When Jews in New York gather tonight to begin observing Yom Kippur, the holiest day of the Jewish year, an unlikely couple of them will be praying together on West 84th Street in Manhattan.

One is 81 years old, an Orthodox rabbi with a white beard who grew up in Poland and in what became Israel. The other is 53, clean-shaven, an American-born writer; he describes himself as having forgotten most of what he learned at the Hebrew school he attended growing up as a Conservative Jew in Wisconsin.

The rabbi, Haskel Besser, is the subject of a book by the writer, Warren Kozak. The book is called “The Rabbi of 84th Street: The Extraordinary Life of Haskel Besser,” and it was published this year by Harper-Collins.

When I sit down with the two of them, Rabbi Besser protests the title of the book. “I don’t consider myself extraordinary,” he says.

One of the extraordinary things about New York is that people who would be considered extraordinary anywhere else are considered ordinary here. But Mr. Kozak’s book and a few minutes with Rabbi Besser in person demonstrate that there’s at least a strong case to be made here for extraordinary.

He managed to escape the Nazis in September 1939. He was in Israel as the Jewish state was being founded. He has been a guest at the White House and is a friend of the president of Poland. He wakes up at 4:30 each morning to prepare for a daily Talmud class he teaches. He reads a half dozen newspapers a day, in English, Polish, Hebrew. As chairman of Poland for the Ronald Lauder Foundation, he has helped to revive Judaism in Eastern Europe. He’s forged a close working relationship with Mr.

Lauder, the businessman, Jewish leader, art collector, advocate of term limits, and former American ambassador to Austria who is the son of Estee Lauder, late founder of the giant cosmetics company.

When I ask the rabbi if, at age 81, he has considered retiring, he scoffs.

“What do you mean I should retire?” he says. “Whoever doesn’t have to retire shouldn’t.” Work, he says, “keeps you fit – not only physically.”

Yom Kippur is a day of atonement. Mr. Kozak’s book describes the rabbi as such a wonderful man that I wonder what sins the rabbi has to atone for.

“I have so much to atone for,” he says, noting that Jews are a people prone to self-criticism.

Then he tells a story relating to the custom Jews have of going to a body of water before Yom Kippur and literally casting out their sins – or some symbolic bread or pocket lint – into the water. He says that 200 years ago, after a group of Jews including a great rabbi had returned from carrying out this casting away of sins, they saw another Jew running toward the river. The group of Jews asked him where he was going. “To pick up my rabbi’s sins,” he said.

The point is that a righteous man’s sins are something that other people might consider themselves fortunate to have. “It’s all relative,” Rabbi Besser says. For some people, a sin to atone for on Yom Kippur might be “something very terrible.” Others might be atoning for “one doubtful moment.”

Rabbi Besser says that one reason he cooperated with the book is that people have wrong impressions of Orthodox rabbis. “The world should see that we are just normal people like others,” he says.

Mr. Kozak – without conceding that Rabbi Besser is just normal – acknowledges that one reason he wrote the book was to puncture stereotypes. “I have a lot of friends who are very anti-religious and anti-Orthodox, and a lot of them happen to be Jewish,” he says.

Messrs. Kozak and Lauder celebrated the publication of their book with a party at the Neue Galerie, the museum of German and Austrian art that was founded by Mr. Lauder and is housed on Fifth Avenue in what was the mansion of Mrs. Cornelius Vanderbilt III.

Tonight, as Yom Kippur begins, this unlikely pair of friends will be in a less formal setting, the small house of worship on West 84th Street known, after its rabbi, as the Besser Shtibl.

“You know the difference between a synagogue and a shtibl?” Rabbi Besser asks. “A synagogue has decorum. A shtibl is just the opposite.”

In his shtibl, he says, people greet each other and interact. He says, “It takes away, perhaps, from the solemnity of the service, but it adds in warmth.”