He was sent to love with his maternal grandmother and at the age of thirteen Euler entered the University of Basel. He received a Master of Philosophy having written a dissertation comparing the philosophies of Descartes and Isaac Newton. He began receiving lesson from Johann Bernoulli on Saturday afternoons. Bernoulli quickly discovered Euler's incredible talent for mathematics.
Euler had been studying Hebrew, Greek, and theology for his father hoped he would become a pastor. Euler's father wanted him to become a minister so he nearly missed pursuing the field of mathematics. He pleased with his father to allow him to pursue that field at which he was best suited. His father relinquished his his desire to his sons expectations. It was Paul Euler's friend Bernoulli who convinced him to permit Leonhard to study mathematics.
While attempting to obtain a position at the University of Basel in 1726, Euler completed his dissertation on the propagation of sound titled De Sono. Although he was unsuccessful in his attempt to obtain a position at the University; he entered the Paris Academy Prize Problem competition.
The problem to solve was to find the best way to place masts on a ship.
Pierre Bouguer, eventually known as “the father of naval architecture” solved the problem with the winning answer. Leonhard Euler won second place but subsequently won the coveted annual price twelve times in his lifetime.
Euler made major contributions advancing arithmetic, geometry, trigonometry, and calculus. He was a pioneer Swiss mathematician and physicist making several discoveries in the fields of infinitesimal calculus and graph theory. Leonhard Euler was the mathematician who introduced much of contemporary mathematical terminology and notation particularly for mathematical analysis.
The Euler constant, Euler numbers, Eulerian integrals as well as other mathematical forms and symbols are named for him. He was famous for his work in mechanics, fluid dynamics, optics, and astronomy.
Leonhard Euler is considered to be the preeminent mathematician of the 18th Century and is among the greatest mathematicians of all ages.
This statement which is attributed to Pierre-Simon Laplace expresses Euler's influence on mathematics:
"Read Euler, read Euler, he is our teacher in all things," also translated as "Read Euler, read Euler, he is the master of us all."
Catherine I of Russia invited Euler to teach at the Academy of Sciences in St. Petersburg. Unfortunately, she died before Euler received the appointment. His financial circumstances were such that he considered a position in the Russian navy. Fortunately, he did receive the teaching position at the Academy and didn't go to sea.
He eventually married and had children which would sit upon his lap while he produced work of high-caliber which amazed his friends. He was invited to Prussia by Frederick the Great after he became a renowned mathematician. Voltaire and Frederick hated Christianity and mocked Euler for his 'simple' beliefs.
Euler published “Letters to a German Princess” which was a book of science and faith written for his pupil Frederick's niece although Frederick was uncouth and mean.
Much of what we known of Leonhard Euler's Protestant Christian beliefs can be deduced from “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 of Euler clearly reveal that he was a devout Protestant Christian who believed the Bible to be inspired; the Rettung is primarily a lucid argument defending the divine inspiration of scripture.
“Letters to a German Princess” was eventually translated into seven languages and widely read throughout all of Europe. Euler brought academic luster to the Berlin Academy. Unfortunately, Frederick turned against Euler so the eminent mathematician returned to Russia.
Euler produced an earlier work titled: “Defense of the Divnie Revelation against the Objections of the Freethinkers.These works clearly indicate the Euler was a devout Protestant Christian believing in the inerrant Scriptures.
David Brewster was a nineteenth-century physicist and biographer of Euler. He notes that Euler's fame and disruptions throughout his life:
“never induced him to abandon the religious duties to which he had been educated. As long as he preserved his sight, he assembled the whole of his family every evening, and read a chapter of the Bible, which he accompanied with an exhortation.”
It is interesting to examine how Euler was viewed in Frederick's court in the light of Euler's strong Protestant Christian belief.
Euler's student. Nicholas von Fuss, observed that his instructor's
“piety was rational and sincere. His devotion was fervent. He was fully persuaded of the truth of Christianity. He felt its importance to the dignity and happiness of human nature, and looked on its detractors, and opposers, as the most pernicious enemies of man.”
Euler wrote apologetics arguing forcefully against prominent atheists of his age.
A famous anecdote which was inspired by Leonhard's arguments which occurred with secular philosophers concerning Christinity. The contest occured after Euler's return to academy in St. Petersburg.
Denis Diderot, the French philosopher, was visiting Russia at the invitation of Catherine the Great. The Empress became alarmed by the philosopher's attempt to influence the members of her court through intellectual argument supporting atheism. Leonhard Euler was asked to confront the French freethinker. The French philosopher was informed that a learned mathematician had proof of the existence of God. Diderot agreed to examine the proof as it was presented by the mathematician in the court.
Euler appeared in the court of Catherine the Great and approached Diderot. In a tone of perfect conviction Euler announced to Diderot:
God exists – reply!”
Pearls of laughter erupted from the court of Catherine the Great. Diderot, to whom all mathematics was gibberish – so says the story – was dumbstruck.
Consequently, he was embarrassed and asked to leave Russia, a request which was graciously granted by the Empress of Russia.
The anecdote is apocryphal given that Diderot was a capable mathematician who published several mathematical treatises which he had written.
Although his house burned; his papers were saved. It appears that disaster began to stalk him for his wife died in 1773 after 40 years of marriage. Three years after the death of his beloved wife Katharina; he married her half sister, Salome Abigail Gsell (1723-1794). His marriage to Salome lasted until his death.
While solving a problem in three days which would take most mathematicians a month to solve; he lost his sight. Eventually, a cataract formed in his good eye. A few weeks after the cataract was discovered in 1766; it rendered him nearly totally blind.
Surgery restored sight in both eyes but an infection causing excruciating pain took his sight in both eyes. He declared that only his faith in God enabled him to bear the pain.
Among the greatest achievements in science was the fact that he solved some of the most difficult mathematical problems on the blackboard of his mind while not being distracted by the activities surrounding him. He would dictate the solutions to his friends who would document the achievement.