Jim Henson started making television programs starring his distinctive googly-eyed creations—part puppet, part marionette—in the 1950s. And they were hits. Early versions of Kermit the Frog, Fozzie Bear and Cookie Monster made the rounds as guest stars on variety shows. Although fuzzy and feather-covered, Henson very much considered his Muppets as entertainment for adults—borrowing heavily from the song and dance variety shows of early television and Borscht Belt humor.

But when Henson was enlisted to put the characters on Sesame Street, they became known as children’s fare. It was a turn that Henson had some ambivalence about, and for years he struggled to reintroduce an adult sophistication to his creations. Finally, in 1976, the Muppets got a show of their own—one for all ages. But no American network had been willing to take a chance on a half-hour show of puppets, and so The Muppet Show was produced in England. The last season aired in 1981, and Jim Henson died suddenly in 1990. But the Muppets and many of their human performers are still with us. Still, while they’ve returned to movies and television with various degrees of success since Henson’s death, no one’s yet managed to crack the code and find the success the Muppets once had.

In 2015, to great fanfare, the Muppets returned to television, shocking and dismaying fans when Miss Piggy and Kermit broke up.

That 2015 iteration of the Muppets flopped, canceled after just one season.

It’s anyone’s guess what happens next with Kermit and Miss Piggy—and with the rest of the Muppets. But what happens to them … matters. The characters that Jim Henson created are not just among the most recognizable in popular culture.

They’re also among the most loved.

For the latest installment in its Peabody-Award winning American Icons series, Studio 360, the public-radio show and Slate podcast, looks at the origins, appeal and future of the Muppets.

Below is an edited transcript of that audio documentary, and a link to the audio follows that. Sally Herships is the producer and narrator.

The other voices are, in the order in which they appear:

Michael Frith, former executive vice president and creative director for Jim Henson Productions.

Brian Jay Jones, author Jim Henson: The Biography

Lisa Henson, CEO and president of The Jim Henson Company, and Jim Henson’s daughter

Mary Valentis, an English professor at the State University of New York at Albany.

Dave Goelz, the voice and puppeteer behind Gonzo

Matt Zoller Seitz, television critic for New York magazine

Michael Alcee, a therapist in New York City.

Sally Herships: Michael Frith worked as an art director and creative director for years for Jim Henson, who died suddenly and unexpectedly in 1990. Disney owns the Muppets now. And Henson didn’t create them by himself—he was more like a gentle shepherd, and a really talented one. It took a team of writers, artists and performers to create and put on The Muppet Show. Frith created many characters himself, including Fozzie Bear.

Michael Frith: Jim Henson would introduce me at various things and say something like, “Oh and this is Michael Frith, he’s sort of, he’s kind of, this is Michael Frith.”

Herships: Frith knows the Muppets. He loves them. But back in 1969 when he found out they were going to be on Sesame Street, he was shocked.

Frith: The creation of Sesame Street to me is one of the great absurdities ever. Because at that point the Muppets were strictly adult entertainment. What they were doing was blowing each other up and biting each other’s heads off, and things like that. Very non-kid stuff.

Herships: The Muppet Show characters didn’t pop out of Henson’s head fully formed. Some of the Muppets got their start as puppet stars of TV commercials back in the ’50s and ’60s. And they could be kind of dark.

Herships: If you didn’t try Wilkins coffee a floppy, early version of Kermit would threaten to shoot you or trample you with wild horses. (It was Henson himself who brought a piece of green felt and some ping pong balls as eyes to life, both voicing and operating Kermit.) Cookie Monster was originally created for General Foods. And Rowlf the dog became a pitchman for Purina. Henson worked his puppets. They made the rounds of variety shows like B-list actors trying to break into Hollywood. They did guest appearances on The Ed Sullivan Show, The Tonight Show with Steve Allen, and The Jimmy Dean Show.

For Henson, it all started when he was a kid in the 1940s and saw TV at a friend’s house. He saw variety shows and their frontmen like Milton Berle and Sid Caesar and he was hooked.

