There is no escaping them. They have left their mark everywhere in Israel, in the form of a cryptic mantra painted in bold Hebrew lettering on security fences, sleek skyscrapers, graveyard walls, freeway billboards and sheer mountain cliffs.

Dressed in characteristic woven white skullcaps, adherents perform leaping dances on street corners in the secular bastion of Tel Aviv, to techno-Hassidic music blasting from vans bearing the slogan "Na Nach Nachma Nachman Me'uman," which has informally lent its name to the newest of Hasidic sects.

The Na Nachs, as some of the group call themselves, are an offshoot of the Bratslav Hassidim, followers of the late Rebbe Nachman (1772-1810), great-grandson of the founder of Hasidism. But what separates Na Nachs from other Bratslavers is their belief that a mysterious letter found in 1962 by Rabbi Israel Dov Odesser, a Bratslaver Hasid from Tiberias, was a miraculous message from Rebbe Nachman himself, and that the mantra it contained, which mentioned Nachman and his burial place, Uman, Ukraine, was a "Letter from Heaven."

All other Bratslaver groups reject the validity of the letter. But this does not deter Na Nachs from believing it to be "the new song through which all of Israel will be redeemed."

Among them is Shmuel David Ravitch, born in Philadelphia, Pennsylvania into what he calls a "normal Jewish house." His family was secular, but observed the holidays. In 1990, Ravitcher became religious, ultimately spending 13 years with Chabad. But he came to find the Chabad experience unsatisfying.

Oddly enough, given the uniquely Israeli roots of the Na Nachs, it was in Chicago that Ravitch was first introduced to them. "We met a guy who came to America to meet a girl in Chicago. He was Na Nach, and he started to tell us about Na Nach," Ravitch recalls.

"I already knew, because I was in Uman before, but he told us more. One day at Purim time we saw the guys in the van. We were curious and we ran after the van. And they asked 'Hey, do you want to come with us.' And I did. And that was my education."

For others, the brightly colored vans were their introduction to Na Nach. Adorned in stickers bearing the picture of Rabbi Odesser and covered in large decals of the mantra, the vans have been key to attracting new devotees.

For onetime Eliezer Grunwald, born into a Hasidic family in Monsey, New York, an encounter with a Na Nach van crew played an intrinsic role in his conversion. Grunwald had attended yeshiva, where, he said, he had merely gone through the motions to keep his family happy. He was more interested in partying than Torah.

After a while, he felt like he "was wasting his time in America." All his friends started going to Israel, so he decided to follow suit. In Israel his life soon began to revolve around partying and playing in rock bands. It wasn't long before the novelty began to wear off. His mundane routine wore on and on, until one night when he saw the van.

Grunwald was intrigued by the dancing Na Nachs and decided to start dancing right alongside them. "I saw them every night," Grunwald said. Over time, he began to acquire a large collection of Na Nach literature which he procured from the van. It was the literature that he obtained from the van that would spark the transformation in his life.

After a long night of partying, he returned home drunk and depressed. In desperation, he reached for a random title from his bookshelf and opened it up. He looked at the random passage which said, "you're a sinner, but G-d still loves you." After that, he began to open up, he says, and has been Na Nach ever since. That was six years ago.

He decided to stay in Israel for good and now lives in Safed with his wife.

For secular onlookers, the vans and their broadly smiling crewmen evoke mixed reactions, often negative when the Na Nachs are nowhere in sight.

"They are crazy, they stop in the middle of the highway they put their car in the middle of the highway and get out and start dancing," comments one bystander.

"They are good people, but they are all crazy," concludes another.

When the van is present, however, onlookers' expressed perceptions often tend to be more accepting.

"It's good, they bring the Torah and people to the religion."

"They're the most amazing guys I ever heard about."

"It's just funny, it's just nice."

The vans belong to the Keren, which is the organization that prints the books of Rebbe Nachman and Rabbi Odesser. All gasoline is paid for by the Keren with the money that is made from the books which are sold at cost. The van serves two functions. The first is to spread the message through literature. Na Nachs can be seen regularly on street corners, music blaring, standing next to a table full of books.

The second stated function is to drive around and dance to spread joy to the people. This is the most well known and also the most crowd pleasing. Both types of "missions" are referred to as a haftza, a Hebrew-derived expression denoting "spreading," and participation is strictly on a volunteer basis. In recent observations, the van crews appear to be succeeding in their mission of spreading joy. Many observers who are not Na Nach can often be seen joining in the dancing.

Even when no van is near, public opinion can be in their favor. "They can keep dancing, it's fun," remarks Liron Slonimsky. "They put some life spirit in the streets."

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