Harry Kemelman’s Nicky Welt stories herald a revival in detective fiction, where the intellectual prowess of the armchair detective takes center stage. Nicky Welt, an enigmatic character, approaches crime-solving with the same precision he applies to chess problems, driven by a desire to showcase his logical acumen for personal amusement. Unlike traditional detectives concerned with morality or justice, Welt is more interested in exhibiting his mental superiority, particularly over his closest confidant, the nameless narrator. This unnamed narrator, who introduces himself as a Fairfield County attorney and a former law-school faculty colleague of Nicky’s, plays the role of the faithful “Watson” in their dynamic, underscoring Welt's intellectual dominance.

While the Nicky Welt series is both clever and entertaining in its own right, its true significance lies in paving the way for the Rabbi David Small series. Kemelman himself noted, “Rabbi David Small can be said to be the son of Professor Nicholas Welt.” In this sense, Rabbi Small inherits Welt's methodology of logical deduction, albeit with a shift in focus. Unlike Welt’s chess-based logic, Rabbi Small’s reasoning is rooted in pilpul, a meticulous form of analysis taught in yeshivas for interpreting the Talmud, the Jewish oral law that provides commentary on the Torah. This approach not only serves as the foundation for solving mysteries but also transforms the narratives into lessons on ancient Judaic traditions and contemporary Jewish sociology. As critic Anthony Boucher described it, the series functions as “a primer to instruct the Gentiles.”

Rabbi Small’s involvement in detective work stems from a desire to aid the unjustly accused and to restore moral balance to his community. This contrasts with Welt’s self-serving demonstration of superiority, as Small engages in gentle discourses highlighting the ethical dimensions of Judaism, often drawing comparisons with Christianity. Thus, while both detectives embody the intellectual rigor at the heart of Kemelman’s stories, their motivations and impacts on their fictional worlds diverge significantly.

Critic Diana Arbin Ben-Merre emphasizes Kemelman's instrumental role in broadening the cultural landscape of detective and mystery fiction in both America and Britain. Prior to the 1960s, Jewish characters in such genres were either absent or tainted by enduring stereotypes and anti-Semitism. The emergence of Rabbi Small as a prominent figure in mystery fiction marked a significant cultural shift. Kemelman's work parallels that of Jewish-American postwar novelists like Saul Bellow, Bernard Malamud, and Philip Roth, who brought Jewish culture into the literary mainstream, demonstrating its richness and appeal. Through the Rabbi Small series, Kemelman not only captivated readers with intricate mysteries but also introduced them to the complexities and nuances of Jewish life and thought.