Leonard Nimoy, who passed away this past Friday, was less an actor than an icon, an ever-present figure and a seemingly universal pop-culture touchstone. What struck me, upon hearing the news of his death, was that I’d somehow assumed he couldn’t die. It seemed as if Leonard Nimoy had always been there, in one form or another—as Spock, as himself on the best episodes of The Simpsons, as the man singing that ridiculously earworm-y theme song to the animated Hobbit movie—and I’d believed he always would be.

Not bad, for a guy whose biggest claim to fame was a TV show that was cancelled after three seasons. Despite his understandable discomfort with being identified solely with Star Trek (his first memoir was entitled I Am Not Spock, after all), it’s Spock, and Star Trek, that will be Leonard Nimoy’s most lasting legacy.

The role also explains much of the emotional hold he had on fans: he was the purest and clearest symbol of Star Trek’s utopian vision. Spock was an icon of perfectible human nature existing in a perfected world.

The Star Trek universe’s political vision is fun in part because it’s so massively impractical. The reasons I adored it as a child are the same reasons I find it so charming today. To start with, Star Trek is explicitly post-capitalist. No one worries about money; the characters seem to show up to work simply because they like being there. And the one alien species that does operate on a capitalist structure, the Ferengi, are villains. Yet the Federation is entirely devoid of the problems anti-capitalists face now: no one gets stuck with a crap job on the spaceship, because all of the “bad” jobs (factory labor, secretarial work, cleaning the Holodeck) are automated. No one has to worry that sharing resources will deprive them of things they want; in the Federation, everyone is comfortably middle-class, if not rich.

Needless to say, this is impossible. As ecofeminists like Vandana Shiva and Maria Mies have repeatedly affirmed, affluent, technologically enabled Western lifestyles simply can’t be universalized. (See, for instance, this excerpt from their book Ecofeminism (PDF). In the real world, at least, the Earth is a closed system. There’s only so much stuff we can use. Western ideas of “comfort” or affluence depend on Westerners using up vastly disproportionate amounts of that stuff, which depends on global capitalism, which depends on strategically impoverishing other countries and using them as a source of exploited labor. We can create a world where no one is poor, but never a world where everyone is rich; the Earth simply can’t produce enough to support that level of consumption.

But you know what solves the problem of the Earth as closed system? Spaceships, that’s what. In Star Trek, there is infinite Stuff, and whatever you don’t have, you just find on a new planet, or get from the replicator. Poverty and exploitation are things of the past, because their fundamental cause—competition for limited resources—simply doesn’t exist.

Star Trek’s perfect social reality is nothing next to its vision of perfect people. It’s not so much that Star Trek is dorky—although every character on those shows is deeply dorky—as that it lacks the necessary conditions for coolness to arise. There’s no counterculture; the culture is already perfect, so who’d want to counter it? There’s no youthful rebellion—even Wesley Crusher, the much-abhorred teenage pipsqueak of Star Trek: The Next Generation, hangs out mostly with his mom—because there’s nothing to rebel against.

If the Federation can seem humorless, it’s only because the keenest humor, as Freud reminds us, arises from hostility; in Star Trek, interpersonal hostility has been replaced with an all-encompassing sweetness, a sense that, although the characters on the Enterprise may chafe each other occasionally, they’re ultimately friends, making common cause in the best of all possible worlds.

Which brings us to Spock, and to Nimoy. Though Spock is half Vulcan—and, as such, treated to some of the show’s few explicit acknowledgements that racism might not just disappear, via McCoy’s frequent references to him as a “green-blooded goblin”—he was also Star Trek’s clearest statement of what a perfected human might be. His character is cleansed of hatred, fear, greed, and self-destructive impulses, just as the show’s universe is cleansed of oppression. He is a strict rationalist; the show, likewise, puts its faith in science to resolve all practical and emotional problems. If someone is getting on Spock’s nerves, he merely remarks that their actions are “highly illogical.” If something threatens his life, he’s more likely to call it “fascinating” than panic or run away.

Try to visualize Spock yelling at someone in rush-hour traffic. Visualize Spock in the midst of an acrimonious divorce, or picking a pointless fight with a friend after a rough day at work. You can’t. Those are the parts of human nature that are ugly and hard to manage, the parts that we don’t like, and that others don’t like about us. Spock has none of them.

Ridding ourselves of hostility and irrationality is just as impossible as everything else in Star Trek. Nimoy’s great gift as an actor was to make it seem plausible: With his seriousness, with his stillness, with the reserves of humor we could always sense glinting just under the surface (that eyebrow!), he made Spock a real person, and so gave our ideal selves form. That gift made him the most beloved character in one of our most beloved stories. And Star Trek granted him his own measure of immortality. Leonard Nimoy couldn’t stay with us forever. But Spock can.