Few performing artists of the past 60 years are as iconic, or as mystifying, as William Shatner. The captain of the Starship Enterprise cut a heroic figure in the 1960s, when I watched the pilot episode of “Star Trek” as a preteen. Today, the hale and engaging actor, director, documentarian, author, singer, sportsman and rapper —who turned 81 in March—still seems possessed of boundless energy and bluster.

In many of his stage and screen appearances (and certainly in his music), Shatner often appears to teeter on the edge of self-parody. Face to face, he’s a warm hearted raconteur who inhabits his affable egoism without explanation or apology. I interviewed Shatner in June, shortly after the whirlwind national tour of his one-man show, Shatner’s World: We Just Live in It. On July 28 his new documentary about “Star Trek” fans, “Get A Life!”, premieres on Epix.

So how long do I have you for? How fast do I have to talk?

No; it is I who have to talk fast. It’s you who have to think fast. Half an hour?

Then we better get started!

I thought we already were.

You’re almost as well-known for your singing as for your acting. Did you grow up around music?

No, there was very little music in the house, little common music. My father would come home on Saturday afternoon, after six days of work. He’d grab a bite, lie down for a couple of hours, and play the Metropolitan Opera. That was the only music in the house: The Met from New York. So I never sang, or played an instrument. It was only when I got to McGill University that I began to write and direct and act in college musicals, and to admire Al Jolson and think: "God, if only I could do that."

What qualities in a song inspire you to create an interpretation?

I turn to my conservative Canadian, simplistic, uncomplicated background in music. I like to be able to hum the song and understand the lyrics. I love the musicality of words. Think about children's fairy tales. Fairy tales are supposed to be stories of inherent fears, dramatizations of human nightmares and cares and worries. The words "Once upon a time"—don't they suggest music? Sometimes words carry their own rhythm. I love to say the words and have the music enhance the words so that it aids and abets and supplants and supports those rhythms.

Some actors are like blank slates. I think of Meryl Streep in The Iron Lady. You can dress that woman up any way you like, and she will embody a totally different character. In your work, though—from the early Twilight Zone episode Nightmare at 20000 Feet through Shatner’s World— there's a substrate; like the base layer artists use to prepare a canvas.

What an interesting simile.

Can you define the single quality that unites all of your work?

That's me. Because my opinion is that even Meryl Streep, as wonderful as she is, can only bring herself to the role. For example, let’s look at you: a curly-haired guy who's athletic and intellectual, now being the observing reporter. I can play that. But I bring to it me, because all I’m doing now is imitating you. So even in The Iron Lady: Meryl puts on the wig, learns the smile and assumes—assumes—the persona. But she cannot bring anything else but her.

In your roles there's often a commanding tone; you’re cast as the man in charge. Is that who you really are?

It never used to be. But what has happened is, though I still realize I don't know what I’m doing, I've come to the conclusion that nobody else does, either—[nobody] knows what they're doing or knows what I’m doing. So in that mass confusion, there has to be a voice saying, "Well, here's where I am.”

I recently saw your documentary The Captains, in which you interview the four other actors who have commanded the Enterprise and its spin-offs. In the film, you make the surprising claim that for much of your life you suffered from a sense of inferiority. Do you think you've gotten over that?

Essentially not. It's just I don't put myself in those situations anymore. I once said to a girl—a society girl with whom I was having a fling— "Am I anywhere near the people you go out with? Have I got anything?" That's how badly I felt about myself. I look back on that question, and wonder what kind of a guy I must have been. 

You seem to have a good relationship with the other “Star Trek” actors in The Captains, as well.

 I love each one of those people. I didn't know them before making the film, except for Patrick Stewart—vaguely. Now they’re all friends of mine. I saw them recently, at the ComicCon in Philadelphia. All five captains were there—and all five are my buddies, based on a day or two in their presence.

Let’s talk about your recent one-man show, Shatner’s World. Performing live can be a huge challenge. I once read that many people would rather lose a toe than speak in public.

Well, I think it depends on which toe. If you look at the construction of the foot, that big toe really gives you a lift.

The success of Shatner's World was phenomenal. I wonder if there's a life lesson that you learned from the process of doing that show?

I'll tell you the life lesson I learned—but I don't know if I'll ever be able to use it again. I was first asked to do a one-man show in Australia. I said "Well, I’m not going to fly all the way there and do a one-man show; I've never done it." They said, "We'll send over a director, and you'll talk.

So we essentially put together a sequence of stories—an extended interview, if you will, with some songs and footage. And I had to make each of those stories dovetail. I had to have a beginning, a middle and an end. I realized, I’ve got to say something, I’ve got to have some meaning in what I’m doing. And so I spent months talking to myself, obsessed, trying to find the right words. Because if you find the right word, the rest of the sentence falls into place.

I finished the six cities in Australia and got good reviews. People clapped. And I thought, “Well, that's over; I’ve done that.” Then I was asked to tour Canada. And then I was invited to Los Angeles and New York.

The more I did it, the more rhythm it got. It started to take shape. But it still wasn't good enough. I had one week in LA, trying to put it together. Then I got to New York. We had a couple of rehearsals, and one preview. The night before the preview my wife and I went out to dinner. I wanted to be careful of what I ate, so I ordered a little hamburger. And I got a stomach flu that night.