Later when he was in high school, and a local CBS affiliate announced auditions for kid puppeteers. He tried out. If it took puppets to get on TV, fine. A couple years later he had his own puppet show, Sam and Friends. It aired on a local NBC affiliate WRC-TV, in Washington, D.C. He was still in college. How does a guy this young get his own show?

Brian Jay Jones: The reason Jim was so successful so quickly was because both Jim and television didn’t know what the rules were yet.

Herships: Henson and TV grew up together. At that point in the 1950s they were both pretty young. Most puppeteers at the time would plunk down their puppet theaters and point the cameras at it. Like a Punch and Judy show. You’d see a little stage with a curtain and a puppeteer hovering nearby.

But Henson hid the puppeteers. Instead, he filled the TV’s frame with only the puppets. He even put monitors around the set so that the puppeteers could see exactly how it would look on television. And the strategy was successful—but not enough. What Henson wanted was a half-hour variety show of his own, and no one would give it to him.

Jones: Nobody really thought that puppets could stand on their own for half an hour on TV. They knew they were fine for two-minute bites on Sesame Street or The Ed Sullivan Show. But a half hour on their own? This was something really controversial and groundbreaking.

Herships: Jon Stone, a producer who was helping to launch Sesame Street had worked with Henson in the past and wanted him and his puppets on board. When the show debuted it was a hit. Ernie and Bert, Big Bird, and Kermit became puppet stars. But Sesame Street was a kid’s show. So Henson, who’d made all those dark, violent commercials, was now given a new label, children’s puppeteer—not one he wanted to be stuck with.

Jones: Jim is constantly in motion throughout the early ’70s pitching to the networks. And he finds Michael Eisner, who believes in that and gives him a shot to do a pilot, which he does. But the pilot doesn’t do very well, so he gets to do another pilot for ABC which also doesn’t do very well.

Herships: The show wasn’t quite there yet. Kermit was only part of one dance number. The host was kind of a boring Muppet named Nigel. And the name Henson had picked was The Muppet Show: Sex and Violence, which didn’t rub executives the right way. But one producer did say yes to the Muppets.

He was 30 years old, a former Laugh-In writer by the name of Lorne Michaels. And he was producing a new show called Saturday Night Live.

Henson had his chance. He would create all new characters that no one would mistake for his characters on Sesame Street—and he did it.

Lisa Henson: And to tell you the truth, at 16, I really didn’t realize they were bombing. Later on, it was more clear to me.

Herships: The SNL writers didn’t want to give away their best material to a bunch of puppets. Even John Belushi, who was nice to the performers, called them “the Mucking Fuppets.” The only one who seemed to like the Muppets performances was Henson’s agent, Bernie Brillstein.

Lisa Henson: And it just didn’t mesh and sometimes, you can hear a sort of deafening silence after those jokes and only Bernie Brillstein laughing in the silence, like he’s trying really hard to have his clients seems funny. But it just didn’t really work.

Herships: Nothing was happening until Lord Lew Grade, a British producer and media mogul, came into the picture. He might have been a peer of the realm, but he was a Jewish guy whose family had moved from Odessa to Shoreditch when he was a kid. He grew up to become a dancer. He looked like Fozzie bear, but bald and with a cigar. And he saw the potential of the Muppet show.

Jones: Lou Grade and Jim were were a generation apart, but they were cut from the same cloth. Grade had come out of the UK version of Vaudeville. He was famous for like jumping on an oval shaped table and doing the Charleston.

Herships: Grade gave The Muppet Show a green light. Finally, Henson had his half-hour variety show.

It was filmed in England and broadcast around the world. But the Muppets wasn’t just a show. It was a show within a show: Kermit as stage manager trying to get the whole crazy whirlwind zoo on stage. Miss Piggy the star, the diva. The Muppet Show was the archetype of a stage performance—and audiences loved it.

