The Jewish Polymath Who Studied With Galileo—and Collected 7,000 Books

Picture a Jew in the 17th century, sitting in a small room with a telescope, a Torah scroll, an open Gemara, math texts, and alongside them books of Kabbalah. This is Yosef Shlomo Delmedigo, the Yashar of Candia (1591–1655) — a rabbi, physician, mathematician, astronomer, and kabbalist who was part of the Scientific Revolution. He studied with Galileo, roamed between Crete, Cairo, Constantinople, and Prague, and wrote books that connected science and Kabbalah. Delmedigo saw in nature the “wonders of creation” — a divine work that should be explored with an open mind and heart. His story is one of courage, curiosity, and bridging worlds, which influenced Judaism and science.

Yosef Shlomo Delmedigo was born on June 16, 1591, in Candia (today’s Heraklion), Crete, to a family of scholars and physicians. His grandfather, Elijah Delmedigo, was a famed philosopher, and the family, originally from Germany, had settled in Crete and Italy. From a young age he stood out as a prodigy. He excelled in sacred study, but his boundless curiosity led him to other fields too—languages like Greek, Italian, and Spanish, as well as astronomy, mathematics, and more. At 15, in 1606, he moved to Padua, Italy, and studied at the city’s university, the “University of Padua,” a leading institution of the era. There he studied medicine, mathematics, astronomy, and philosophy, and was deeply influenced by Galileo Galilei, whom he called “my teacher” in his book Elim. He completed his studies in 1613 with a medical degree and began amassing a vast library of about 7,000 books—an astonishing number for his time (and even for ours).

After finishing his studies, Delmedigo didn’t stay put. He returned to Candia, married, and had a daughter, but his wife passed away, and his passion for science—and for weaving it together with the Torah—stirred in him a need to wander. In 1616 he set out, reaching Alexandria and Cairo, where he debated local mathematicians and impressed them with his wide-ranging knowledge. In Constantinople he observed a comet in 1619, demonstrating his astronomical chops. Between 1620 and 1624 he served as personal physician to Prince Janusz Radziwiłł in Lithuania, all while continuing to research and write. He also lived in Hamburg, Glückstadt, and Amsterdam, where he served as a rabbi and preacher, and he eventually settled in Prague. His book Elim included answers to questions from a Karaite sage on astronomy, mathematics, and alchemy, showcasing his broad expertise. He was regarded as a posek of halacha, and even the commentator on the Shulchan Aruch, the Shach, cites him in the laws of meat and milk.

The most fascinating part of his life is how he managed to weave together so many fields—even ones that seem to contradict each other—like science and Kabbalah. Delmedigo didn’t stop at science. At first he was skeptical of Kabbalah and even mocked it as a teenager. But in Constantinople, after meeting Rabbi Yaakov ben Nachmias, he began to see parallels with Plato’s philosophy. In his book Matzref LaChokhmah, he defended Kabbalah against the criticism of his grandfather, Elijah Delmedigo, who doubted the authenticity of the Zohar, and he went on at length explaining how Kabbalah fits with science and philosophy. Delmedigo saw in nature and the heavens the “wonders of creation” — a way to understand Hashem through science and spirituality.

Yosef Shlomo Delmedigo died on October 16, 1655, in Prague and was buried in the local cemetery. He left behind roughly 30 to 60 works, most in manuscript, covering subjects such as medicine, astronomy, mathematics, and Kabbalah. Despite controversies—such as the rejection of some of his writings by the Ramaz—he influenced later Jewish scholars and showed how science and faith can be brought together. His enormous library of about 7,000 volumes testified to his passion for knowledge. Delmedigo was a trailblazer who saw the “wonders of creation” as an invitation to explore the world, and his legacy continues to resonate.