Ben Frisch opened his Feb. 14 pre-calculus class at Friends Seminary the same way that he opened all his classes over the course of his 34 years at the private Quaker school in Manhattan: with an invitation to his students to share anything that was on their minds, followed by the gentle ringing of a chime and a long moment of silence. He then introduced the day’s lesson, involving the calculating of angles of depression and elevation. Frisch straightened out his right arm to demonstrate. He lowered it down and then raised it up. Glancing at his arm, now fully extended and pointing slightly upward, Frisch realized something: He was inadvertently pantomiming the Nazi salute. Frisch is a practicing Quaker, but his father was Jewish, and two of his great-grandmothers were killed at Auschwitz. Mortified, he searched for some way to defuse the awkwardness of the moment. And then he said it: “Heil Hitler!”

A few students gasped; others exchanged surprised looks or laughed nervously. Instantly aware that his stab at Mel Brooks-style parody hadn’t landed, Frisch lowered his arm and tried to explain himself, telling his students that it used to be common to make fun of Nazis. Only recently, he said, had such jokes become taboo. He resumed the lesson, and the weird moment seemed to be over.

News of the incident spread quickly. A student mentioned it to Friends’ director of diversity and inclusion, Jason Craige Harris, who in turn told the dean of co-curricular programs, Leitzel Schoen. The following day, Schoen called the school’s principal, Bo Lauder, catching him on a plane to visit a sick relative in Alabama. Lauder decided that Frisch should stay home until the school figured out what to do.

Over the following days, Lauder heard from dozens of parents. Many expressed support for a teacher they considered a pillar of the Friends community. Others said they thought the “Heil Hitler” gesture inexcusable, a few going so far as to say that if Lauder did not take action, they would withdraw their children from the school. At a meeting with administrators about the incident in late February, members of the high school’s Parents Association said that keeping Frisch would send the message that the school didn’t take anti-Semitism seriously. Another parent told Lauder that this was not the first time Frisch had said or done something inappropriate.

Twelve days after the “Heil Hitler,” Lauder and several members of the school’s board called Frisch in for a meeting at the school. To resolve the situation, they said, Frisch had to go. They gave him a choice: He could either resign or be terminated. It was Lauder’s hope that Frisch would decide to resign and accept a settlement that would include a severance package and a nondisclosure agreement. After nine days of failed negotiations, Frisch chose instead to be fired. With the backing of the Friends Seminary Teachers’ Association — Friends is one of only a handful of private schools in New York City whose faculty is unionized — he opened a grievance process against the school, arguing that he had been wrongfully terminated. He would have the chance to argue his case for reinstatement at an arbitration hearing scheduled to take place near the end of summer.

A button worn by students in support of Ben Frisch. Sarah Anne Ward for The New York Times

Lauder sent a letter to teachers, parents and alumni on March 9, hours after the school emptied out for spring break, informing them of the news. He described the “Heil Hitler” salute and alluded to “other equally inappropriate and troubling actions” that had surfaced since the incident, without providing any details about them. “When I made the decision, I knew it could cause the ceiling to come crashing down,” Lauder told me. “But I had to act on what I thought would be best for the school and the students.”

The concepts of “safe spaces” and “trigger warnings,” hotly debated on college campuses for years, are now reaching high schools too. It’s easy enough to say that college students are supposed to have their assumptions challenged daily, even if that sometimes means experiencing discomfort. But the question of what high school students should be exposed to, and protected from, feels murkier in 2018. Today’s high school students are more precocious, more politically engaged, more tuned in to their gender identities and nascent sexuality. They are already flooded with uncensored, unedited information, 24 hours a day: What would a safe space even look like for a 16-year-old with an iPhone? At exclusive private schools like Friends, the question is further complicated by the involvement of wealthy parents. As these schools have grown more expensive — Friends costs nearly $50,000 a year — administrators have found themselves trying to balance their own institutional values with the demands of parents who are in a sense high-paying customers. Teachers are increasingly caught between the two.

Pedagogy at the high school level is inherently personal. But when the lines of appropriate discourse are continually being redrawn, it is also inherently risky. The job of high school teachers is to impart knowledge and deliver measurable results, which requires finding a way to reach, and ideally even inspire, their students. “How would you keep the attention of 15 teenagers and bond with them?” one Friends teacher texted me, insisting on anonymity because of a school policy that discourages teachers from speaking to the media without permission. “You MUST joke and be yourself and connect with them on their terms. It’s the only way to be good at this.”

