Stepping with Science to Sainthood: Nicolaus Steno’s Conversion and His Unity of Life

Nuno Castel-Branco

The Harvard University Center for Italian Renaissance Studies

In 1667, at the peak of his scientific career, the Danish anatomist Nicolaus Steno (1638-1686)
converted to Catholicism. Since then, much has been written about it. His Protestant friends and
modern historians alike found this conversion perplexing. On the other hand, his Florentine
friends and Catholic apologetics rejoiced and used Steno’s conversion as an argumentative tool.
Yet, most accounts fail to contextualize Steno’s conversion in light of his research interests in
anatomy and, later on, in geology. Did Steno convert only to please the Medici family, his new
patrons? Did he experience a religious experience that suddenly made him want to convert? Or
does his conversion, instead, follow gradually from his pursuit of truth in science? In this lecture,
I explain that Steno’s conversion happened due to a particular moment in his scientific career in
which he was obsessed with finding rigorous scientific knowledge about the world. This search
for certainty, in combination with new friendships, made him leap into the Catholic Church.