Most stand-up comics perform a set routine that they have committed to memory and then there are guys like Bill Cosby.

Cosby calls what he does onstage “swinging,” a term borrowed from jazz.

Reached by phone, Cosby said swinging as it applies to storytelling was first described by Mark Twain in an essay that must have prefigured the birth of jazz by several decades.

Twain compared global storytelling styles, Cosby said, concluding that American storytellers generally know how they are going to start and know how they are going to end but leave themselves the freedom to improvise along the way.

In a jazz performance, the melody is established, departed from and then returned to, Cosby said, and that’s how he tells stories.

“The way I work is that I have a set story – a story with a beginning, middle and end – but in the midst of all that I am also soloing,” he said. “It’s a feeling that one can have that is free.”

Cosby said he never knows when he steps out onstage what stories he is going to tell that night and in what order.

“I have argued with myself about what piece to do next because of the feeling of the audience,” Cosby said. “It’s not a negative feeling. It’s just a matter of taster’s choice.”

Cosby performs at 7:30 p.m. Sept. 11 at the Honeywell Center in Wabash (www.honeywellcenter.org).

Speaking of Twain, Cosby accepted the humor prize named for the American author in late 2009. Among the qualities the two humorists have in common is the timelessless of their material.

Cosby recalls a day on the set of “The Cosby Show” when the actor who played his son, Malcolm-Jamal Warner, expressed the desire to work some then present-day slang into the script.

“They all had freedom, as far as I was concerned, to ad lib, as long they stayed in character,” he said. “I think Malcolm was about 16 and really going through that phase of being connected to his buddies and friends and coming back to tell me if they thought the show was hip and the characters were hip.

“I had to mop up a lot of the stuff his friends were trying to deal,” Cosby said, laughing. “First of all, his friends were all unemployed.”

Cosby said he encouraged Warner to invent his own slang.

“I said, ‘Make up your own words, make that a part of who you are and what you are,’ ” he recalls. “ ‘When people see the show, they won’t have that connection to a word that is played out. They will know what you are saying because you are the one saying it.’

“He always remembers that as one of his favorite Cosby-to-Warner ‘don’t do that’ moments,” Cosby said.

Cosby said he remains close with Warner and Warner’s mother, both of whom are proud of Warner’s involvement in the show.

Cosby said his own mother, who died in 1991, was never comfortable with his choice of career.

“In her will, she left me $48,000 so that I had something to fall back on,” he said. “Her happiest moment, I am telling you, is the day I received my (doctor of education degree) from the University of Massachusetts Amherst. She knocked down a security guard to come sit on my lap and kiss me, all 4 feet 11 inches of her.”

Cosby is well-known for eschewing profanity and blue material in his act, although he said his initial motivation for working clean was the possibility that his mother could be out in the audience.

“I have never been about overturning any profanity carts into the street,” he said.

Profanity was a bold and daring artistic choice at one point, Cosby said, but that was long before it became numbingly ubiquitous.

“I think we may have come to a turning point in this,” he said, “where people may have heard enough of it, where kids are getting the idea that it’s actually edgier to develop something without profanity.”

As a grandfather, Cosby still connects with audiences the same way he did when he was a single man in his 20s: by describing things they have experienced in their own lives.

At one point in the interview, Cosby had to set down the phone to have a conversation with his 6-year-old grandson Avery and what ensued will probably end up in a routine someday.

Avery apparently wanted to order some DVDs off the Internet.

“You’re saying I can borrow these movies and watch them whenever I want to?” Cosby told his grandson in a wry and gentle tone of voice. “Are you getting me in trouble with grandmommy?…This is about 50 movies, man, that you ordered and you are telling me she said it was OK to order 50 of these? … It’s all right with me; whatever grandmommy says … Avery, don’t be angry with me … don’t be sad … this is going to happen … trust me, it’ll be all right.”

Cosby returned to the phone and whispered, “He tried to pull one over on me. He tried to suck me in by saying that I can watch the movies anytime I want to.

“That’s wonderful, but what he doesn’t know is that I have already seen this movie,” Cosby said, referring not to any of the DVDs but to the scenario that he and his grandson were acting out.

“I’ve had practice,” he said chuckling. “They come in here saying, ‘Look what I have for you. Watch this. This’ll be great,’ and before I know it, here comes grandmommy with fire-eating breath.”