Mary Valentis: Well, I think they’re timeless characters. They go back to ancient Greece and the satyr plays exemplified in Shakespeare’s comedies. We’re thinking of the Taming of the Shrew. We get into Moliere’s French farce. And then move up into show-biz couples.

Herships: Kermit, the straight man, and Miss Piggy the diva. Valentis says it’s a classic pairing. A couple where one character is very flamboyant and plays off the other.

Valentis: And that happens in some of the Greek comedies.

Herships: The show even had a comedian who looks like he just walked off stage somewhere in the Borscht Belt. He’s got a pink and white polka dotted bow tie and a pot belly, except that he’s a bear. The show was self-conscious—and it had a sense of irony. It built in its own critics. Two grumpy old-puppet men in suits, sitting up in a balcony ready to pan everything.

Henson became a celebrity, and not like a Mister Rogers or a Captain Kangaroo. He was more like a rock star—but with puppets. The TV show was so successful it spawned feature films and made Henson even more well-known. Henson went through a period where he wore all white, believed in reincarnation, became a white meat vegetarian, and developed a fondness for expensive cars.

Jones: Yeah, Jim from early on loved sports cars. One of the gifts he was given, by Lorde Lew Grade—a Kermit Green lotus. This very low-slung, this almost James-Bond-looking sports car, which Jim loved.

Herships: There were vacations to France where he would bring co-workers and take them on hot air balloon trips. Jay Jones says he wasn’t just rich, he was also charismatic. Which helped the show land big stars. And helped its executive producer, David Lazer, keep them happy.

Jones: Women loved him. Men adored him. There was something about Jim that people sought his acceptance, his encouragement.

There’s a great story where Ethel Merman, in fact, when she was on The Muppet Show, she was wearing this very uncomfortable dress with a lot of feathers on it. And David Lazer went up to her at one point and said, “Do we need to give you a different outfit or something?” And she goes, “David, look, if Jim Henson wants me to wear a feather in my ass, I will wear a feather in my ass.”

Dave Goelz: You know, you talk to people who work with Jim, you might be excused for thinking it’s a cult.

Herships: Before Dave Goelz became the puppeteer and voice of Gonzo, the character had been created as a background character for a Christmas Special and then tossed into a box. He was pulled out for The Muppet Show, and the writers came up with the idea that he would be kind of a loser: shy, rebellious and out of place.

Goelz: That was exactly where I was. I was inexperienced, I had no background in show business whatsoever. And, I suddenly found myself one of the stars of one of the most popular, I guess it was the most popular show in the world at the time.

Herships: Goelz was only in his twenties. Both he and Gonzo were young.

Goelz: And when a guest walked in one door, I usually walked out the other door. Because I just thought, “I don’t belong here—I’m supposed to be on the couch at my parents’ house in Burbank.”

Herships: But one of Henson’s biggest talents was his ability to spot talent and ideas. Goelz says anyone from a stage hand to the janitor could make a suggestion and Henson would always think about it.

Goelz: We work in service of the best idea. So when we’re shooting, and anybody suggests something that sounds like it will work better, I’m going to do that.

Herships: Goelz says as he got older and wiser, and went to therapy, Gonzo evolved and matured along with him. Eventually, Gonzo played Charles Dickens in The Muppet Christmas Carol. And that depth of character is an essential part of the show’s magic.

Matt Zoller Seitz: They’re people. They’re people. You know, one of them’s a frog, one of them’s a pig. I have no idea what Gonzo is, I don’t think anybody does. But they’re basically people.

Herships: Seitz says the Muppets remind us of ourselves.

Take the relationship at the show’s heart, between Kermit and Miss Piggy.

Seitz: It’s a really dysfunctional relationship. For starters, Miss Piggy, let’s be honest, here—Miss Piggy is a handful. There’s just no denying that Miss Piggy is about as high-maintenance as it gets. And also Miss Piggy is a pathological narcissist. She really is. Like, if I was going to diagnose her, that’s probably where I would start.

