Yom Kippur, the Day of Atonement, is the most important day of the Jewish calendar. It begins Friday at sundown, and millions of Jews around the world will greet the holiday by attending Kol Nidrei, or All Vows, services.

Despite being one of the most famous prayers of Jewish liturgy, Kol Nidrei's wording isn't quite as awe-inspiring as its reputation. Phillip Katz, an adjunct assistant professor at Manhattan College who teaches about world religions, says the prayer "consists of a statement nullifying all vows future or past, followed by a standard list of Aramaic terms for vows."

When you think about it, that's appropriate coming after the mayoral primary, when candidates made far-reaching promises about their visions for the city.

Vows bandied about include Bill de Blasio's Robin Hoodesque approach to early childhood education: taxing the upper echelons to fund school programs. Joe Lhota's promises include a post-recession revival of the American dream and reunifying the city.

Is either realistic? Jamie McKown, who teaches government at the College of the Atlantic, thinks that as a culture we give politicians a hard time about campaign promises. In an email, he wrote, "We complain that politicians don't compromise and work with each other. Then we complain when they compromise and work with each other and call it going back on promises."

But some promises were made to be broken. In fact, some religious scholars believe Kol Nidrei was popularized by Jews as almost an advance apology for being forced to convert to Christianity during the Spanish Inquisition. This way they could make it clear at least once a year that though they'd converted under pain of death, they retained their true faith.

Kol Nidrei has a strong place in popular culture as well. It was made famous in America as a song sung by Al Jolson, and covered by Perry Como and Johnny Mathis. There have been recordings by Southern fiddlers and arrangements for the sitar.

As for political promises not kept, Katz says, "I don't think it's a dishonest thing -- I think it's a politic way of doing things." Perhaps on some level then, Kol Nidrei is the perfect prayer for politicians of every generation, faith and background.

Rachel Weingarten of Brooklyn is author of the forthcoming book "Ancient Prayer: Channeling Your Faith 365 Days of the Year."