"Requiem for Methuselah" is a classic, but it's a different kind of classic. It tackles some of the essential questions of the series and reflects on later elements of the franchise as well, but in ways that may still be surprising.
Whether "What Are Little Girls Made Of?" or Harry Mudd is your fancy, artificial life was a running theme of the series well before Data in Next Generation or The Doctor in Voyager. The android in 'Methuselah" isn't necessarily the central figure (that would be long-lived Flint), but is at least another familiar type: a love interest for Kirk.
And perhaps this is the rival "City on the Edge of Forever" always needed. In "City," Kirk has to watch a love interest die. In "Methuselah," the love interest literally falls apart rather than choose between Kirk and the life she's previously known with Flint. Kirk falls hard for her, and at the end of the episode, Spock performs a kind of miracle for him, erasing his memory of the whole incident (a rare, organic reset button), an act of mercy that adds yet another layer of significance to the proceedings.
Yet the episode itself is an instance of the third season betraying its reputation for mediocrity, for failing to leave a good enough impression for the final run of the series. It's perhaps one of the best examples of the season being a reward for the fans, certainly for that closing scene with Spock, and for closure on a theme the show had attempted to explore multiple times already. And when you know the franchise would later finally tap this theme with main characters, "Methuselah" ends up becoming a preview (Voyager's excellent "Latent Image") of greater things still to come.
In a lot of ways, you can overlook the episode's significance all too easily because so much of it seems like so much you've seen before. But not like this. It's an experience of subtle pleasures and resonance. And none the less for it. It's a moment that catches everything the series tried to be all along, a profound examination of the human condition, and manages to do so with the fine touch seldom previously managed.
four quarter analysis
franchise * series * essential * character