Leonhard Euler (April 15, 1707 – September 7, 1783) was born in Basel to Paul Euler and Marguerite Brucker. Maguerite was the daughter of a pastor and Paul was a pastor himself! With such parents, Euler was expected to be a pastor too. He received this formal education in Basel. He was studying theology, Greek and Hebrew, urged by his father so as to be able to be a pastor. He received a master of philosophy degree in 1723. Little does the young genius know of his budding talent in mathematics!

Discovery of his talent

It was, however, Johann Bernoulli who discovered his talent. Euler, in the University of Basel, met Johann, a friend of Paul Euler. Friendly Euler befriended Johann, who had a bad temper, to the extent that Johann was willing to provide him with private lessons. Johann, a one of the most foremost mathematician in Europe, discovered young Euler’s talent in the mathematical aspect. He convinced Euler’s father to allow Euler to take the path of a great mathematician he was to be. He also befriended Daniel and Nicolas Benoulli, sons of Johann Benoulli, who would soon play an important role in his life.

Paris Academy Prize Problem

Euler first entered the Paris Academy Prize problem in 1727, at a mere age of 20. Already, despite his age and inexperience, he managed to win the second place. However, this was just the tip of an iceberg, for Euler managed to cling onto the coveted championship for a stunning 12 times in his career

Imperial Russian Academy of Sciences

He also befriended Daniel and Nicolas Benoulli, sons of Johann Benoulli, who would soon play an important role in his life. Both of them worked in the Imperial Russian Academy of Science in St Petersburg. It was a newly opened centre of science. As Russia had few scientist of its own many foreigners were invited to work there. Sadly, in 1726, Nicolas died of appendicitis and Daniel assumed his brother’s post in the mathematics/physics division. His vacant position in the physiology division was filled up by Euler. This brought upon Euler, a great opportunity to display his talents in mathematics

Position in Mathematics Division

Euler swiftly rose through the ranks after the death of Peter II. He was eventually made professor of physics in 1731. Two years later, Daniel left St Petersburg, angry with the censorship and hostility he faced. He left for Basel. This brought upon Euler a brilliant opportunity to succeed him as the head of mathematics division. He eagerly accepted the post.

Marriage and Childrens

On January 7, 1734 he married Katharina Gsell, daughter of a painter from the Academy Gymnasium. They lived happily in a house by Neva River. During that period, they had 13 children, of whom, only 5 survived their childhood due to poor health care at that period of time.

Berlin Academy

The reknowned Frederick the Great of Prussia offered him a post at the Berlin Academy, in which he accepted with much gratitude. Leaving St. Petersburg in 1741, he lived 25 years in Berlin, where he wrote over 380 articles. It was also in Berlin where he published two works that brought him to fame – Introductio in analysin infinitorum and the Institutiones calculi differentialis.

Letters of Euler

Euler was requested to tutor the Princess of Anhalt-Dessau, his benefactor, Frederick’s niece. He wrote over 200 letter to her, touching on various topic pertaining to physics and mathematics, as well as offering valuable insight on Euler’s personality and religious beliefs. It was compiled into a book, published all over Europe and United States – Letters of Euler on different Subjects in Natural Philosophy Addressed to a German Princess. This book was so widely read to the extent that it was more widely read than any of his other mathematical works. The popularity of the book was attributed to Euler’s ability to communicate complicated scientific theories to lay men. This was indeed a rare ability for a scientist.

Blindness

In 1735, he had a severe fever, and almost lost his life. He wrote in his autobiography that his eyesight started having problems in 1738, and blamed it on eyestrain caused by his cartographic work. However, some historians argue that Euler’s eyesight problems started earlier, and that the fever was a symptom of the eyestrain. Also, a portrait of Euler in 1753 suggests that Euler’s left eye was still good, while his right eye, although poor, was not completely blind yet. During his time in Germany, Euler’s eyesight worsened, so much so that Frederick the great called him “Cyclops”. Upon his return to Russia, Euler became almost entirely blind after an illness. A cataract operation after the fire restored his eyesight for a few days, but Euler failed to take proper care of himself, and became totally blind. However, this did not result in him being unable to work, as he had a photographic memory, and the ability to concentrate very well. Some historians have said that Euler would work with “a baby in his lap and older children running at his feet”. Also, there was once a story in which two students were arguing over a calculation, in which they disagreed at the 50th decimal place. Euler settled this argument by recomputing the sum in his head and the answer proved to be correct. Amazingly, Euler produced about half of his total works in total blindness.

This was not possible without the help. For example, Euler credits Albrecht, Krafft and Lexell for their help with his work on the motion of the moon. He also introduced the symbol i to represent the square root of -1 in 1777, one of the many notations he introduced over his life.

Fire in 1771, death of his wife in 1773

After living in Berlin for many years, Euler accepted an invitation from the St Petersburg academy to return to them and to spend the rest of his life in Russia, however, his second stay in Russia was filled with tragedies, the fire in 1771 cost him his home and nearly his life (he only managed to save himself and his mathematical manuscripts), and in 1773, his wife of 40 years, Katharina Gsell, died. However, Euler remarried 3 years later.

Death

Euler passed away in St Petersburg after suffering from a brain hemorrhage and was buried in Alexander Nevsky Monastery (Which holds the tombs of many famous people, including Tchaikovsky). On the day that he died, he showed no signs of weakness, and only until after dinner, when his Grandson came to play with him, did “the pipe that he was smoking [slip] from his hand and he ceased to calculate and to live”. However, what is most interesting about the entry written in the eulogy was that Euler was actually in full control of himself, and one of the symptoms of a hemorrhage would be a headache. If it was serious enough to kill him, there would be obvious signs. However, the eulogy does not mention any at all. However, from his biography, it states that Euler suffered the hemorrhage at about 5pm, only managing to utter “I am dying” before losing consciousness and dying at around 11pm.