Frisch’s former students describe him as eccentric, nerdy, prone to lengthy classroom digressions about his stamp collection, dinosaurs or childhood snow days spent sledding. Any teacher who spends three decades in the classroom, speaking extemporaneously for hours on end to a roomful of teenagers, is going to have awkward moments. Frisch might have had more of them, and they may have been a bit more awkward. But that was how he connected, and it was perhaps a way of connecting that is no longer possible. “Everybody knew this guy was off — weird behavior, quirky,” said one parent who, fearing retribution against her child, insisted on anonymity. “Maybe in the ’70s that would have been O.K., but not when you’re paying $45,000 a year in tuition.”

What can teachers say or do now? Who gets to decide when they’ve gone too far and how severe the punishment should be? As the spring semester went on, the history of Friends Seminary made these questions especially charged. Located on East 16th Street, on a quiet, elm-shaded block that dead-ends at Stuyvesant Square Park, the school was opened in 1786, at a time when America’s Quakers, having fled religious persecution in England, were helping to shape a more tolerant set of founding principles for a new nation: The Bill of Rights was modeled after the original Pennsylvania charter, which was drafted by a Quaker, William Penn.

Friends’ original intent was to provide a “guarded education” to Quaker children. There were to be no frivolous pursuits: only reading, writing, basic arithmetic and Bible study. Like other Quaker schools, Friends eventually opened its doors to the general population and broadened its educational mission, while aspiring to remain true to Quaker values like equality, simplicity and community, and to the overarching Quaker duty to build a better society. As it evolved, the school’s proximity to Greenwich Village made it a popular choice for artists, writers and liberal activists. The pacifist and perennial Socialist Party presidential candidate Norman Thomas sent his daughter to Friends; Eleanor Roosevelt and John Lennon spoke to students in its 19th-century red-brick Quaker meetinghouse, which still serves as the primary gathering space for assemblies, musical performances and the school’s weekly Quaker “meetings for worship.” Every night, a common area off the school’s lobby is transformed into a 14-cot homeless shelter run by members of the nearby Quaker congregation with the help of faculty and parent volunteers; on Fridays, the school’s second graders make baked goods for its residents.

In recent years, the demographics of the school have shifted with those of the city. As the rich have grown richer, couples who would once have left for bigger houses and better schools in the suburbs when they had children are now simply buying bigger apartments and sending their children to private schools. There aren’t enough seats in the historically more desirable uptown institutions — Spence, Dalton, Trinity — to meet demand; and for families who live in neighborhoods like the Village, TriBeCa or Battery Park, Friends is a much more convenient option. Friends now sees itself as a competitor to these schools, and in some respects, it has become indistinguishable from them.

For much of the school’s history, its finances were precarious, in part because Quakers frown on hoarding wealth. Lauder has tapped into the new money flowing into the school, courting wealthy families at private dinners and fund-raising events. Tuition has more than doubled since Lauder’s arrival. In 16 years, he has increased the school’s endowment to $30 million from $4 million, and raised $47 million for a $72 million renovation that is halfway to completion: The school is gutting three townhouses, connecting them to its main building and adding new floors and a rooftop greenhouse. This year, its annual auction, which once took place in a nearby church and featured homemade quilts, was held in the ballroom of a luxury hotel and included an Ellsworth Kelly painting and a screening party at Soho House with the actor Kyle MacLachlan.

Most Quaker schools incorporated independently years ago. But until recently, Friends and the organization that oversees Manhattan’s Quaker community, the New York Quarterly Meeting, were essentially a single entity. Last year, they finally separated, the culmination of a protracted, often contentious legal process. Under the final agreement, Friends became a long-term tenant of the Quakers and now pays the Quarterly Meeting roughly $1 million a year in rent, or about a third of market rate. Friends also committed to following a detailed set of principles in order to remain a Quaker school, a status that is central to its brand appeal.

Even before Frisch’s termination, there was a feeling among some in the Friends community — parents, teachers and especially alumni — that in its race to keep pace with a changing city, the school was losing touch with the Quaker ethos that had long distinguished it. Perhaps inevitably, the fight over Frisch’s termination became a proxy battle in this larger war: Frisch was the only Quaker teacher in the high school. What is more, the manner in which the school fired him bore little resemblance to the Quaker decision-making process, which calls for the participation of the entire community in open dialogue. “What has made Friends a special school is the Quaker values, and that’s what has been broken in this process,” says Jacques Lilly, a longtime Friends parent. “What do you have if you don’t have those? You’ve got a nice, second-tier, expensive New York City private school. Why don’t you send your kids to Brearley instead?”

