This is that one episode of the original Trek series which contained a certain inspired, sublime quality, which transcended the limitations of even the best episodes (translation: 10+ stars). We know there is greatness here, but what exactly is this impression that staggers us? Famed writer Harlan Ellison wrote the original teleplay, which was re-written by other hands (causing some controversy that continues to this day) to presumably make it fit better within the confines of Roddenberry's and television's view of the Trek universe. Very briefly, Ellison looked at human beings as more flawed (which, of course, they are) and probably regarded Roddenberry's vision of near-perfect future humanity as a bit too bland. This is television we're speaking about here, when all is said and done, and blandness is de rigueur. But, even the re-writes could not reduce this magnificent piece to anything less than the masterpiece of its day.
The City that the title refers to, on the surface, appears to be the eerie setting we see in the first act, with ruins, as Kirk notes, stretching to the horizon. It is here that we first see the Guardian of Forever, a strange rock-like arch which actually functions as a time portal. We've all seen time travel stories before, with similar devices ("The Time Travelers" from '64, for example). But, it's what happens after we enter the portal that then defines the story and weaves a tale of bitter, even mind-numbing tragedy. There's a chill odor assaulting us even before all this happens, a foreboding, as the Guardian intones 'All that you knew...is gone' after a deranged McCoy leaps into Earth's past. Without having to show the audience anything - anything physical or expository - the story lets us know that the Federation has been wiped away. All that in the span of a few seconds - all gone... just gone. The cosmic hook is that a particular individual, just another citizen in the dim past, can have a profound effect on the course of events within the known galaxy, while others, such as a skid-row bum, would have no effect at all.
The City may also be the city of New York, in the 1930's, for this is where a piece of Kirk (or his heart) will always be - forever, as it were. During the week that Kirk and Spock are forced to live a brief out-of-time life there, the story now stirs in the most potent human elements with the most dire cosmic dilemma - it's a fantastic, unforgettable mix. Unfortunately for Kirk, this was the one scenario he was not trained for. You might note, watching any of the other episodes, no matter how outlandish the threat or problem, it's always something Kirk is able to take control of eventually, to grasp and handle in his own persuasive manner. Not here - gradually, he becomes helpless, caught in the undertow of that perhaps strongest of human emotions after he meets a social worker. As with everything in this episode, actors Shatner and Collins seem to transcend their normal limitations. It's amazing that this episode, at least while taking place in this timeless New York City, is only the length of about half-an-hour; it seems like we're with Kirk & Edith for a good week there, much as it was meant to be.
As I got older, I found it almost too painful to watch the final act of this episode. It's like a piece of music - so well done, you're compelled to listen, but the notes are heart rending and leave that dull ache, as if you're missing something in life. As a comparison, I would bring to your attention another episode, "Requiem For Methuselah" from the 3rd season; it's actually not that bad of an episode, not without interest. But, in that one, Kirk falls in love in the span of an hour and then Spock erases his pain with his Vulcan abilities. Nothing so trite here. By the look on Kirk's face and his words in the final scene, as he dismisses the incredible Guardian, we know he will have to live with this pain forever. 'All IS as it WAS before' the Guardian intones some more. I'm afraid not. Not ever.
