Gratitude, scientists tell us, is one of the healthiest of emotions. Jewish liturgy is replete with prayers of thankfulness; the reason why many observant Jews attend morning minyan, they say, is to start each day with an “attitude of gratitude.” The Torah suggests that God created humanity, in part, because He needed applause for his sublime authorship. And not just people — the Rabbis believed that every living thing acclaimed God with the song of its own species; these lyrics are contained in the ancient text, “Perek Shirah” (“Chapter of Song”).

Because I’m writing the Acknowledgments to my book on the Jewish deli, I’m thinking a lot about writers’ thank-yous. There is something deeply Jewish about this custom, in which an author concedes that, however much it may seem like a solo project, the work was, in a profound sense, a communal effort. The writer shows that he or she relied upon many others for help, advice, feedback, comfort, encouragement and, in many cases, meals or a place to sleep.

Acknowledgments can be quite moving. Steven Zipperstein, a professor of Jewish history at Stanford, told me that Acknowledgments “educate the reader how, where and why you come to the table.” Rather than a mere courtesy, he reflected, they “provide a human benchmark, a lens into your own soul — the only transparently personal moment that a scholar takes in his or her entire book.”

When modern-day scholars compose Acknowledgments, they walk in the footsteps of medieval Jewish sages who named their books after their father or teacher (often the same person). For Eliezer Diamond, who teaches Talmud at the Jewish Theological Seminary, an “especially poignant” tribute was paid by the 17th-century Moravian rabbi, R. Yair Bacharach, who entitled one of his books “Chavas Yair,” a quote from the Book of Numbers that refers to the villages conquered by Yair. But the title also refers to his erudite grandmother, Eva (Chava) Bacharach, whose own Talmudic commentaries were not preserved.

Even as Acknowledgments have mushroomed in recent years —some now take up multiple pages — authors fret about leaving someone out. As the celebrated Harvard professor Stanley Cavell has written, Acknowledgments stake an implicit claim to a comprehensiveness that is, in reality, impossible. Novelist Andrew Foster Altschul learned this the hard way; he omitted his wife (whom he, in fairness, had just met) from the Acknowledgments to his first book; he made up for it by dedicating his second one to her.

Writers are a notoriously insecure lot, as Paul Zakrzewski, editor of “Lost Tribe: Jewish Fiction From the Edge,” reminded me. The envy, jealousy and sense of inferiority that writers have toward their mentors can make them ambivalent about giving them a shout-out. Little wonder that in the Acknowledgments to her comedic memoir, “The Bedwetter,” Sarah Silverman manages both to praise and to curse her editor, David Hirshey, in the same breath.

Acknowledgments can sometimes be a way of impressing the reader with how well-connected the author is, by listing a veritable who’s who of those in the publishing industry who purportedly helped the author with his or her magnum opus. In an effort to remedy this, blogger Emily Gould (former editor of has issued her own rules for Acknowledgments, which urge budding writers to refrain from name-dropping, as well as from thanking deceased people or deities.

Some have called for Acknowledgments to be abolished altogether. In a 2012 New Yorker article, “Against Acknowledgments,” Sam Sacks noted that the list of thank-yous in contemporary novels often functions as an extension of the public relations campaign for the book; he called them “garrulously narcissistic and strewn with clichés.”

But when handled with good grace and genuine gratitude, Acknowledgments serve an important purpose of showing others how much they have contributed to the often lonely and tortuous process of writing a book. I will close with my favorite Acknowledgment by a Jewish writer, J.D. Salinger’s dedication to “Franny and Zooey,” his stories about the Glass family. Salinger told his close friend and publisher, William Shawn, that he was proffering the book “as nearly as possible in the spirit of Matthew Salinger, age one, urging a luncheon companion to accept a cool lima bean.”

Could anything be more humble and self-effacing than that?

Ted Merwin, who writes about theater for the paper, teaches at Dickinson College (Carlisle, Pa). His book, “Pastrami on Rye: A History of the New York Jewish Deli,” will be published next year by NYU Press.