Days after the “Heil Hitler” incident, the administration gathered Friends’ 279 high schoolers in the meetinghouse to inform them that Frisch had been suspended. It was the first time that some students had heard about the incident, and a number were vocal about their view that it didn’t merit disciplinary action. “It got ugly pretty quickly,” recalls Abraham Levin, who was a senior at the time. One student pointed out that Lauder had uttered insensitive things, too: Just a few months earlier, while talking about the school’s fund-raising efforts, he said that all-girls schools typically have an easier time building their endowments, because men die younger and leave their money to their wives. (Lauder says that he was describing a phenomenon that was well known within the private-school community but that he should have been more careful in explaining it.) A few days later, Levin and a couple of his classmates taped a petition to Lauder’s door signed by 187 students, urging the school not to terminate Frisch. “We are petitioning because we are afraid the controversy surrounding Ben’s mistake will result in his firing, and we believe this would be an immense loss for our community that would only increase the upset within the student body and faculty,” it read. “We understand that there are likely others with more influence who are pushing you in the opposite direction, but we hope this petition will encourage you to consider our perspective.”

Word of the firing spread quickly over spring break, and when classes resumed in late March the school erupted in protest. Students were angry that they had no voice in the process and that the school had not shared with them any details of the other “equally troubling incidents” that informed its decision. They staged a sit-in that spilled out of Lauder’s office and into the hallway outside and walked out of meetings for worship carrying protest signs: “Free Ben Frisch,” “Make Friends Quaker Again,” “Bo Chi Minh.” Students wore “Bring Back Ben” buttons around campus and reflected on the case in classroom essays, applying the teachings of Mahatma Gandhi to Frisch’s situation and comparing the fight on his behalf to the Dakota Pipeline protest at Standing Rock. In a commencement address, the senior Benjamin Levine offered a thinly veiled critique of the administration: “It’s so much easier and simpler to decide someone is racist or ignorant or naïve — or anti-Semitic — than to engage in the messy work of trying to communicate and understand when conflicts arise.”

Alumni took to an unofficial Friends alumni Facebook page to express their anger and disappointment, producing long threads about the dangers of speech codes, about the history of Jewish humor as a means for dealing with tragedy, about the transformation of Friends “from a haven of progressivism, compassion and common sense into a corporate, ‘liberal’ and truly luxe institution.” Twenty-six former teachers and administrators, including Lauder’s predecessor as principal, signed a public letter calling for Frisch’s immediate reinstatement. Philip Schwartz, a popular English and Latin teacher who retired in 2014 after 48 years at Friends, wrote a letter to the school, asking that his name be removed from its list of emeritus faculty members. He accused Friends of “capsizing into the swamp of political correctness” and observed that “a dialogue of reconciliation and tolerance no longer seems to be our Quaker core value.”

And yet as the protests gathered momentum, they started to present their own challenge to the spirit of dialogue and tolerance. The overwhelming majority of students, teachers and alumni disapproved of Frisch’s firing, while those who did believe that the “Heil Hitler” was unforgivably offensive or were inclined to respect the administration’s decision to withhold details of a sensitive employment decision kept their opinions to themselves. For some, the fight for free expression had become repressive in its own right.

In April, the co-editors of the school newspaper, Camilo Durr and Maeve Woollen, showed Lauder a draft of a special issue about the Frisch controversy. Lauder passed it on to Will Hopkins, the interim head of the upper school, and Erica Jones, the dean of students. The administrators expressed disappointment that none of the articles were sympathetic to the school. Hopkins encouraged Durr and Woollen to include a wider range of opinions, suggesting that they go beyond the newspaper staff and solicit articles from the broader community. After a couple of weeks, the editors started to think the administration was just stalling. “They said later that they supported us, but it was clear from the atmosphere that they didn’t want the issue to come out,” Durr told me. After attending an emotional, communitywide Quaker meeting about Frisch at the meetinghouse, he and Woollen emailed PDFs of the paper to the student body, faculty and administration. Both editors were removed from their jobs: “digital misconduct” was the charge. “I felt like they walked away from the community process,” Hopkins told me.

