condition. Forget about cliffhangers: This episode could've been a wonderful season finale to this or any season of TNG.
The Enterprise encounters an automated probe that attaches a telepathic beam directly to Picard, who collapses on the bridge and goes into a state of unconsciousness. Picard awakens to find he is an everyman in a small village on a world called Kataan, where everyone knows him as Kamin. He believes he is still Picard, but his wife Eline (Margot Rose) tells him that he has just awoken from a long fever and must be delusional. He has a good friend named Batai (Richard Riehle). Gradually, Kamin resumes the life on Kataan that he doesn't remember. Back aboard the Enterprise, the crew attempts to disconnect Picard from the probe, but they fail.
Every time the narrative returns to Kataan, years have gone by — eventually decades. Kamin builds a life, has children and grandchildren, has long conversations with his wife, grows old and gray with her, and eventually watches her die in his arms. All the while, he can't shake his interest in the heavens, where he remembers, perhaps as a delusion, of having been a starship captain so long, long ago. Also quietly in the background, an ominous subplot slowly but surely develops, with talk about droughts that keep getting progressively worse, and whispers that something terrible may be on the horizon.
The secret of "The Inner Light" is that the world of Kataan has been gone for 1,000 years, destroyed by a supernova that its residents had no hope of escaping. The probe was their interactive time capsule meant to deliver the history of their world to one person, via the very specific experience of becoming one of them and living a life among them. Interestingly, we are given all the information necessary to solve this puzzle well before the story's true moment of epiphany where Kamin/Picard himself realizes the nature of his existence on Kataan after 30 years with them.
Fascinatingly, this has the effect of making Kamin's/Picard's epiphany more poignant rather than less. We realize what's happening to Kamin's world before it occurs, and it's that foreknowledge that makes both the value and the tragedy of Kamin's life all the more profound and heartbreaking. Here's a man — and a society — that knows the world is ending and that everything about their civilization is coming to its imminent and inevitable end, and it's only through the launching of a probe into space — with the hopes that it might, someday, just maybe, find someone else and teach them who they once were — that the world of Kataan is able to survive.
The wonderfully hopeful and heartbreaking, recursively paradoxical moment of epiphany comes at the end of the probe's program, where Kamin realizes that he, who once was Picard 30 years ago in a long-forgotten life, is the very person who will receive this message — because Kamin was Picard, and now Picard is Kamin. (Intriguingly irrelevant question: Was Kamin based on a real person on Kataan, or was his whole existence an invention for the purpose of the interactive program?)
"The Inner Light" isn't simply about that moment of Kamin's final realization, but about how all the moments up to that point have created a fully formed life full of joy, family, wisdom, sorrow, and ultimately the acceptance of one's mortality. It is, in short, a story of the human experience. It's a concept that's beautiful in the depth of its meaning, and yet astounding in the simplicity of its procedure. Of course, none of this would be possible without Patrick Stewart's fine performance. (I found some of the old-age makeup to be less than convincing at times, but never Stewart's ability to inhabit it.)
Key to the effect of all this is that after the program ends and Picard wakes up back on the bridge, the effect of the mere 25 minutes of being connected to the probe is as if Picard had literally lived those 30 years of memories (*), only just now returning to his long-forgotten, distant shadow of a former life. In the episode's coda, Riker visits Picard — still getting acclimated to life aboard the ship — and says the probe's program terminated after disconnecting from Picard. It was a message meant for an audience of one, who now is the sole carrier of the dead civilization's history. While functionally and logically I'd say that putting all of Kataan's eggs in one basket is an awfully risky way of preserving that history, I will also say that it's somehow the perfect emotional note for this story. Also, inside the probe is the flute that was Kamin's lifelong pastime, now a gift for Picard — who holds it dearly (Stewart is perfect in this wordless final scene) and then we see that he knows how to play it. Whoa.
"The Inner Light" is a brilliant and contemplative sci-fi elegy, and one of Trek's finest hours.
* The episodic nature of TNG proves here to be both a blessing and a curse. I would be remiss to point out that if, as is suggested, Picard really returns at the end of this hour exactly as if it's been half a lifetime since he last was himself, then he should be a fundamentally different person forever. Basically, everything before this episode took place more than 30 years ago from his perspective, and there should be psychological consequences to his life as Kamin.
But because TNG is episodic, none of this will matter by the next episode. That feels like a cheat, and I hesitate to suggest that maybe it should've been mentioned here that the effect of these artificial memories might fade more quickly than real ones, or become more dreamlike after the initial experience wears off, because that would rob "The Inner Light" of a lot of its power. I guess at a certain level, these are all fictional characters in a format of TV where most everything is erased by the next episode, we have to accept that, and that's all there is to it.