When University of Haifa’s Prof. J. H. (Yossi) Chajes arrived in Cambridge this winter to deliver Harvard University’s Houghton Medieval Studies Lecture in Early Book History, he brought with him decades of groundbreaking scholarship—work that has reshaped how we understand the intertwined histories of Kabbalah (Jewish mysticism), magic, and science.
Harvard’s Houghton Library is one of the world’s great research libraries. Its prestigious annual lecture invites a scholar not only to present a public address, but to spend a week leading hands-on workshops with rare books and manuscripts. In all the years of the series, it had never focused on Jewish culture or Jewish manuscripts. This year, for the first time, it did—because of Chajes.
For Chajes, the invitation is meaningful not simply because it comes from Harvard, but because it signals that his work resonates far beyond Jewish studies. “It’s especially nice,” he reflects, “when I’m invited somewhere and see that my work has reached scholars and disciplines that many people in Jewish studies don’t typically reach.”
Last year at this time, he delivered a comparable lecture at Yale University. Together, the Harvard and Yale presentations testify to the international visibility of his research.
At University of Haifa, where he is the Sir Isaac Wolfson Professor of Jewish Thought in the Department of Jewish History, Chajes occupies a rare intellectual crossroads. His scholarship centers on the intersection of Kabbalah, magic, and science in Jewish cultural history
At first glance, those may seem like separate—and even incompatible—domains. In Chajes’ work, they form a single, dynamic field of inquiry.
His path toward that field began early. As a young student, he found himself captivated by Kabbalah and mysticism, wrestling with whether to pursue them as a practitioner or as a historian. Ultimately, he chose an academic path, earning his Ph.D. at Yale in 1999. But he never lost sight of the existential questions that first drew him in: How did we move from a world alive with spirits, angels, and cosmic forces to a modern, “disenchanted” one? How did magic become superstition, and science the sole arbiter of truth?
According to Chajes, the transformation occurred in the 16th and 17th centuries, a period of profound cultural transition. During this era, disciplines we now consider distinct—alchemy and chemistry, astrology and astronomy, magic and science—began to separate. What had once been taught in universities under the broad umbrella of “science” was gradually rejected, misunderstood, or marginalized.
In recovering that earlier intellectual world, Chajes challenges modern assumptions about what Judaism “always” looked like and how Jews have understood reality. This commitment to Kabbalah as lived culture—rather than abstract philosophy—shaped his book, Between Worlds: Dybbuks, Exorcists, and Early Modern Judaism (2003). Exploring spirit possession and exorcism, the book opened a new window onto women mystics, healing practices, and popular prophecy. The Wall Street Journal later listed it among the top five books ever written on spirit possession—a remarkable distinction for a work of Jewish cultural history. He also speaks and serves as a guest cantor in Jewish communities around the world, to all denominations.
Yet perhaps his most ambitious project emerged almost by accident.
About 15 years ago, Chajes encountered a largely ignored corpus of Jewish artifacts known as ilanot—intricate Kabbalistic diagrams and “trees” that combine text and image. Though their imagery often appears on book covers about Kabbalah, the genre itself had never been systematically studied. When a private collector discovered that scholars could not even tell him what these manuscripts were, Chajes realized he had stumbled onto an uncharted field.
The result was the Ilanot Project, which he has directed for over a decade. An unprecedented effort to document and analyze the history of Kabbalistic diagrams, the project has garnered five consecutive Israel Science Foundation personal research grants, multiple seminar grants, and the 2014 Friedenberg Prize for the outstanding ISF-funded humanities project. With support from the German Ministry of Science and Culture and the Volkswagen Foundation, Chajes partnered with the University of Göttingen to create Maps of God, a digital humanities platform for critical editions of ilanot.
In these remarkable manuscripts—produced in Italy, North Africa, Yemen, Kurdistan, Holland, Iraq, and Israel—Chajes saw the perfect convergence of his lifelong interests. They integrate Kabbalah with apotropaic magic (protective practices against evil forces) and borrow visual techniques from medieval natural philosophy and astronomy. In other words, they are artifacts of a time when mapping the divine cosmos drew on the same diagrammatic language used to chart the stars.
His magisterial volume The Kabbalistic Tree (2022) presents 600 years of this genre in a stunningly illustrated history. Featuring 250 color plates and fold-out pages, it has been praised as a “monumental achievement” and was awarded the 2023 Jordan Schnitzer Book Prize in Philosophy and Jewish Thought; it was also a finalist for the 2024 National Jewish Book Award. The book reverses the traditional relationship between text and image: The images are central, and the text explains them.
If Harvard’s invitation highlights Chajes’ impact beyond Jewish studies, his teaching at University of Haifa underscores his influence at home. In Haifa’s remarkably diverse student body, he exposes students to the pluralism of Jewish history, challenging simplistic notions that contemporary Orthodoxy is a frozen relic of the past. By revealing the diversity and dynamism of earlier Jewish worlds, he equips a new generation to think more critically—and more imaginatively—about tradition and modernity.
At a moment when public discourse often flattens both religion and science into caricatures, Chajes’ work reminds us that Jewish history contains rich, complex conversations about knowledge, power, healing, and the unseen. From dybbuks to diagrams, from manuscripts to digital platforms, Chajes continues to illuminate the vibrant intersections of Kabbalah, magic, and science—placing University of Haifa at the forefront of a field he created.