Benjamin Levine, Abraham Levin, Camilo Durr and Maeve Woollen, all recent graduates of Friends Seminary, at Stuyvesant Square Park. Elizabeth Bick for The New York Times

New York’s Quaker community, which numbers about 500, was furious about the school’s treatment of a longtime member. They came together at their various meetinghouses around the city to draft “minutes of concern” about the firing, asking the school to explain how its handling of Frisch’s case was consistent with Quaker values and calling instead for “restorative justice,” a process whereby perpetrators, victims and community members meet to collectively decide how to repair the harm caused by an offense. “I have never seen such unity among Quakers,” Charles Brainard, an 85-year-old lawyer and worshiper at the Friends meetinghouse, told me. “Bo is just a very ambitious guy, and he was out to build this primo school, and I don’t think that truth sank into many Quakers until Ben Frisch was fired.”

Bo Lauder came to Friends in 2002 from another Quaker school, Sidwell Friends, in Washington, D.C. — attended by the children of presidents from Theodore Roosevelt to Barack Obama — where he had run the upper school. Lauder, who is 57, wears bow ties and round-framed, tortoiseshell glasses. He grew up in a small town outside Montgomery, Ala., and studied musicology at the University of North Carolina before going into secondary-school administration. Sitting in his office at Friends on a recent afternoon, he told me that he believed he was the first openly gay head of a private school in New York City, and that he was still grateful to the predominantly Quaker search committee for hiring him.

Lauder is unapologetic about his aspirations for Friends. He said that he undertook the current renovation specifically to bolster the school’s appeal to the city’s best private-school students, even though it required him to spend much more time than he would have liked talking to bankers about the school’s asset-to-debt ratio and in lawyers’ offices negotiating the separation from the Quakers. But he also told me that he believes he has strengthened the school’s commitment to its Quaker heritage: During his tenure, Friends created its own Center for Peace, Equity and Justice, which hosts an annual Peace Week, with guest speakers like Chelsea Clinton and the Columbia University economist Jeffrey Sachs.

At the end of what had been a very tumultuous school year, the board — half of which is appointed by Quakers and otherwise includes an assortment of parents and alumni — sent out a letter to the community expressing its confidence in Lauder. But his support among much of the faculty seems shaky at best: The teachers’ union recently sent the trustees a letter signed by 72 of its 96 members (18 abstained) describing morale as “perilously low” and saying that they felt “silenced or scolded” by Lauder and were “losing faith in his leadership.”

Lauder said his job has changed immeasurably since he arrived at Friends. “Starting now in my 17th year, I feel like I was Mr. Rogers in Year 1,” he told me. He is now trying to juggle the demands of running a competitive and pricey Manhattan private school with an institutional culture that empowers community members to not only raise their voices but to expect to be heard. The school’s Quaker identity calls for it to be faithful to its progressive tradition, but in the new age of identity politics, it is not always easy to know what the right stance on a particular issue should be. Just a few months before the Frisch incident, some 20 parents had raised questions about the scheduled speaking engagement of a visiting scholar, Dave Zirin, a sportswriter for the Nation magazine and a Friends alumnus who had been critical of Israel in his writings. In 2012, there were heated objections to a musical performance in the meetinghouse by Gilad Atzmon, an Israel-born saxophonist and self-described “proud, self-hating Jew” who has written that Palestinians were “brutally ethnically cleansed” and suggested that if Israel starts a nuclear war with Iran, “some may be bold enough to argue that Hitler might have been right after all.” The Harvard Law School professor emeritus and noted gadfly Alan Dershowitz publicly criticized Friends — and Lauder personally — for refusing to cancel the appearance.

Lauder did not consider the “Heil Hitler” episode a close call. “Personally, I was appalled,” he told me. “I couldn’t imagine, even as a joke — and I grew up watching ‘Hogan’s Heroes’ — that in a class that had nothing to do with history or World War II or Nazism or teaching German language that an incident like that could happen.” I asked Lauder why he felt he needed to go so far as to fire Frisch. “One of our pledges is to make all of our students feel safe,” he replied. “And that is something that I take very, very seriously.”

