Ira Glass’s transition to unobtrusive television presence from invisible radio host is as smooth as the substance denoted by his surname. At 48, he has a thick crop of hair, a symmetrical face, black-framed glasses, a dark suit, and a boyish, old-school reporter look. When we see him, he is usually sitting at a desk, much like any talk show host, except that this particular desk changes location from episode to episode. Sometimes it’s on the cusp of a freeway, at others in front of a mountain range or in an underground parking lot or plopped down in the middle of a suburban garden (with a power plant belching smoke in the distance). It’s a nifty visual metaphor — Office America — in a show full of them.

Rather like the writer Lawrence Weschler (“Mr. Wilson’s Cabinet of Wonders,” “Vermeer in Bosnia”), Mr. Glass is hooked on the wonder and strangeness of life and all the surprising patterns and paradoxes it reveals under the storyteller’s microscope. Since 1995, he has used his public radio show, “This American Life,” to tell the kind of true-life stories that once would have been considered too quirky and unglamorous to qualify for television. But television has changed. With more channels and niche groups than ever to be filled and satisfied, eccentricity is increasingly tolerated, even prized.

The radio version of “This American Life” is carried on over 500 stations and attracts an average audience of 1.7 million listeners every week. That might not impress an executive at CBS, but on cable it’s a different story, which is why “This American Life” will make its debut on Showtime on Thursday.

When possible, Mr. Glass likes to bundle different stories in thematic clusters, and the basic model for each half-hour episode (though freely deviated from) is to begin with a vignette, a kind of appetizer that tangentially presents the episode’s theme. We then meet Mr. Glass, who, while seated at his desk in whatever remote outpost he has chosen for the week, provides a gloss on what we have just seen and enunciates the idea or thought that the next two segments — or “Acts” — will pursue and illuminate.

The opening episode, called “Reality Check,” is about people who introduce artifice into their own or other people’s lives in questionable ways. It begins with a dramatic re-enactment of a woman’s memory of being on a school bus as a young girl, stuck in a traffic jam. We hear and see the woman as she is now and watch the actress who plays her youthful self. The girl, who is seated alone, though the bus is crowded, desperately needs to empty her bladder, and the idea comes to her to do so, silently, into the empty space in front of her seat. No one, she thinks, will notice. But as the bus lurches forward in the starts and stops of traffic, the puddle of urine at her feet slides slowly toward the back.

Pandemonium breaks out and all the kids, save the girl, jump up and start dancing madly about the bus. Everyone knows who did it, and it takes years for her to live down her shame. She is dubbed “Peezilla” and her peers are forever leaving yellow crayons on her desk.

“That’s how it goes sometimes,” Mr. Glass says in his trademark voice over — a kind of clipped drawl. “You have this plan, this sudden inspiration, this dream, and then reality kicks in.”

The segment, which is brief, may be the weakest in the entire six-episode series and bears only a glancing relationship to the episode’s central theme. Nonetheless, it introduces Mr. Glass’s new audience to his longstanding fascination with childhood, and establishes that the television version of “This American Life” is not just going to be visual in a by-the-numbers way. It is going to be ambitiously visual — colorful, kinetic, and far more stylized than the average documentary. The series is directed by Chris Wilcha (“The Target Shoots First”) and co-produced by Christine Vachon of Killer Films, the company responsible for such indie favorites as “Boys Don’t Cry,” “I Shot Andy Warhol,” and “Hedwig and the Angry Inch,” to name just a few.

The show’s transfer to television has been in the works for five years, and no one has made any foolish blunders. The photography is so rich and varied (according to the kind of story being told), and so much narrative information is imparted visually, you would never think the origin of the series lay in radio.

The introductory vignette over, we move on to the two main segments. The first is about a rancher named Ralph Fisher who decides to have Chance, his pet bull, cloned. Unfortunately, Second Chance doesn’t turn out to be as friendly as his predecessor, and we watch as Ralph slowly comes to terms with that fact while stubbornly insisting that the difference between the two animals is minimal.

The second segment is about Improv Everywhere, a New Yorkbased group of (theoretically) benign pranksters whose leader, Charlie Todd, decides to give an obscure rock band called the Ghosts of Pasha the night of its life by getting 35 of his “agents” to memorize the group’s songs and then show up at a small concert in the guise of worshipful fans. The band members, who had no fans to speak of at the time, were startled to see so many devoted followers at a tiny gig and were under the impression they had made some sort of breakthrough. A few days later they learned the truth about their dream concert, and the “fans” who attended it. The segment tries to evaluate the nature of the prank and its longterm effects, both good and bad, on the group’s psyche.

Like the first segment, it is about the consequences of (in Mr. Glass’s words) “messing with reality,” a tendency which he sees as inevitable, at times regrettable, but inherently human. Thursday’s episode of “This American Life” isn’t necessarily the best. In fact, the series improves as it goes along. The final installment, about a memoryerasing drug, genetically modified pigs, and an incredibly raucous hamburger stand, is a mini-masterpiece which gives the “messing with reality” theme a full-scale workout. One of the nice things about “This American Life” is that, because each show is entirely self-contained, you can drop in on it at any time and find something of interest. It may well be around for as long as the radio show.

bbernhard@nysun.com