Euler's Formula to Explain God's Existence (18th century)

Leonhard Euler (April 15,1707 – September 18, 1783) was a pioneering Swiss mathematician and physicist who made important discoveries in fields as diverse as infinitesimal calculus and graph theory. Euler also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion of a mathematical function, and he is renowned for his work in mechanics, fluid dynamics, optics, and astronomy. He spent most of his adult life in St. Petersburg, Russia and in Berlin, Prussia.

Much of what is known of Euler’s religious beliefs can be deduced from his Letters to a German Princess and an earlier work, Rettung der Göttlichen Offenbahrung Gegen die Einwürfe der Freygeister (Defense of the Divine Revelation against the Objections of the Freethinkers). These works show that Euler was a devout Christian who believed the Bible to be inspired; the Rettung was primarily an argument for the divine inspiration of scripture.

There is a famous legend inspired by Euler’s arguments with secular philosophers over religion, which is set during Euler’s second stint at the St. Petersburg academy. The French philosopher Denis Diderot was visiting Russia on Catherine the Great’s invitation. However, the Empress was alarmed that the philosopher’s arguments for atheism were influencing members of her court, so Euler was asked to confront the Frenchman. Diderot was informed that a learned mathematician had produced a proof of the existence of God; he agreed to view the proof as it was presented in court. Euler appeared, advanced toward Diderot, and in a tone of perfect conviction announced the following non-sequitur: “Sir, frac{a+b^n}{n}=x, hence God exists—reply!” Diderot, to whom (says the story) all was gibberish, stood dumbstruck as peals of laughter erupted from the court. Embarrassed, he asked to leave Russia, a request that was graciously granted by the Empress. However amusing the anecdote may be, it is apocryphal, given that Diderot himself did research in .

Euler was featured on the sixth series of the Swiss 10-franc banknote and on numerous Swiss, German, and Russian postage stamps. The 2002 asteroid Euler was named in his honor. He is also commemorated by the Lutheran Church on their Calendar of Saints on May 24, since he was a devout Christian (and believer in biblical inerrancy) who wrote apologetics and argued forcefully against the prominent atheists of his time. On April 15, 2013, Euler’s 306th birthday was celebrated with a Google Doodle.