In the 1980s, the legendary scholar Alexander Altmann produced a new edition of Jerusalem, the 18th-century German Jewish philosopher Moses Mendelssohn’s major work on Judaism and religious tolerance, and asked Allan Arkush to provide an English translation. Arkush reminisces about working with Altmann, an archetypal German Jew with vast knowledge and unfailing punctuality, and seeks to explain why he devoted so much of his career to Mendelssohn, a figure often derided or dismissed by Jewish thinkers:

The other day I took [Altmann’s] The Meaning of Jewish Existence: Theological Essays 1930–1939, a book published four years after his death, off my shelf. It was a humbling experience. When Altmann wrote these essays, he was younger than I had been when I translated Jerusalem. But not then and, I’m afraid I have to admit, not even today could I pretend to possess anything remotely like his mastery of Jewish sources and contemporary philosophy. My friends and I often lament the lack of cultural literacy of many of the students who show up in our university classrooms. But the gap between them and what we were like at their age is surely smaller than the one that separated our younger selves from even the run-of-the-mill yeshivah and Gymnasium graduates who showed up in German universities in the early 20th century—let alone a figure like the young Alexander Altmann, who never stopped learning.

One thing that struck me as I reread The Meaning of Jewish Existence was the near absence of Moses Mendelssohn from the volume. It wasn’t, in fact, until after World War II that Altmann began to devote his immense energies to researching the historical figure about whom he would publish voluminously and with whom his name is now most closely associated.

In an illuminating introduction to the essays, [the scholar Paul] Mendes-Flohr describes how beset young Alexander Altmann had been by “the emergence of an ominous nihilism” in the years after World War I and how much his own early philosophical efforts constituted an attempt to combat it.

It seems that in the aftermath of the next world war, Altmann took a different tack in his battle against nihilism. He devoted himself to the intense study of a pioneering modern Jewish thinker who had lived a noble life, a man whose unshaken confidence in the existence of God, providence, and immortality could continue to inspire us, if not necessarily convince us that the philosophy to which he adhered was a true one.

Two extraordinary events demonstrate something important about Israel’s most fervent adversaries. One was a speech given at something called The People’s Forum (funded generously by Goldman Sachs), which stated, “When the state of Israel is finally destroyed and erased from history, that will be the single most important blow we can give to destroying capitalism and imperialism.”

The suggestion that this tiny state is the linchpin of a global, centuries-old phenomenon like capitalism goes well beyond anything resembling rational criticism. Even if Israel were guilty of genocide, apartheid, and oppression—which of course it is not—it would not follow that its destruction would help end capitalism or imperialism.

The other was an anti-Israel protest that took place in front of New York City’s Memorial Sloan Kettering Cancer Center, deemed “complicit” in Israel’s evils. At organizers’ urging, participants shouted their slogans at kids in the cancer ward, who were watching from the windows. Given Hamas’s indifference toward the lives of Gazan children, such callousness toward non-Palestinian children from Hamas’s Western allies shouldn’t be surprising. The protest—like the abovementioned speech—deliberately conveyed the message that Israel is the ultimate evil and its destruction the ultimate good, cancer patients be damned.

The fact that Israel’s adversaries are almost comically perverse does not mean that they can be dismissed. If its allies fail to understand the obsessive and irrational hatred that it faces, they cannot effectively help it defend itself.