Leonhard Euler

Leonhard Euler was born in Basel, Switzerland on 15 April 1707. One of 18th century Europe’s brightest minds, the Swiss polymath was active as a mathematician, physicist, astronomer, logician, geographer, and engineer. A prominent figure in the growing universities of St. Petersburg and Berlin, Euler’s contributions furthered the fields of geometry, trigonometry and calculus for decades.

His eyes are light blue. He has diplopia due to his right eye strabismus, which led to progressive atrophy of the right optic nerve and blindness after the left eye cataract surgery. He wears a white draped turban over his greying hair. He is currently wearing a blue and black stripe frock coat.

In 1723, Euler received his Master of Philosophy and enrolled in the theological faculty of the university. He wrote a further dissertation on propagation of sound before applying for a position to teach physics at the university. This was rejected. Instead, he was offered a position at St. Petersburg Academy in Russia, established by Peter the Great in 1724. Alongside his teaching, Euler served as a medical lieutenant in the Russian Navy.

On 1734 he married Katharina Gsell, the daughter of painter Georg Gsell, who would remain his wife for 39 years until her death. They had 13 children, 5 of which survived childhood, and by all accounts were a happy and loving family. Euler claimed to have made some of his best mathematical discoveries while holding a baby or with his children at his feet.

By 1740, Euler was renowned for his work and was personally offered a position at the University of Berlin by Frederick the Great of Prussia. He would spend the next 25 years there in what was his most productive period, writing 380 works (of which 275 were published). His most celebrated is perhaps his "Introductio in analysin infinitorum", which laid the foundations of mathematical analysis and introduced the notation for sin(x) and cos(x).

Frederick asked the mathematician what the best ballistics book was, and Euler chose Benjamin Robin's "New principles of gunnery" published in 1742. Euler also translated it from English into German and added a few comments about it. It was one of the books that most influenced Napoleon's scientists and engineers.

Despite his outstanding academic record, he was passed for the position of President of the Berlin Academy, with Frederick taking the role instead. A simple and devout man, Euler stuck out like a sore thumb at Frederick’s court, who reportedly found Euler unsophisticated and badly informed on matters outside of mathematics.

Euler clashed with the witty Voltaire, who held great standing at court, and the pair were often said to have gotten into lengthy debates at Euler’s expense.

Eventually, Euler was invited to return to St. Petersburg following the country’s stabilisation under Catherine the Great, where he returned in 1766.