That no one has accused Frisch of being an anti-Semite was beside the point: His invocation of the Nazi salute in a classroom full of high school students, regardless of his intentions, was enough to end his career. On today’s campus, words and symbols can be seen as a form of violence; to many people, engaging in a public debate about the nuances of their power is to tolerate their use. “I asked one of our lawyers, ‘How can I do this in a more Quakerly way?’ ” Lauder told me. “And he just looked at me and stated the obvious: There is no way to make a firing a Quakerly event.”

On Aug. 14, Frisch, Lauder and a small procession of lawyers, administrators, faculty members and recent alumni filed into a large conference room in an office building in Midtown Manhattan for the arbitration hearing.

For months, rumors circulated about what Frisch’s “equally troubling incidents” might be. Now the school presented two witnesses, both former Friends students, to describe them. One remembered Frisch sarcastically telling a classmate of hers who had gotten a math problem wrong that he should “go outside and kill himself.” The other testified that Frisch had stroked her upper arm with his finger in the classroom in a way that made her feel uncomfortable and that he had moved his chair so close to hers during a tutoring session in the math-department office that their bodies were touching. (Frisch’s lawyer asked her if she was aware that he wore hearing aids.) The witness had dismissed the incidents at the time but was reminded of them when she was contacted by the school’s diversity director, Harris, who led the Frisch investigation. Frisch, who first learned about the claims after his termination, denied ever having told a student to kill himself and said that he had no memory of the inappropriate touching that had been described.

Frisch’s lawyer called a member of the February pre-calculus class who has since graduated, Josie Girand, to testify about the “Heil Hitler” incident. She recounted Frisch’s actions and described her reaction to them, acknowledging that it was an awkward moment, but adding that she hadn’t thought it was a big deal at the time. When Frisch’s lawyer asked Girand if anyone she knew had been offended by the gesture, the school’s lawyer objected.

The hearing, which was closed to the public — I had to rely on secondhand accounts — lasted a little more than five hours. The arbitrator will decide in the coming weeks to uphold the termination or to order the school to reinstate Frisch.

A few days after the hearing, Frisch opened the door of his home in Brooklyn in a short-sleeved shirt, khaki shorts and bare feet. He told me about his family background. Frisch is a direct descendant, he said, on his mother’s side, of John Bowne, a Quaker legend who in the 17th century helped lead the fight for religious liberty in America. His father was a scientist at Bell Labs and a professor at the State University of New York. Frisch grew up Quaker on the edge of a farm in upstate New York and attended a Quaker college, Haverford. He told me that he never intended to become a teacher. When he came to Friends in 1984, he was planning to stay only a year before returning to Caltech to complete his Ph.D. in geochemistry. He eventually became a Friends parent, too; he and his wife sent both of their children, who are now out of college, to the school.

Frisch enjoyed an exalted status at Friends that flowed from his years of service to the school and, above all, his Quaker faith. Every year, he helped lead a three-day retreat for graduating seniors at Powell House, a Quaker conference center in upstate New York, where he would tell outgoing students that even though they were leaving the school, the doors of the meetinghouse would always be open to them. Even as the controversy over his firing was unfolding, a brief tribute to Frisch was on display in the school’s lobby — alongside one to the civil rights leader Bayard Rustin and another to William Penn — written by a Friends first grader, part of a class project honoring important Quaker activists.

Frisch would not discuss the two other claims, but we spoke at length about the “Heil Hitler.” Frisch said he was embarrassed, both by the fact that he had made the gesture in the first place and by his subsequent failure to recognize the seriousness of such a lapse in judgment. But he was also surprised by the school’s reaction to it. “I trusted while I was at Friends that because of my long-term commitment to the school, that as I need to change to meet the changing dynamics of the classroom, the school would help me learn and provide the support I needed to make those changes,” he told me.

The dynamics of the classroom are changing. These changes are partly specific to the hothouse environment of the campus in 2018. But they also connect to something much bigger. High schools have become genuinely unsafe: The “Heil Hitler” salute happened on the very same day as the Parkland massacre. And beyond the confines of the campus, a crude, violent bigotry that had long seemed part of the distant past has suddenly resurfaced, with neo-Nazis literally marching in the streets. The question now is what do we want our response to this new world to be. During the 12 days that he spent in limbo between his suspension and termination, Frisch, in the spirit of the Quaker commitment to reconciliation, drafted a letter of apology to his students that he was never allowed to send. Among other things, he planned to say that he was worried about the rise of anti-Semitism and that he was still learning lessons from his mistake. “You think about things like Charlottesville,” he told me. “Now, we don’t make jokes like this.”