As if in answer to the previous episode, again Trek expounds upon the topic of ambition. Whereas then we were dealing with an opposition of unhealthy ambition, here we encounter an equally threatening lack of ambition: total contentment. It is this mature theme of moving past the duality of extremes that permeates this episode, and manages to also comment upon the main character's relationship.
The Enterprise crew comes in contact with what amounts to a commune of space druggies. The small clan of travelers are hyped-up on a spore-induced drug that grants them complete harmony, free of want and need. Thankfully, the implications of the anti-drug message are never exploited in any way beyond legitimate dramatic and thematic ends. I found myself dreading the setup, and then delighted that the obvious path was not taken.
When the crew gets subjected to the effects of the spores one-by-one, Kirk is able to observe enough to derive it's failing: Man was not meant for paradise. There is a brief allusion to Eden, a brush with biblical subtext. While the relative snub may seem like further evidence of the often postulated atheistic viewpoint of Star Trek, I rather see this as a balanced acknowledgment of the universal philosophy depicted by the tale of Adam and Eve. As this is a subject hardly exclusive to any one religion, it is not dwelled upon. Rather, it is integrated in plot and character based fashion.
Plot wise, Kirk is able to defeat the spore's extremism by canceling it out with equally extreme rage. The drama is plotted beautifully, as Kirk is forced to enrage Spock. Even beyond this, our favorite Vulcan is treated to an extra dose of attention this episode. Running into an old acquaintance with feelings for him, Spock's internal conflict is brought to the fore. While some may deride Spock's intoxicated enjoyment as silly, I find it tragically telling of his character and paramount in establishing him even further as an evolving person.
"If there are self-made purgatories, then we all have to live in them."
That being said, his position in the "holy trinity" is not compromised. In fact, this episode acts as a pivotal installment in defining how Kirk, Spock, and McCoy relate. Ambition can only be realized through moderated action. Informed by the extremes that live within us (Spock/McCoy), yes, but acting only through careful reconciliation of the two. (Kirk) What better way to illustrate this than by dramatically showing the drearily unambitious consequences of excess?
McCoy: "That's the second time man's been thrown out of paradise."
Kirk: "No, this time we walked out on our own."