September 18 is the anniversary of the death of a mathematical and scientific genius, an outspoken Christian who defended the faith during the Enlightenment, when Christianity was under attack by much of the intellectual elite in Europe. 

Leonhard Euler was the son of Paul Euler, a Reformed Church pastor in Basel, Switzerland. He began study at the University of Basel at 13 and completed a master’s degree in philosophy at 16. Though he originally intended to become a pastor, once his mathematical genius became evident, he changed the focus of his studies.  

In 1726, Euler completed a dissertation on the propagation of sound. The following year, he took second place in a prestigious Paris Academy prize competition, a competition Euler would win 12 times. 

When he didn’t get a professorship at the University of Basel, Euler went to the St. Petersburg Academy of Sciences in Russia. Initially, he served in the medical department, working as a medic to the Russian navy. He was quickly promoted and, in 1731, was named a professor of physics. In 1733, Euler was named head of the mathematics department. 

In 1741, partly due to a growing xenophobia in Russia, Euler accepted a position at the Berlin Academy. In the 25 years he spent there, he published over 380 articles, along with important books on mathematical functions and differential calculus. Frederick the Great asked Euler to mentor his niece, the Princess of Anhalt-Dessau. Euler wrote over 230 letters on science, philosophy, and religion to the princess, which were later compiled into a bestselling book.  

Unfortunately, Euler’s faith and conservative, hardworking lifestyle did not sit well with the atmosphere of Frederick’s court. By 1766, the situation in Russia had stabilized under Catherine the Great, so Euler returned to the St. Petersburg Academy of Sciences. 

That same year, Euler was diagnosed with a cataract in his left eye. Within a few weeks of its diagnosis, he was almost completely blind. Though for most people, this would have been a career-ending affliction, Euler became even more productive than before.  

It helped that he had a photographic memory. For example, he could recite Virgil’s Aeneid verbatim and could even tell the first and last lines from any page of the edition he had learned. Also, his ability to concentrate was legendary. According to one story, two of his students working on a series of highly complicated mathematical problems could not agree on the fifteenth decimal point. Euler settled the argument by doing the calculation in his head.  

In addition to his remarkable abilities, Euler had a prodigious capacity for hard work. In 1775, he produced roughly one mathematical treatise each week for the entire year. By the end of his life, Euler had produced 886 academic papers and books that filled roughly 90 volumes, making him one of the most productive mathematicians in history. In fact, the last phase of his life was so prolific that the St. Petersburg Academy did not complete publication of his papers until 30 years after his death. 

Amidst this prodigious output, Euler never left behind the theological commitments and interests of his youth. Like many Christian scholars of the time, he wrote against the anti-religious thinkers of his day, particularly defending biblical inspiration. He combined his mathematical and scientific interests with theology and used his skills in the defense of the faith, challenging the claims to knowledge of other philosophies as “heathen and atheistic.” 

Overall, Euler’s mathematical work was an expression of his deep faith as a Christian who recognized Jesus as the logos, the sum of all knowledge and truth. His work was an expression of a worldview that recognized that every area of life is worthy of exploration as an act of worship and service to God. 

This Breakpoint was co-authored by Dr. Glenn Sunshine. For more resources to live like a Christian in this cultural moment, go to breakpoint.org.