So I’m looking at a Broadway opening, and I am frightened to death that I’m going to fail. I mean, I’m not going to die; I’ve got enough money in the bank to survive, I'll be able to pay the rent. But to be laughed at—stomach flu means you can’t go from here to there. All I know is, I've never been so frightened of anything.

What did you do?

I had to go on stage. It’s an hour and 40 minutes without an intermission. Somewhere in the middle, I had to stop the show and get to a bathroom. I said,"Ladies and gentlemen, there's been a technical difficulty. Don't move, we'll be back in 10 minutes." I dashed to my dressing room.

There's undoubtedly a life lesson in there somewhere.

The lesson is this: You never know what you can accomplish until you try. The problem is—what people don't talk about—is that a fair number of times, you fail. You try to climb K2, and you die. I faced that fear and was successful. There is a great deal to be gained by trying something that you’re horribly afraid of—because even if you do fail, you've learned something. Even if it’s that you don’t want to fail again!

It's easy to say “no.” Saying “yes” embodies risk. Yes to new ideas, yes to new opportunities, yes to doing a one-man show in whatever town I’m in. That's what my whole show is about: saying yes.

I know you’re a risk taker, but I wonder if you're also a creature of habit. Do you have a morning routine?

I love double rye bread toasted, peanut butter and tea. When my wife brings it to me in bed, it's an act of love that has to be repaid.

You’re known to be a man of many passions—and famously passionate about horses.

Yes; I run a horse show every year. The Priceline.com Hollywood Charity Horse Show, sponsored by Wells Fargo. We’ve raised a lot of money for kids, and now veterans. It benefits over 40 charities.

How did that come about?

People have an affinity towards things; you don't always know where it comes from. I got on a horse when I was about 12 years of age and started galloping around. My mother came up said, "Where did you learn to ride?" I said "This is the first time I've ever been on a horse." I just knew. I just felt the horse.

There followed a long period of time which I didn't have a horse, because horses are expensive. Now I have many, and I've been riding a long time. And on some horses, at some times, I’m in the zone: that Zen zone of unity. You can get there as an actor—and I've also gotten it as an archer. Zen in the Art of Archery [a classic Zen Buddhist text] explains how the bow unites heaven and earth, and the arrow unites you and the target. If you are really in the zone, you will lose that arrow at the most appropriate time. Riding a horse is like that. The horse is talking to you, and you're talking to the horse with your legs and your body. It's a beautiful art form, a legendary art form, as primitive as man: 10,000 years of horses.

What can you tell me about “Get a Life!”, your upcoming documentary on the mythology of “Star Trek”?

We are hard-wired to receive information in story form. If that information is about things that are unknown—death, the future, the universe—we devise stories to fill that gap. This is called mythology, and Star Trek has become mythological. The people who come to the conventions are participating in that mythology. I thought they were coming to see me; now I realize they’re coming to see each other!

In my 1999 book [also called Get a Life!] I did what I thought was due diligence—but I didn't go deep enough. I thought "Mythology? I’m part of a mythology?”

So you now see “Star Trek” as a cultural touchstone, not just as another television show?

It's not just another television show. But what does it tap into? What is the mythology? Well, the mythology is a group of people seeking out life. They're looking for the meaning of life, and of their own lives and relationships; for an explanation of all these mystical, wonderful questions that people ask and for which they have no answer. Their life journey. In Star Trek, we are the heroes; we are Odysseus.

Do you think mythology exists to explain the unexplainable or to set a code of conduct?

Probably both. Mythology needs heroes, and it needs villains. It needs heroes to fail; it needs heroes to struggle. Oh my god, the guy I worship, the guy I love, he fails— and tries again? Fears failing, and then succeeds? Kills the minotaur? Come on!

Is there someone like that for you? Outside of myth?

No; I think maybe I’m embodying it for myself. I don't know.

If you could choose one film clip to summarize your acting career, which one would it be?

I did a segment of a series called Rookie Blue, in which I played a grandfather whose granddaughter was stolen away at the age of 3, in his presence. He sees her now at 11—eight years later—and he comes apart. I followed the script vaguely, but I just let it happen. That could be the purest acting moment I've had in a long time.

The science fiction writer Arthur C. Clarke has a wonderful epitaph carved onto his tombstone: “He never grew up, but he never stopped growing.” Any inspirations for your own?

I wish I could be as erudite and as lyrical as that! But I've got mine right now—just in this moment. I hadn't thought of it before: “What was I afraid of?”

That’s really good!

I’ve got to write that down. What was I afraid of? Because I’ve been thinking about that: how the advent of death, to me, is frightening. I’m overwhelmed with fear and sadness. Look at all this! [Shatner gestures at the trees, the sky, the pool.] To leave this!

At 81, do you still have many long-term goals?

Absolutely! On Saturday morning I’m going to Dubai; I’m traveling 22 hours on an airplane, then getting on another airplane for Johannesburg. I’m going to do some work in South Africa, and then I’m going on safari.

I also want to live long enough to see my five beautiful grandchildren see their lives—I had so little time with my own three daughters, who now live close around me. And I've got to make more documentaries!

You seem to have a very far-reaching curiosity. Is there something you still wish to do that you’ve never done before?

I want to discover a truth for myself. Something that is really true: whether it's a piece of scientific knowledge or a philosophical truth. Like, “What was I afraid of?” I hope that's true. But I won't know until it's too late.

Jeff Greenwald, author of Future Perfect: How Star Trek Conquered Planet Earth, is a regular contributor to Smithsonian.