The death today of the Novominsker rebbe, Rabbi Yaakov Perlow, will lend a sad note to the Passover seders of tens of thousands of families the world over. The rabbi, a towering figure in the world of Torah Judaism, was carried off from his home in Brooklyn by the coronavirus. He perished at 89, two weeks after issuing an important warning to Jews that religious law required them to heed medical doctors during the pandemic.

We did not know Rabbi Perlow personally, though we’d once met him briefly at the offices of the Agudath Israel of America. We admired him enormously for setting a standard to which fervently orthodox Jews could repair. The Aguda is the largest grassroots organization of fervently religious Jews. Rabbi Perlow had been its president since 1998 and also chaired its Council of Torah Sages.

The Novominsker dynasty that Perlow headed was founded in Poland by his grandfather and later headed by his father, whom Perlow succeeded. In 2015, at the Aguda’s annual banquet at the Hilton in New York, Rabbi Perlow surprised attendees by suddenly declaring he felt “compelled to address the president of this great country,” meaning President Obama. Yeshiva World reported that a “deafening silence” came over the hall.

Rabbi Perlow proceeded to voice his movement’s concerns over the impending pact with Iran. He invoked the 70th anniversary of the Holocaust and then appealed to Mr. Obama to “rise to the challenge of history.” Yet, by our lights, the signal achievement of Rabbi Perlow’s life is that at a time of Jewish assimilation and retreat in many spheres, he led a vast movement of fundamentalist Judaism that is booming.

We last marked this point in an editorial called “Rock of Ages, Indeed.” It was about how, on January 1, close to a hundred thousand fervently religious Jews, gathered by the Aguda, would be filling MetLife Stadium for the reading of the final page of a seven and a half year cycle of study of the biblical commentaries known as the Talmud. Perlow, the Forward reported, devoted his remarks to the centrality of study.

That is something to think about as a pandemic has forced nearly half of humanity into their homes, where millions are wondering what the future will hold. Perlow’s funeral today was attended personally by only a tiny contingent of family and a few others closest to him. Yet thousands followed via a telephone hookup so they could share in the prayers for a modest and modern man who emerged as a leader by hewing to the Torah given more than three millennia ago.