**Leonard Euler, 1707 – 1783, **

**Mathematician, Physicist.**

Euler was born in Swizerland but spent most of his life in St Petersburg and Berlin.

His father was a pastor in the Reformed church, and his mother was from a scholarly family.

He married, had a family of 13 children, 3 boys and 2 girls survived, and they all live together with his widowed mother.

*Young Leonard Euler*

Before enrolling at the University of Basel Euler was tutored by a young theologian, who also had an interest in mathematics.

At university, Euler was taught by Johann Bernoulli, an extraordinarily gifted mathematician, who would have seen the potential in Euler, and gave him extra tutoring and privileges.

Nevertheless, Euler was expected to join the church and become a pastor, but with Bernoulli's support and recommendation, Euler was permitted to transfer from the church and become a mathematician.

Euler made major original contributions to most areas of mathematics and physics, and over his lifetime he wrote 866 scientific papers for publication. The original ideas must have been bubbling up in his brain continually.

Laplace and Gauss, both original contributors to mathematics, assessed Euler to be the greatest.

Perhaps his best-known work is the equation

When those 2 non-terminating, irrational numbers e and π, and the square root of a negative number, are combined together they give a simple digit. It's out of this world, unimaginable.

In perhaps a lighter moment, Euler introduced notation that has become standard notation today.

e, is Euler's number, which is the base for natural logarithms.

i, is for √-1,

Σ, for the sum of a series,

π, is the circular ratio, and

f(x), is the usual notation for a function of x.

In 1726 Euler was appointed to the mathematics department at St Petersburg University, then Professor of Physics 1731 and Head of Mathematics in 1735, at the ripe old age of 28.

Six years later he moved back to the Berlin Academy, because of the restrictions in St Petersburg and the harshness of the weather.

Besides his duties at the university, he tutored a German princess, and over a period of time sent her more than 200 letters, on mathematics and physics topics. Those letters have been preserved and are held in a single volume.

**Leonard Euler **

Euler did not seem to relate well with the German chancellor, consequently, when Euler was suggested as the president of the Berlin Academy, the chancellor decided Euler was not well grounded in matters outside mathematics and physics. That could have been an unpleasant setback for Euler, but the chancellor had the last word.

A short time later, during the Seven Years' War, when Euler's property around his home was destroyed by Russian troops, the army General stepped in and paid reparations to Euler, and as well, the Empress of Russia paid a very substantial sum as compensation. It was well known the Empress of Russia wanted to establish St Petersburg as a learning center for Russians, and Euler would have brought great prestige.

Euler decided to return to St Petersburg, after securing favorable terms for himself and also for his family. In addition, his sons were to be appointed, at the appropriate time, to high positions in the government. In the 1800s the Eulers sons flourished in Russian society.

*Euler Senior*

Until 1738 Euler had good health, then he contracted a serious illness, which caused a high fever, and when it recurred 3 years later, he started losing the sight in the right eye, together with double vision and the eyelid starting to droop.

A decade after that he started having cataract problems in the left eye, and by 1771 Euler was effectively blind. There is a suggestion he had an operation to remove the cataract, and if that is correct, it was not successful.

His response to his blindness was that he would now be less distracted. In the last year of his life, he was averaging an original research paper at the rate of one a week, using a scribe and dictating from memory.

He died suddenly in 1783 at his home, while discussing the planetary motion of Uranus. The possible cause may have been a brain hemorrhage.

Click here to honor one of the greatest.