John Heilbron

This year is a significant one for the history of science. It marks the 400th anniversary of the publication of a groundbreaking book by Galileo on the scientific method. It is 480 years after the publication of Copernicus’s book on heliocentrism. But 2023 is also a year of mourning. Owen Gingerich, a Harvard astronomer and leading Copernicus historian, died in May . And a few weeks ago, on 5 November 2023, John Heilbron, historian of physicists including Galileo and Max Planck, passed away in Padua, Italy—not far from where Galileo made his first astronomical observations.

John was a great example of what it means to be healthily obsessed with historical research. As he told me, when Oxford University Press asked him to write a book on Galileo, he accepted the invitation only after making sure that he could find something new to say. He read all the massive volumes of Galileo’s letters—and reread them multiple times afterward—and found a novelty. His book placed Galileo firmly within the literary context of Renaissance Florence , by showing that the young Galileo not only wrote poems but also calculated the depth of Dante’s Inferno. Heilbron’s Galileo is still a standard biography, and various historians have described it to me as “the way to do it.”

As a young historian of science, I owe much to John’s work. His book The Sun in the Church: Cathedrals as Solar Observatories taught me, and many readers, the richness of the history of science. Rather than focusing on ideas alone, John followed the breadth advocated by his adviser and mentor, Thomas Kuhn, and argued that cathedrals were key sites of scientific production when used as large instruments for astronomical measurements. The tourist attraction of watching a sun ray crossing meridian lines in Italian churches like the Duomo of Florence owes much to John’s book.

Above all, this book was one of the reasons why, after completing an MSc in physics, I decided to study history. This book challenged many assumptions I had about science. For instance, John boldly claimed that the Catholic Church was the main institution behind early modern astronomical research, despite the more famous Galileo condemnation. Yet, in addition to historical context, he never shunned away from including mathematics to understand what astronomers really did. His book Geometry Civilized, for instance, partly resulted from distractions from his administrative tenure as vice chancellor, “when a geometrical problem seized my mind,” he wrote.

For these reasons, I could not hide my excitement when William Shea, another outstanding Galileo scholar, told me that John lived close to Oxford, where I was visiting in April 2022 for a one-month fellowship. I had just completed my PhD in the history of science, and I was looking forward to meeting him in person. John kindly invited me to his lovely house in Shilton, a one-hour drive from Oxford. At lunch, joined by his beloved wife Alison, I spoke of other historians of science I had met recently, and, one by one, he smilingly would say they had all been sitting in that same chair where I was. Naively, I also asked whether he had ever been to the Max Planck Institute for the History of Science in Berlin (where I was a postdoc at the time). He humbly said he had given the institute’s opening lecture in 1995. John was also a prolific writer on the history of modern physics, having written books about Planck and Niels Bohr—a testament to his mastery of Danish and German, alongside Latin, Italian, and other languages.

My short trip to Shilton taught me much about research life. I saw how John loved his personal life and how he integrated it with his work. When he told me that his wife was the main audience for his ideas, I understood why she features in almost all of his book’s acknowledgments. John did not own a mobile phone and had a strict schedule to read emails, both of which speak to his incredible productivity. His office, carefully placed in a modern, classically looking attic, seemed a remarkable place to perform what authors have called Deep Work . It had small windows so John would not be tempted to stop working when the sun shone. It’s not that he did not want to spend time outside—rather, he liked it too much. His beautiful flower garden had been the ideal site for the intimate launch of one of his books, where his guests performed some of Galileo’s observations at night. After lunch, I accompanied him on his daily hourlong walk through the countryside. Then, he told me stories about working with Kuhn, including writing the footnotes for The Structure of Scientific Revolutions.

I had the pleasure of hosting John and Alison at my apartment in Florence for dinner about a year ago. He was in town to give a talk at the Harvard University Center for Italian Renaissance Studies, where I was a fellow at the time. He kindly showed interest not only in my research and early career but also in my 2-year-old daughter, who was running around. When he left, I thought about how John was still incredibly sharp and in shape for his 88 years. (In fact, he has a book coming out on quantum entanglement .) Sadly, that would be the last time I would see him.

John was Professor Emeritus of History of Science and former Vice Chancellor of the University of California, Berkeley. After completing a master’s in physics (1958) and a PhD in history (1964) from the same university, he rose to become a prolific and influential author in the history of science. He won the highest awards in the discipline, such as the Pfizer Award for best book, The Sun in the Church, and the Sarton Medal for his distinctive career. He was also a member of the Royal Swedish Academy of Sciences, which awards Nobel Prizes to scientists every year.

John told me that in his last phone call with Kuhn, his adviser told him to “keep the faith.” It was a reaction against the relativistic ideology that assailed historians of science at the time which, against Kuhn’s wishes , had been provoked by The Structure of Scientific Revolutions. John certainly kept that faith. May he rest in peace.

Nuno Castel-Branco is a historian of early modern culture and science at All Souls College, University of Oxford, UK.

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