Herships: So what’s coming in to mind right now is, wow, they need to go to counseling. Like, marriage counseling.

Seitz: If Kermit were my friend, I would actually set some limits. I’d have to say, look Kermit, I love you man, but either you have to break up with Miss Piggy, or you need to never talk to me about your problems again. Those are your two choices. I can’t have any of this grey-scale anymore ’cause it’s killing me. But if they were actual people that you knew, it would be a nightmare. An absolute nightmare. You wouldn’t know which one of them to block first on your phone.

Herships: Seitz says things are funny, as long as they don’t happen to us. And even funnier if they’re happening to a puppet. A little piece of felt and fabric on someone else’s hand.

Seitz: And there’s always that tension in comedy between catharsis and terror. And a rant, like a ranting raving lunatic like you get when Kermit finally loses it, and does that thing where he’s screaming and waving his arms? It’s really funny when Kermit does it. Cause he’s a little frog and he’s made out of green felt, but if he was a person you’d want to call the police.

Michael Alcee: What we see is Piggy dominates Kermit a lot.

And her ego gets the best of her. And Kermit goes along with it. He’s a really warm-hearted, soft-spoken, tender guy. And sometimes we all want to say, “Kermit, kind of, get a spine.” No pun intended.

Herships: Alcee says one reason we love watching is because we can all relate to Kermit and Piggy. They represent the different sides of our own personalities that we’re all trying to balance. Feminine versus masculine. Strength versus vulnerability. But with one key difference that was a big deal in the ’70s when the show was first produced.

Alcee: What’s so wonderful about the Muppets is that they flipped the usual script. So Miss Piggy represents the yang, which usually was the traditional masculine. And Kermit represents the yin, which is the traditional feminine. So I think also it was a healthy message for women to see they can have it all with that.

Herships: She can wear her gloves and her pearls.

Alcee: And be a badass.

Herships: Except in 2015, ABC tried to reboot the Muppets with a new television show. And in that version, Piggy was too much for Kermit, and they split. The show ran for one season. Then the network pulled the plug.

Unlike with the recent Muppet movies, fans did not respond well. After he dumps Miss Piggy, the new Kermit gets a new girlfriend—a younger pig. To fans, Kermit and Piggy feel real, like real friends or family. And in the new show the Muppets didn’t behave the way the Muppets they know would have.

After all, the original The Muppet Show is where a lot of fans first got to know the characters. It was like a golden age for the Muppets that established and defined them. And to take it on and get it wrong felt especially off-putting.

Along with Jim Henson, Michael Frith also worked with Ted Geisel, Dr. Seuss.

Frith: The best single lesson I got in storytelling was from Ted Geisel. He once said to me, “You can create any world you want. It can be as fantastic as you want it to be. But once you’ve created that world, you have to be true to its rules.”

Herships: Frith says Frank Oz, who played Miss Piggy, developed detailed back stories for each character.

Frith: He once describe Miss Piggy to me as having come from a litter of 17 pigs, but her mother only had 16 nipples. And if you don’t know that about her, I don’t know that you can really express who she is.

Herships: Frith says he hopes whoever is doing those characters now—in a movie, or new TV show—is going to the same kinds of lengths and depths and deep thinking.

Frith: I don’t want to put any of these people down, because they’re terrific. But it’s not, “How can I best imitate Jim or Jerry or Frank or whoever?” but, “How can this character truly live?” Because that’s what makes the Muppets truly magical.

Goelz: I think that it always comes back to Jim. He had a philosophy that drove him. And he didn’t talk about it much, but it was sort of about the idea that there’s enough in this world for everyone. We should be generous and share. We should celebrate diversity. And he created his company in that model for the world. And it’s a great model for the world. I mean the world could use more of that.

To hear a full audio version, listen to this episode of Studio 360 below, where host Kurt Andersen introduces the story at the top of the show, and subscribe to the show on Apple podcasts.