At a friend’s birthday party in 1885, a 14-year-old Marcel Proust filled out a series of personal questions that became the Proustian Questionnaire. His replies were as telling as they were succinct. “What is your idea of the depths of misery?” he was asked, and reported simply, “To be separated from Mother.” She was likely still on his mind a few questions down, when he answered that the type of heroine he most desired was “a woman of genius who lived the life of an ordinary woman.”

Evelyn Bloch-Dano’s “Madame Proust” (University of Chicago Press, 310 pages, $27.50) is a vivid, if highly impressionistic, account of the life of Jeanne Weil Proust, a woman who outwardly lived the life of a typical Jewish bourgeoise of the Third Republic, but who succeeded in raising France’s unlikeliest literary giant. While Proust’s father wrote off his oldest son as a slacker aesthete, Jeanne was his amanuensis, his moral enforcer and, though she never got her hands on “La Recherche,” his most dogged fact-checker. Even when Proust was a lycéen, she was chiding him for insufficient updates:

Could you not also, my darling, date each of your letters; I’d follow things more easily. Then tell me:

Woke at —
Went to bed at —
Hours of fresh air —
Hours of rest —
Etc.

For me the statistics would be most eloquent and in a few lines you would have successfully fulfilled your duty.

If this sounds like a fin de siècle Mrs. Portnoy, consider also that Jeanne’s concern for her son went far beyond his bedtime. Ms. Bloch-Dano speculates that Jeanne and her husband openly discussed at the dinner table what to do about Marcel’s “dangerous” onanistic habits. We do know, at least, that she forced him to write an astonishingly frank letter to his grandfather in which Marcel asks to borrow 13 francs to repay a debt incurred during a failed visit to a prostitute, arranged by his father to cure him of his “bad tendencies.” When it became clear that her son’s affections ran the other way, Jeanne forbid boys she knew he was attracted to from sleeping over.

And yet for all this, Jeanne Weil was much more than a smothering mother: Her relationship with her son must count as one of the most remarkable collaborations in literary history. Not only did she pass on to Marcel her love of music (Mozart, Gounod) and literature (Madame de Sévigné, George Sand), but she worked closely by his side in the years leading up to his masterpiece. When Proust first heard the call from John Ruskin in 1897, and desperately wanted to spread the good word of “The Bible of Amiens” despite barely knowing English, his fluent mother had translated drafts waiting for him when he woke in the late afternoon.

Ms. Bloch-Dano has conceived of “Madame Proust” in the spirit of earlier impressionistic work on Proust, such as George Painter’s charming 1959 two-volume study of the author, which aims less at interpreting the life in the context of the great work than at lulling the reader into a seamlessly reconstructed narrative. Sometimes the method works against Ms. Bloch-Dano, who occasionally finds herself oddly in competition with the narrative of Proust himself: Both novelize the raw material of the author’s life into the triumphant story of a social butterfly’s metamorphosis into a transcendental artist.

But where “Madame Proust” truly succeeds, and goes further than Painter and Jean-Yves Tadié’s definitive biography (1996), is on the complicated matter of Jeanne and her son’s Jewishness. Jeanne hailed from a family of Alsatian Jews, who had quickly distinguished themselves after Napoleon Bonaparte granted citizenship to Jews in France. (Her great-grandfather was among a handful who received the Legion of Honor for his work as a porcelain manufacturer.) On his mother’s side, Proust was the cousin-in-law of the philosopher Henri Bergson, and a distant cousin of Karl Marx. Like many Parisian Jews, however, the Weil family “wanted to be Jewish but didn’t like being reminded of it,” as the historian Simon Schwarzfuchs has aptly put it. When Jeanne married Dr. Adrien Proust, a Catholic, and an up-and-coming star of French medicine, she didn’t convert, but nor did she protest raising Marcel and his brother, Robert, as Catholics.

Mother and son liked to joke about the awkwardness of certain Jews in society. Ms. Bloch-Dano quotes Jeanne in letters referring to her less assimilated acquaintances as the “the sydicaliste” or the “Semitic element.” Proust himself in “La Recherche” makes the most suave and sophisticated character a Jew (Charles Swann), but also the most obnoxious and socially overeager one (Bloch). “Every aging Jew,” he told one of his cousins, “turns into either a prophet or a boor.” But this slick attitude was no longer tenable after the Dreyfus Affair. The false conviction for espionage of a Jewish soldier, Alfred Dreyfus, had revived anti-Semitism in France and driven an unbreachable rift through the salons and right through the Proust family. Adrien Proust initially sided with the nationalists against Dreyfus, whereas Jeanne, Marcel, and Robert, convinced of his innocence, were among the earliest Dreyfusards.

Jeanne Weil Proust died in 1905, five years before “Swann’s Way” appeared. Proust was devastated by the loss, but also felt liberated to embark on the work he had spent his whole life preparing — and would spend the rest, down to the last hours, writing. Reams of monographs and articles appear every year accounting for new themes and influences on “La Recherche,” but “Madame Proust” tempts us to read the big book in a new way: as the most fulsome possible answer to a mother’s wish to know what occupied her son. For this literary labor, Jeanne trained her boy well. “Though not a Roman, act the Roman’s part,” she intoned to him from her deathbed. Marcel Proust was the farthest thing from a stoic, but he got the job done.

Mr. Meaney is a graduate student in the history department at Columbia University. He last wrote for these pages on the New Criterion.