With the publication of “Lamentations of Youth” (Belknap Press, 284 pages, $39.95) — selections from the notebooks of the philosopher and Kabbalah scholar Gershom Scholem between 1913 and 1920, starting when he was 16 and ending when he was 23 — Belknap Press has added immeasurably to our knowledge of Scholem’s life, a project started with its publication of “Gershom Scholem: A Life in Letters” (2002). Both volumes have been translated and edited by David Skinner.

But there are problems. The notebooks are a much-shortened version of the lengthy two-volume German edition. We don’t know what the German editors have omitted from their prodigious work, and we can only guess — based on Mr. Skinner’s scrupulous foreward — what further omissions he has made. The aim, Mr. Skinner writes, was to concentrate on aspects of Scholem’s personal life, and he thus chose to exclude Scholem’s notations concerning his unpublished essays, his ambivalent relationship to the Zionist youth movement in Germany, and his reflections on the philosophy of mathematics.

Scholem was quite secretive about the diaries, and kept them locked up in his home in Jerusalem — indeed, they were even off-limits to his widow, Fania Freud. En plus Fanya, his second wife, insisted that the more personal and erotic sections of the diary also be edited out. With so much editing out, should we blame Scholem or his editors for what seem to be omissions of entry of what must have been his daily life? Does this excessive editing account for my occasional feeling that I am reading through scrim?

Young Gershom, awkward, arrogant, melancholic, and constantly seeking refuge in a rapidly moving kaleidoscope of ideas, was his parents’ fourth, most rebellious son. (The third, Werner, briefly a follower of Rosa Luxembourg, was murdered by the Nazis in 1940 in Buchenwald.) Arthur Scholem, a tough, successful printer, was a member of neither the German Jewish elite nor the German establishment but, like many German Jews of his generation, deluded himself into believing that there was no difference between himself and German Gentiles — that there was no anti-Semitism in Germany.

Gershom shrewdly observed that despite his father’s pretensions, the Germans with whom he did business did not mix socially with the Scholems, and Gershom fought bitterly with his father over the elder Scholem’s indifference to Jewish tradition and misguided attempt to be an unquestioning German patriot. Gershom flirted with anarchism, then perused his own very individual brand of Zionism, and emigrated in 1923 to Jerusalem, where he became the first Professor of Jewish Mysticism at the Hebrew University of Jerusalem, and a huge force at making that subject — and the study of the Kabbalah — a serious scholarly enterprise.

Nonetheless, Gershom, always self-contradictory, occasionally exhibited some of the jarring prejudices of his time. Despite his avowal that Grete Bauer meant more to him than his best friend Walter Benjamin, he writes: “I’ll take the risk — without being trivial — of uttering again the eternal truth: the spheres of men and women are different. The public sphere is not that of woman. I don’t want to see them in public. I am no defender of women’s rights.”

And yet the going mode of German Jewish intellectuals of the period — in their attitude toward women, among other topics — was considerably more tolerant than that of the bookish Scholem. The Austrian humorist Alexander Roda Roda describes in his autobiography a soirée in his Berlin apartment: “… one encounters a unique society of Arab intellectuals, Zionist leaders, women cabaret dancers … Austrian socialist leaders and demented Hapsburg counts; Stefan Zweig, Heinrich Mann, George Grosz and Joseph Roth, with his companion [her father was a Cuban black jazz artist] — the former mistress of an African tribal leader — and Roth’s two small [adopted] Negro boys, running through the apartment.”

“Lamentations of Youth” provides intriguing access to a young man’s whoosh of ideas in a time when socialism, anarchism, Zionism, modernism, and cubism were revolutionizing the world. Scholem leaps rapidly from this to that, metamorphosing from an uncertain student at Berlin University momentarily thrilled by Martin Buber, to a more confident thinker, gulping down the writings of Tolstoy, Nietzsche, and S.Y. Agnon. He observes of himself that he needed to be “against something,” and his opposition to what he considered outmoded versions of Zionism, Jewish rationalistic reasoning, and old classical Europe led him to resurrect medieval works on Jewish mysticism and the Kabbalah, then almost entirely ignored.

Scholem’s seminal works — among them “Sabbatai Zevi,” “The Mystical Messiah,” “Origins of the Kabbalah,” “Zohar — The Book of Splendor,” and “Kabbalah and Counter-History” — have made him the absolute scholarly authority on the Kabbalah and Jewish mysticism. (His reproach to Hannah Arendt for what he felt was her frivolity in “Eichmann in Jerusalem” is also famous.) As head of the Department of Hebrew and Judaica at the National Library, he was responsible for the amassing and preserving of previously neglected Judaica and, later, as professor at the Hebrew University of Jerusalem, he was a seminal figure in establishing the importance of linguistic theory in recovering the true history of the past.

Scholem’s belief in “essence” — that which cannot be explained — was a central aspect of his approach to scholarship. “There are parts of the Bible that we know only through tradition rather than by reading, as we never read them. Nor is it necessary. You can know the Bible after reading fifty lines from some essential passages.” At the same time as he was meditating on the ineffable qualities of scripture, Scholem was drenching himself in pure mathematics, which brought him into a similar state of ecstasy. His sense that mystical knowledge could be achieved through intellectual rigor became the hallmark of his later work. “In thinking about mathematics, I’ve come up with sharper formulations of the idea that, excepting mysticism, only mathematics can know something in its essence. All knowledge is thus mathematical and deductive.”

While Scholem was in this mathematical swoon, he was also carrying on a personal experiment with a self-denying chastity: lusting for Grete Bauer, courting his first wife Elsa Burckhardt, while, via mathematical numbers theory, discovering the allure of the Kabbalah. Though we have no real way of speculating whether the key women in his life, so important to him both intellectually and physically, were linked to his initial fascination with the Kabbalah, my intuitive hunch is that the discombobulating differences between his physical desires and his desires for purity helped to push him forward toward the unknowable.

That same penetrating curiosity led Scholem to insights on a diverse collection of subjects, but he always circled back to his own particular set of concerns. One of the unexpected delights of these notebooks is Scholem’s long riff on the art of Picasso and Chagall. His meditations on the symbolic content of art and music have hugely influenced writers like Borges, Umberto Eco, and Derrida.

“Picasso’s ‘Woman with the Violin’ seems Jewish,” Scholem wrote. Undoubtedly also on Scholem’s mind was that art and architecture in Picasso’s native Andalucia derived from Muslim and Jewish sources, with their prohibition on figurative art. As critics such as Gerald Brennan (and later Saul Bellow) noted, Spanish literature and culture retained a Jewish cast to it well into the 16th century. Scholem himself wrote on Moses de Leon, who discovered or probably wrote the Zorah, and Girona, a stone’s throw away from Barcelona, was the most important early center of the Kabbalah. “Jewish art resists the creation of new forms and seeks mathematical-metaphysical knowledge. The Jewish image of a man must be cubist.”

Ms. Solomon, an essayist and novelist, is cultural correspondent of El Pais.