The metaphysics of reincarnation posits a new mantra with every rebirth, but Allen Rosenshine has always adhered to his old incantation: “The work, the work, and the work.”

He used that mantra to transform the advertising agency BBDO Worldwide – of which he’s chairman – into a creative powerhouse, with annual billings of more than $7 billion. Along with another iconic figure, Keith Reinhard, chairman of DDB Worldwide, he was the driving force behind the creation in 1986 of the Omnicom Group, the world’s biggest holding company of advertising and marketing companies. He served as Omnicom’s first chairman and CEO.

He used that mantra, too, in extending his energies on behalf of the Partnership for a Drug-Free America.

Mr. Rosenshine’s experience in the advertising world certainly lends itself to a narrative between hard covers. Thus, he’s written a book, “Funny Business: Moguls, Mobsters, Megastars, and the Mad, Mad World of the Ad Game” (Beaufort Books). Amazon.com has announced that it will be published May 30. He prefers not to discuss the book, because it is still being edited.

He has also started writing movie reviews.

“The reviews are just for my friends,” Mr. Rosenshine said, carefully skirting around the fact that his cohorts could quite possibly fill several megaplexes. He sends the reviews to them by e-mail, as he does to his wife, Missy, and children Andrew, John, Elizabeth, and Laura.

Why not create a Web site for these reviews, or write them for publication?

“Hmmmm,” Mr. Rosenshine said, with a twinkle in his deep-set eyes and a facial expression that suggested the question had been offered before.

“But I’ve never been one for self-promotion – even in a business of huge egos,” he said.

“Perhaps that’s because I’ve always thought first about my clients’ needs,” Mr. Rosenshine said. “It’s all about your clients, all about the relationships that you establish – and how you maintain those relationships. No matter how good your presentation is, it comes down to whether your clients like you, what they think of you as a person.”

Mr. Rosenshine paused to pick at his bay scallops.

“And the reason some people in advertising don’t understand this is that they’re too self-absorbed,” he said. “There’s too much arrogance in this business. The ad business breeds that arrogance. But at the end of the day, you’re only selling yourself and your ideas. But before you get an account, you’ve got to reach the people who make those decisions.”

Such decisions translate into stratospheric figures. Last year, corporations in North America poured $173.3 billion into advertising; the worldwide total was $403.6 billion. In 2006, they are expected to spend $182 billion out of a global total of $427.3 billion, according to a research company based in London, Zenith OptiMedia.

To access such numbers, Mr. Rosenshine said, ad agency presenters need to put on a good show. But there’s always a caveat.

“It’s not that important who’s making the presentation – the creative director of the agency or the account executive,” he said. “It’s far more important that your clients trust you, if they like you. And from an ad executive’s perspective, it’s absolutely essential that you listen to your clients. When I was supervising campaigns, I always responded to what my clients said, what they wanted.

“Some people in advertising are so full of themselves that they cannot listen to others,” he said. “Advertising is a reactive art. Advertising doesn’t create trends; it follows them.”

Notwithstanding the pressures inherent in making successful presentations before clients, Mr. Rosenshine said he always enjoyed the show.

“I used to love acting out the dialogue in a television ad,” he said. “It was always instructive to see clients’ reactions. I enjoyed the performance. People would tell me that I would have made a good trial lawyer – I think and speak pretty well on my feet.

“There’s been the bit of the ham in me,” Mr. Rosenshine said. “If I have any regrets at all, it’s that I didn’t study acting. But I’d probably have starved in the theater.”

He didn’t entirely abjure acting. For many years he participated in productions staged by a group in Westchester called “The Chappaqua Players.” He played the role of Mordcha the Innkeeper in “Fiddler on the Roof,” the Joseph Stein musical based on the Yiddish short stories by Sholom Aleichem.

If his love for acting spurred him during presentations at BBDO, so did his affinity for writing.

“By the time I graduated from Columbia College with an English literature major, I’d learned to write pretty well,” Mr. Rosenshine said.

His skill fetched him a gig at Brooklyn College, where Mr. Rosenshine taught remedial writing courses, focusing on helping his students to organize their thinking.

His cerebral faculties were tested a notch higher at the job that he took up next.An industrial advertising agency, J.B. Rundle, hired him at $8,500 a year – a princely sum in those days for a young person barely out of college. Among the companies for which he wrote ad copy was United States Rubber.

His clientele grew at BBDO, the next stop for Mr. Rosenshine. The list included Gillette, Pepsi, DuPont, and New York Telephone.

For a man who’d grown up in the Queens neighborhood of Sunnyside Gardens as one of two sons of a pharmacist, Aaron Rosenshine, and a secretary, Anna, advertising was not a planned career.

“When I was growing up,I had no idea what I wanted to do,” Mr. Rosenshine said.”I had no idea what I was good at.”

He discovered he was good at cooking. He’d lost his father at a young age, and Mr. Rosenshine would prepare meat and potato dishes for his working mother and, occasionally, for his older brother, Matthew, who was already at college. He also spent his leisure hours playing ball with his gregarious friends.

“By the time I got to BBDO, I found that I was quite verbal,” Mr. Rosenshine said. “And since I’d had some science at Columbia, I found that the background was useful when it came to translating technical terms into ad copy.”

What proved most useful, however, was what his friend, Mr. Reinhard, characterized as “good judgment and a laser like mind.”

“He’s very practical,” Mr. Reinhard said. “He can cut through dense arguments and get right to the point. … His realism, and sometimes productively cynical attitude, complemented my eternal optimism – perhaps that’s why we’ve worked so well together.”

Such professional harmony isn’t necessarily universal in the competitive cauldron of advertising.

“This business is so ego- and turf driven,” Mr. Rosenshine said. “You cannot trust a lot of people.”

Does he view himself as trustworthy?

“Most people believe that I am trustworthy,” Mr. Rosenshine said. “Have I ever told white lies so as not to hurt someone’s feelings? Of course. But I like to think that I’ve led a life of integrity. This is a people business. You can’t succeed in advertising if the people around you don’t want you to succeed.”

But surely, the reporter said, there was something more than that to explain his extraordinary success.

Mr. Rosenshine smiled.

“For me, it’s combination of intuition and common sense,” he said. “I long ago found that my left brain – the rational side – was more dominant than the emotional right side. So even if I’m not always dealing with people emotionally and in a personal manner, I know that I’m always dealing with them honestly.”

That sensibility extended to his efforts in creating the Partnership for a Drug-Free America. It also perhaps explains his charity work, and his mentorship of young people who seek careers in fields such as advertising.

“I tell them to have fun,” Mr. Rosenshine said. “It’s not a serious business – that’s because there aren’t any metrics to measure success. As long as communication is going to be impacted significantly by emotion, success is going to be very hard to measure.”

And there’s another bit of advice that he likes to impart to young people.

“You’ve got to keep your sense of humor in the ad business,” Mr. Rosenshine said. “You’ll need it.”