Founded in Vilna in 1925, the Jewish Research Institute (known by the Yiddish acronym YIVO) was dedicated to studying, and later to preserving, East European Jewish life and the Yiddish language. It relocated to New York City during World War II, and in the early 1960s several of its original members remained actively involved. In his diary from that decade, Ezekiel Lifschitz—then YIVO’s chief archivist—recorded, inter alia, the visits to the institution of three luminaries of Jewish literature: the Yiddish poet Avraham Sutzkever, the English-language novelist Saul Bellow, and the Hebrew writer S.Y. Agnon.
Cecile Kuznitz, who translated the excerpts describing these encounters, explains why Bellow was interested in the work of one particular Yiddish-language scholar:
The occasion for Bellow’s  visit was a meeting with the historian Isaiah Trunk, a YIVO staff member. Trunk, a critic of Hannah Arendt’s caustic appraisal of the Nazi-created Jewish councils, published a study of the Łódź Ghetto in 1962. Bellow was presumably gathering material for his next novel, Mr. Sammler’s Planet , which includes lengthy reflections on the Holocaust.
The protagonist of Mr. Sammler’s Planet critiques Arendt’s concept of “the banality of evil” and offers his thoughts on Chaim Mordechai Rumkowski, the controversial head of the Jewish council in the Łódź Ghetto. In fact, Sammler is the author of an “article about that crazy character from Lodz—King Rumkowski,” whom he describes as “a mad Jewish King presiding over the death of half a million people. . . . Rumkowski, King of rags and shit, Rumkowski, ruler of corpses.” However derisive this language, we learn that Bellow was familiar with Trunk’s nuanced account of the impossible choices facing the heads of the Jewish councils.
Lifschitz describes the visit thus:
Bellow visited YIVO today. Apparently he became interested in the Łódź Ghetto and got a copy of Trunk’s book Lodzher geto. Today he came to see Trunk. B. makes a very agreeable impression: natural in his behavior and without “artificial” pretensions. While speaking he easily switched over to Yiddish and although he apologized for his weak Yiddish, it was in fact a surprise how freely he speaks and without a trace of the well-known American accent. While talking I remarked that it’s a quite a distance from [his 1953 The Adventures of] Augie March to [his 1963] Herzog. He replied, “I returned late to Jewish life.” However, he defended Augie March, saying that the book reflected life at the time 30 years ago. I reminded him of the scene in Herzog that moved me greatly, where the protagonist says to his friend more or less: We are already old Jews, let’s become worshippers in the little immigrant shul on our old block. To that Bellow answered, “Where can you find such a little shul now?”